WO2011135006A1 - Porte de chalut perforée et procédés - Google Patents

Porte de chalut perforée et procédés Download PDF

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Publication number
WO2011135006A1
WO2011135006A1 PCT/EP2011/056674 EP2011056674W WO2011135006A1 WO 2011135006 A1 WO2011135006 A1 WO 2011135006A1 EP 2011056674 W EP2011056674 W EP 2011056674W WO 2011135006 A1 WO2011135006 A1 WO 2011135006A1
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WO
WIPO (PCT)
Prior art keywords
main deflector
trawl door
deflector body
slat
leading edge
Prior art date
Application number
PCT/EP2011/056674
Other languages
English (en)
Inventor
Sharif Adham Safwat
Valentine Gavrilovich Perevoshchikov
Petur Jensen
Gestur Runarsson
Jon A. Gretarsson
Original Assignee
Hampidjan Hf
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from PCT/EP2010/063499 external-priority patent/WO2011029958A1/fr
Application filed by Hampidjan Hf filed Critical Hampidjan Hf
Publication of WO2011135006A1 publication Critical patent/WO2011135006A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01K—ANIMAL HUSBANDRY; AVICULTURE; APICULTURE; PISCICULTURE; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
    • A01K73/00—Drawn nets
    • A01K73/02—Trawling nets
    • A01K73/04—Devices for spreading or positioning, e.g. control thereof
    • A01K73/045—Devices for spreading or positioning, e.g. control thereof for lateral sheering, e.g. trawl boards

Definitions

  • the present disclosure relates generally to trawl doors used in trawl fishing, seismic surveillance line spreading and spreading of other items towed in water and, more particularly, to trawl doors adapted for more stable, more efficient operation at all angles of attack, including large and small angles of attack, while also being useful at both shallow water trawl fishing applications as well as deep water trawl fishing applications, and while also being useful at bottom trawl fishing applications as well as at pelagic trawl fishing applications.
  • a main problem in the use of trawl doors to spread open the mouth of a trawl net or to spread apart a seismic surveillance array in marine seismology is that trawl doors make up a large quotient of the drag of a trawler or seismic surveillance vessel, which costs fuel usage to overcome. Due to a generally constant trend of increasing fuel costs a demand constantly exists for increasingly efficient trawl doors.
  • Another main problem in the use of trawl doors to spread open the mouth of a trawl net is that, despite various claims, no one single trawl door has been proposed that can operate with maximal efficiency at both very shallow depths, for example depths of less than twenty fathoms, and also at very deep depths, for example depths exceeding 150 fathoms. Furthermore, also despite various claims, no one single trawl door has been proposed that can operated efficiently and reliably in all the rigors of bottom trawling while also being sufficiently efficient to be useful in pelagic trawl fishing operations.
  • a trawl door that exhibits bettered stability.
  • One measure of bettered stability for the purposes of the instant disclosure is a trawl door that exhibits superior lift at a greater range of angles of attack compared to a version of at trawl door exhibiting yet more superior or similar lift at a narrower range of angles of attack, as the variations in cross currents, and constant turning of fishing trawlers constantly alters trawl door angle of attack, as does the variation in trawl net loading and drag from the towed trawl net.
  • Japanese Patent Applications JP 04183343 A and JP 04287632 A, and United States patents US 5,267,408 and US 5,283,972 also propose closeable apertures formed in main wings and or main deflector bodies of trawl door for the purpose of reducing lifting forces and drag when such apertures are open and also for the purpose of increasing lifting forces when such apertures are close.
  • Trawl door efficiency is also improved.
  • perforations are not formed in a main wing including in a main deflector of the trawl door, but rather are formed in a slat that is disposed above and adjacent to the trawl door's main deflector.
  • This teaching has been successful in the industry, but it has the drawback of being rather expensive to produce, and having a substantial increase in weight, limiting its use in some applications. Nonetheless, despite its increased lift and efficiency, a demand continues to exist in the industry for a more efficient trawl door construction that is lower in weight than the trawl door taught in WO 2008/129068 A1 .
  • the present trend in the industry and the state of the art is that when forming trawl doors from bent steel plates, that the plates forming the main deflector and the leading slats have a similar including same thickness. Furthermore, the state of the art and trend in the industry is either to add extra reinforcement to a forward leading edge slat on a trawl door, or that a forward leading edge slat on any trawl door shall be formed from a strongest and thickest bent steel plate on a trawl door, and formed of a thicker plate of steel that is subsequently bent than is formed either a main deflector or another slat, such as a trailing leading edge slat.
  • Historical trawl doors including seismic deflectors that include several foils of same or similar profile and having same or similar distances between the leading and trailing edges of various of the multiple foils able each to be considered as "main deflectors" are not to be confused with trawl doors of the present disclosure.
  • PCT Published Patent Cooperation Treaty
  • WO 2006/01 1 163 A3 International Application Number PCT/IS2003/000025 that is entitled "High Speed, Increased Hydrodynamic Efficiency, Light-Weight Molded Trawl Door and Methods for Use and Manufacture” describes molding portions of a trawl door's body from a synthetic material able to receive impacts fracture free, with a preferred profile being a particular airfoil profile in combination with a variety of leading edge slats, and in some cases also trailing edge slats.
  • PCT Published Patent Cooperation Treaty
  • PCT/EP2008/060045 that is entitled "High Stability, High Efficiency Trawl Door and Methods” describes a trawl door having a particular profile with a particular arrangement of leading edge slats relative to a main deflector body and particular angles of inclination of such leading edge slats, providing for a profile for a trawl door of superior efficiency compared to earlier trawl doors, and useful in certain aspect ratios, and useful in dihedral trawl door constructions.
  • DEFINITIONS ASPECT RATIO means the Trawl Door Height relative to the Trawl Door Width.
  • a trawl door having a trawl door height of two (2) meters and a trawl door width of one (1 ) meter has an Aspect Ratio of 2:1 (two to one).
  • PROFILE means the cross-sectional shape of a trawl door, or of a portion of a trawl door, viewed in a plane that is oriented perpendicularly across the trawl door's vertical dimension.
  • TRAWL DOOR means any of a variety of essentially rigid structures having generally rigid deflectors (e.g. not formed of a foldable fabric as a kite) that is adapted for deployment in a body of water behind a towing vessel. More specifically, trawl door means any generally wing shaped and/or fin shaped device used to spread either a fishing net, such as a trawl, or to spread a seismic surveillance array and/or seismic array, such as used in making acoustic surveillance of a sea floor and sub-sea-floor, or to spread apart any other towed item, whether in air or sea.
  • a trawl door usually attaches at a fore end to a terminal end of a main towing warp or other towing line depending from the towing vessel, and at an aft end to at least one other line itself ultimately attached to another towed item.
  • trawl doors convert a portion of forward motion and/or energy imparted by the towing vessel into horizontally directed force for the purpose of spreading in a generally horizontal direction a trawl, seismic surveillance towed array complex, paravane line or the like.
  • TRAWL DOOR HEIGHT is defined by the shortest distance between the trawl door's upper edge and the trawl door's lower edge and does not include a weight shoe or similar structure but rather relates only to that portion of a trawl door's structure that is intended to efficiently generate lift and/or thrust.
  • TRAWL DOOR WIDTH is defined as the shortest distance between the trawl door leading and trailing edges as taken from a profile of the widest portion of that portion of the trawl door's structure intended to efficiently generate lift and/or thrust. Disclosure
  • the trawl door of the present disclosure is able to provide by combination of slit shaped perforations formed mainly in a region of the trawl door's main deflector body where such region corresponds to the most aft thirty-two percent of the chord length of the main deflector body, especially where the trawl door has one main deflector body and at least one leading edge slat having its leading edge disposed forward of the leading edge of the main deflector body and also where such leading edge slat has its leading edge not situated on an imaginary straight line connecting leading and trailing edges of the main deflector body, and such one main deflector body has a chord length that is greater than a chord length of any other foil forming the trawl door, and especially is at least twenty-two percent greater than the chord length of any other foil forming the trawl door, and more preferably at least twenty- seven percent greater, and the at least one leading edge slat has a trailing edge entirely situated above a tangent plane
  • the trawl door of the present disclosure is formed of a main deflector having a profile that varies, then the main deflector's chord length is expressed as an average of the different chord lengths of the main deflector body, and such is intended to be understood and encompassed by the claims of the present disclosure.
  • the trawl door includes an interior slat situated adjacent to the main deflector body and near its inner side surface, providing a highly efficient and more powerful trawl door.
  • the trawl door of the present disclosure is able to provide by inclusion of the above features with a combination of certain camber relationships of leading edge slats relative to a main deflector body, in certain aspect ratios, with or without certain thickness relationships for plates forming leading edge slats and a main deflector body where such leading edge slats and such main deflector body are formed with a similar curvature to their exterior (i.e. "outer") and interior (i.e.
  • the trawl door of the present disclosure is able to provide by combination of certain camber relationships of leading edge slats relative to a main deflector body, in certain aspect ratios, with certain thickness relationships for plates forming leading edge slats and a main deflector body where such leading edge slats and such main deflector body are formed with a similar curvature to their exterior (i.e. "outer") and interior (i.e.
  • a trawl door is provided with a forward perforated slat constructed similarly to that perforated slat taught in that published PCT application entitled "Perforated Slat Trawl Door” but rather than disposed outboard of, adjacent to and removed from the main deflector being disposed outboard of, removed from and adjacent to a leading edge slat, and preferably a forward leading edge slat.
  • a forward perforated slat constructed similarly to that perforated slat taught in that published PCT application entitled "Perforated Slat Trawl Door” but rather than disposed outboard of, adjacent to and removed from the main deflector being disposed outboard of, removed from and adjacent to a leading edge slat, and preferably a forward leading edge slat.
  • Another advantage of the disclosed trawl door is that it possesses the ability to be efficiently and practically used at both relatively shallow depths as well as at relatively deep depths and at all depths in.
  • Yet another advantage of the disclosed trawl door is that it possesses the ability to be efficiently and practically used at relatively slow tow speeds as well as at relatively fast tow speeds.
  • Yet another advantage of the disclosed trawl door is that it possesses the ability to be efficiently and practically used at a wide range of angles of attack including relatively shallow angles of attack as well as relatively great angles of attack.
  • Yet another advantage of the disclosed trawl door is that it possesses the ability to be efficiently and practically manufactured and deployed, thereby reducing costs to produce and acquire the trawl door.
  • Yet another advantage of the disclosed trawl door is that it possesses the ability to allow a fishing vessel to operate with only one set of trawl doors for all its variety of trawl fishing needs, thereby reducing costs to operate the fishing vessel.
  • FIG. 1 is a plan view of the inner side of a trawl door of the present disclosure, that preferably is a dihedral shaped trawl door;
  • FIG. 1 A is a outer side view of the trawl door of the present disclosure shown in
  • FIG. 1 also known as a back side view, where most structural features of the trawl door not being solely the primary lift generating features of the trawl door are not shown so as not to clutter the drawing, the drawing not necessarily in the same scale as the drawing of FIG. 1 .
  • FIG. 1 B is a detail view of a portion of FIG. 1 A.
  • FIG. 1 C shows an alternative embodiment of the trawl door of the present disclosure shown in FIG. 1 A, the drawing not necessarily in the same scale as the drawing of FIG. 1 .
  • FIG. 1 D shows an alternative embodiment of the trawl door of the present disclosure shown in FIG. 1 A, the drawing not necessarily in the same scale as the drawing of FIG. 1 or of FIG. 1 C.
  • FIG. 2 is front side view of a trawl door of the present disclosure, illustrating the preferred dihedral construction (i.e. Vee shape) of the trawl door of the present disclosure.
  • FIG. 3 is a planar cross sectional diagram taken along the line 3-3 in FIG. 1 illustrating a trawl door profile exemplifying one particular type of trawl door configuration to which the present disclosure is applicable for which the leading slats and the main deflector body have arcuate profiles, with various important distances, important linear axes and important angles of inclination being depicted, with optional perforated slats being associated with the forward leading edge slat and with the main deflector body as empirically determined useful after having read the present disclosure and as disclosed;
  • FIG. 3A is an alternative embodiment of the trawl door profile shown in FIG. 3 where the only difference is that the trawl door lacks a forward perforated slat and lacks a main wing perforated slat.
  • FIG. 4 is a planar cross sectional diagram taken along the line 3-3 in FIG. 1 illustrating another type of trawl door profile exemplifying one particular type of trawl door configuration to which the present disclosure is applicable for which the leading slats and the main deflector body have arcuate profiles having differing thicknesses;
  • FIG. 5 is a planar cross sectional diagram taken along the line 3-3 in FIG. 1 illustrating another type of trawl door profile exemplifying one particular type of trawl door configuration to which the present disclosure is applicable for which the leading slats and the main deflector body have arcuate profiles having differing thicknesses;
  • FIG. 6 is a planar cross sectional diagram taken along the line 3-3 in FIG. 1 illustrating another type of trawl door profile exemplifying one particular type of trawl door configuration to which the present disclosure is applicable for which the leading slats have arcuate profiles and the main deflector body has an airfoil shaped profile;
  • FIG. 7 is a planar cross sectional diagram taken along the line 3-3 in FIG. 1 illustrating another type of trawl door profile exemplifying one particular type of trawl door configuration to which the present disclosure is applicable for which a leading slat and the main deflector body both have an airfoil shaped profile and both have a perforated slat associated with them;
  • FIG. 8 is a planar cross sectional diagram taken along the line 3-3 in FIG. 1 illustrating another type of trawl door profile exemplifying one particular type of trawl door configuration to which the present disclosure is applicable for which a leading slat has an airfoil profile and the main deflector body has an arcuate shaped profile, that is most applicable at trawling angles of attack and some seismic angles of attack;
  • FIG. 9 is a planar cross sectional diagram taken along the line 3-3 in FIG. 1 illustrating another type of trawl door profile exemplifying one particular type of trawl door configuration to which the present disclosure is applicable for which a leading slat has an airfoil profile and the main deflector body has an arcuate shaped profile, that is most applicable at seismic angles of attack and may be useful at very high speed trawling angles of attack;
  • FIG. 10 is a planar cross sectional diagram taken along the line 3-3 in FIG. 1 illustrating another type of trawl door profile exemplifying one particular type of trawl door configuration to which the present disclosure is applicable that is similar to the profile illustrated in FIG. 3, and for which a preferred outline shape of trawl door support plates (not necessarily taken along the line 3-3) is super imposed on the profile;
  • FIG. 1 1 is a front view of a trawl door a trawl door of the present disclosure, illustrating the preferred Vee shaped (i.e. dihedral) construction of the trawl door having the support plates whose outline shape is shown in FIG. 10;
  • FIG. 12 is a schematic diagram of a back strop remotely controllable mechanism of the present disclosure for altering the angle of attack and optionally tilt angle of a trawl door of the present disclosure
  • FIG. 13 is a schematic diagram of a main bracket / main warp attachment assembly remotely controllable mechanism of the present disclosure for altering the angle of attack and optionally the tilt angle of a trawl door of the present disclosure;
  • FIG.14 is a side view of a portion of the mechanism shown in FIG. 13;
  • FIG. 15 is a schematic diagram of a main bracket / main warp attachment assembly remotely controllable mechanism of the present disclosure for altering the angle of attack of a trawl door and optionally also for altering the tilt angle of the trawl door of the present disclosure;
  • FIG. 16 is a schematic diagram viewed from the top side of another remotely controllable mechanism of the present disclosure for altering the attack angle and optionally the tilt angle of a trawl door of the present disclosure;
  • FIG. 17 is a schematic viewed from the front side of another remotely controllable mechanism of the present disclosure for altering the attack angle and optionally the tilt angle of a trawl door of the present disclosure
  • FIG. 18 is a plan view of the back (outer) side of a trawl door of the present disclosure, illustrating another preferred Vee shaped (i.e. dihedral) construction of the trawl door of the present disclosure as used mainly for bottom trawling but also can be used for pelagic trawling, with various important backstrop attachment parameters depicted;
  • FIG. 19 is a front plan view the trawl door of the present disclosure illustrated in
  • FIG. 18 and also illustrating the preferred Vee shaped (i.e. dihedral) construction of the trawl door of the present disclosure as used mainly for bottom trawling but also can be used for pelagic trawling, with various important backstrop attachment parameters depicted;
  • FIG. 20 is a planar cross sectional diagram taken along the line 3-3 in FIG. 1 illustrating another type of trawl door profile exemplifying one particular type of trawl door configuration to which the present disclosure is applicable for which the leading slats and the main deflector body have arcuate profiles and a half-pipe like side slat is associated with the upper and lower edges of the trawl door in place of planar support plates;
  • FIG. 21 is a front plan view of the trawl door having the profile illustrated in FIG. 20, and especially is mainly useful as a bottom trawl door but also can be used for pelagic trawling;
  • FIG. 22 is a top plan schematic view depicting offset arrangements for main deflector bodies forming another alternative trawl door construction of the present disclosure
  • FIG. 23 is a general side plan view of the inner side of another trawl door construction of the present disclosure useful mainly in pelagic trawling but also can be used in bottom trawling, illustrating a preferred rigging configuration of the present disclosure for backstrops of the present disclosure.
  • a preferred trawl door for trawl fishing applications for the purpose of the present disclosure as well as for many other uses of a trawl door of the present disclosure is a Vee shaped, i.e. dihedral trawl door, identified in FIG. 1 and FIG. 2 by the general reference character 10.
  • the trawl door of the present disclosure includes upper and lower trawl door sections 28 and 29, each lying in different planes that diverge and have an included angle 999 measured between the outer side convex surfaces of the upper and lower trawl door sections 28 and 29, where the included angle is lesser than one hundred eighty degrees.
  • the included angle 999 also is measured between the outer side surfaces 56 and 228 (see also FIG. 3) of the upper and lower main deflector bodies 24 and 25 that are included within the upper and lower trawl door sections 28 and 29, respectively, and such included angle is lesser than one hundred eighty degrees.
  • the terms "main wing”, “main deflector body”, “deflector body” and “main deflector” are the same.
  • FIG. 1 to 1 E that are common to the trawl door illustrated in FIG. 1 to FIG. 2 may for clarity carry the same reference numeral distinguished by a prime ( ) designation.
  • FIG. 1 shows the aft portion of a plurality of slits 1 10 forming a perforated region of the main deflector of the trawl door of the present disclosure.
  • the trawl door of the present disclosure includes at least one forward leading edge slat having its leading edge disposed forward of the leading edge of the main deflector body, and as taught further herein, the majority of the perforated area of the main deflector body mainly lies within a portion of the trawl door that corresponds to the most aft twenty-two percent of the chord length of the trawl door, i.e. to that twenty-two percent most proximal the trawl door's trailing edge of a distance measured along an imaginary straight line connecting leading and trailing edges of the trawl door.
  • interior slat 1 1 1 having upper trawl door interior slat portion 1 12 and lower trawl door interior slat portion 1 13 is situated adjacent to and removed from the inner side surface of the main deflector body.
  • FIG. 1 A shows the backside surface of the trawl door of the present disclosure, also referred to herein as the outer side surface of the trawl door of the present disclosure, where most structural features of the trawl door not being solely the primary lift generating features of the trawl door are not shown so as not to clutter the drawing, the drawing not necessarily to scale.
  • slit shaped perforations 1 10 are evidenced.
  • the slits may be rectangular in shape, or have rounded short sides. It has been surprising found that the arrangement and distribution of the slits for a dihedral shaped trawl door is more critical than for a straight, or flat trawl door.
  • a distance from the uppermost perforated slit 1 15, i.e. that perforated slit most proximal the upper edge of the trawl door, to the lowermost perforated slit 1 16, i.e. that perforated slit most proximal the lower edge of the trawl door be a distance that is at least thirty-three percent of the wing span 1 17 of the trawl door, and more preferably at least fifty-three percent of the wingspan 1 17 of the trawl door, yet more preferably at least seventy-three percent of such wingspan and yet more preferably at least eighty-three percent of such wingspan, with at least ninety- four percent of such wingspan being preferred.
  • the distance from the uppermost perforated slit 1 15 to the lowermost perforated slit 1 16 be a distance that is at least fifty-three percent of the wingspan 1 17 of the trawl door, yet more preferably at least sixty-two percent of such wingspan, yet more preferably at least seventy-three percent of such wingspan and yet more preferably at least eighty-three percent of such wingspan, with at least ninety-four percent of such wingspan being preferred.
  • the portion of the main deflector body corresponding to the most aft thirty-two percent of the chord length of the main deflector body (herein also known as "the main deflector perforated zone") have a total perforated area that is at least twelve percent of the main deflector perforated zone, more preferably at least eighteen percent, yet more preferably at least twenty-four percent, yet more preferably at least thirty- four percent, yet again more preferably at least thirty-nine percent, yet again even more preferably at least forty-five percent, up to and including seventy five percent or greater.
  • the perforated area of the main deflector perforated zone preferably is at least twenty-four percent, and can be preferably at least forty percent and even more.
  • dashed line 1 18 is the leading edge 1 18 of the interior slat as hidden from view behind the main deflector body
  • dashed line 1 19 is the trailing edge 1 19 of the interior slat also as hidden from view behind the main deflector body.
  • slit shaped perforations 1 10 have a long dimensions indicated by imaginary axis line 120, and a short dimension indicated by imaginary axis line 121 . While the preferred shape for the perforations 1 10 is slit shape with rounded short sides or a slit shaped rectangle, other elongated shapes are useful, the main requirement being that the shape have a long dimension and a short dimension. Preferably, the long dimension is at least three times greater in length than the short dimension, and more preferably at least four times greater in length, and yet more preferably at least five times greater in length up to and exceeding ten times greater in length than the short dimension.
  • the long dimension of the trawl door is such that long dimension axis line 120 is parallel to an imaginary straight line connecting the shortest distance between the leading and trailing edges of the main deflector body, for example a line connecting the leading and trailing edges of the main deflector body and lying within a plane defined by the profile of the main deflector body, such as a line corresponding in orientation to line 3-3 in FIG. 1 .
  • the long dimension of slit shaped perforations 1 10 may vary, and/or may vary between various of the slit shaped perforations.
  • the majority of the perforations are configured so that the perforations include an angle 127 (see FIG. 1 C) of lesser than eighty-two degrees defined between the majority of each perforation's long dimension axis line 120 and an imaginary straight line connecting the shortest distance between the leading and trailing edges of the main deflector body, where such lines are co-planar.
  • the angle 127 is lesser than thirty-four degrees, yet more preferably lesser than twenty-six degrees, and yet more preferably lesser than twenty-one degrees.
  • the slit shaped perforations in the upper portion of the trawl door may have a different orientation than slit shaped perforations in the lower portion of the trawl door.
  • the exact amount of deviation of the long dimension of each slit shaped perforation may vary within each of the upper and lower portions of the trawl door, as may be experimentally determined after having read the present disclosure. As shown in FIG. 1 C, the exact amount of deviation of the long dimension of each slit shaped perforation may vary within each of the upper and lower portions of the trawl door, as may be experimentally determined after having read the present disclosure. As shown in FIG.
  • the forward portion 122 of the upper trawl door portion slit shaped perforations are more proximal the upper edge of the trawl door than are their aft portion 123
  • the forward portion 122 of the lower trawl door portion slit shaped perforations are more proximal the lower edge of the trawl door than are their aft portion 123.
  • This embodiment of the present disclosure is particularly preferred when used in combination with the support plates of the present disclosure as taught in reference to FIG. 10 and FIG. 1 1 of the present disclosure.
  • FIG. 1 D shows yet another example of where the long dimension of the trawl door is such that axis line 120 is not parallel to an imaginary straight line connecting the shortest distance between the leading edge of the main deflector body to the trailing edge of the main deflector body, where both lines lie in the same plane.
  • the forward portion 122 of each of the majority of the slit shaped perforations is more proximal the upper edge of the trawl door than is the aft portion 123 of each of the slit shaped perforations.
  • strengthening ribs 933, or "bananas" 933 see FIG. 1 and FIG.
  • a perforated slat 54 be employed with a trawl door of the present disclosure as shown in FIG. 3, whether or not the main deflector body is perforated, or should a forward perforated slat 52 be employed with a trawl door of the present disclosure, whether or not the main deflector body is perforated, the slit shaped perforations of such perforated slat 54 and/or such forward perforated slat 52 may also be oriented as taught herein for the slit shaped perforations formed in the main deflector body of the trawl door of the present disclosure.
  • Such teachings for the orientations of slit shaped perforations when used in a trawl door of the present disclosure having support plates of the present disclosure as disclosed in reference to FIG. 10 and FIG. 1 1 also is useful when forming a trawl door of the present disclosure either with perforated slat 54, or with the forward perforated slat 52 and/or when using both the perforated slat 54 and the forward perforated slat with support plates of the present disclosure, even when the trawl door of the present disclosure lacks the perforations in the main deflector body.
  • the walls defining the periphery of the slit shaped perforations 1 10 of the trawl door of the present disclosure preferably are completely enclosed by the main deflector body.
  • FIG. 4 to 20 that are common to the trawl door profile illustrated in FIG. 3 and FIG. 3A, those elements depicted in FIG. 15 and 16 that are common to FIG. 13 and those elements depicted in FIG. 23 that are common to the trawl door illustrated in FIG. 1 to 2, carry the same reference numeral distinguished by a prime ( ) designation.
  • FIG. 3 shows a profile for the trawl door of the present disclosure that is especially efficient at shallow, moderate as well as at high angles of attack and increases the range of use at which the trawl door of the present disclosure can ideally be used.
  • the profile of the trawl door is taken along line 3-3 of FIG. 1 . As shown, the profile includes perforated slit 1 10, and interior slat 1 1 1 .
  • the profile includes a forward leading edge slat 20 having a leading edge 12 and a trailing edge 36, where the leading edge 12 is not situated upon the axis of an imaginary straight line 88 connecting leading and trailing edges 42, 14 of the main deflector body 24, but that rather is situated above such straight line (it is understood in the art that the term "above” as used herein means being situated on a side of such straight line 88 that is a side including the profile of the main deflector and/or including a majority of the profile of the main deflector, rather than on another side of such straight line that is a side not including the profile of the main deflector and/or not including a majority of the profile of the main deflector).
  • the profile includes trailing leading edge slat 22 having leading edge 38 and trailing edge 40, where the leading edge 38 also is not situated upon the axis of line 88, but also preferably is situated above line 88.
  • the forward and trailing leading edge slats 20 and 22 are each formed of a cambered plate, as shown, it is preferable that the leading edges of such forward and trailing leading edge slats are disposed above such line 88, as shown.
  • the portion of the trawl door having the profile is configured so that a line 83 joining leading and trailing edges 12, 14 of the trawl door and a line 88 joining leading and trailing edges 42, 14 of the main deflector body are not coaxial.
  • the portion of the trawl door having the profile is configured so that a line joining leading edge 38 of the trailing leading edge slat and the trailing edge 14 of the main deflector body and the line 88 joining leading and trailing edges 42, 14 of the main deflector body are not coaxial.
  • FIG. 3A shows a profile for a preferred embodiment of the trawl door of the present disclosure that differs only from that embodiment of a preferred profile of a trawl door of the present disclosure taught in FIG. 3 in that the profile taught in FIG. 3A lacks a forward perforated slat 52 and a perforated slat 54.
  • This embodiment may be preferred to minimize weight, as is important for surface fishing, to minimize cost, and in some instances to maximize efficiency.
  • the majority of the perforated area of the main deflector body lies mainly in a zone 124 of the main deflector body that corresponds to the most aft thirty-two percent of the chord length of the main deflector body, i.e. corresponding to that zone commencing at the trailing edge of the main deflector body and including thirty- two percent of a shortest distance measured between the leading and trailing edges of the main deflector body.
  • terminal main deflector body strip 126 is situated aft of main deflector body perforated zone 124.
  • the main deflector body strip 126 preferably has a terminal end defining the terminal end of the main deflector body, where such terminal end is larger in a dimension measured form the outer side surface of the main deflector body to the inner side surface of the main deflector body than is a portion of the plate forming the deflector body as found in a region of the main deflector body that is midway between leading and trailing edges of the main deflector body.
  • the slit shaped perforations preferably have a length that is about thirteen hundredths of the length of the main deflector body's chord length, and can vary from three hundredths to thirty-three hundreds of the main deflector body's chord length while still remaining within that portion of the main deflector body due to the most aft thirty-two percent of the main deflector body's chord length, due to the cambered shape of the main deflector body.
  • the width of the slits that is their short dimension, preferably is from two hundredths to about four hundredths the chord length of the main deflector body, with about five millimeters being a minimal desired width for the slit shaped perforations.
  • a distance between adjacent slit shaped perforations preferably is about the same as the width of the slit shaped perforations, and can be about five millimeters to about twenty-five millimeters, or greater, as empirically determined suitable after having read the present disclosure.
  • the main deflector body strip 126 is preferably about seven hundredths the length of the main deflector body's chord length, and can vary, as empirically determinable after having read the present disclosure.
  • the interior slat's chord length preferably is about twenty five percent of the length of the main deflector body's chord length, and can vary as empirically determinable after having read the present disclosure.
  • the leading edge 1 18 of the interior slat preferably is situated aft of a point located in a zone that is located midway between the leading and trailing edges of the main deflector body. Both the leading and trailing edges of the interior slat preferably lie above an imaginary straight line connecting leading and trailing edges of the main deflector body.
  • a shortest distance from the interior slat's leading edge to the main deflector body's inner side surface preferably is greater than is a shortest distance from the interior slat's trailing edge to the main deflector body's inner side surface.
  • the shortest distance from the interior slat's leading edge to the main deflector body's inner side surface preferably is about eight-three thousands of the chord length of the main deflector body, and the shortest distance from the interior slat's trailing edge to the main deflector body's inner side surface preferably is about thirty-six thousands of the chord length of the main deflector body.
  • these length's may be the same, and may be approximately four percent to six percent of the chord length of the main deflector body.
  • the interior slat preferably is a cambered plate, such as is formed from rolling a sheet of steel or other plate (including sheet) material.
  • the interior slat may be shaped so as to have an airfoil profile.
  • the interior slat's thickness as indicated by line Ti-Ti in FIG. 3, preferably is similar ("similar" to include “same” for the purposes of the present disclosure) to the thickness of that portion of the main deflector body closest to the interior slat and especially in the zone (124) of perforations (1 10). However, it may be of a lesser thickness, in order to minimize drag. In some cases, as experimentally determinable after having read the present disclosure, it may be of a greater thickness, in order to maximize lift.
  • the trawl door of the present disclosure is useful with a perforated slat 54, such as in order to maximize lift, in order to maximize efficiency the trawl door of the present disclosure preferably is constructed so as to lack any slat or other permanent structure situated outboard that portion of the main deflector body having the slit shaped perforations 1 10.
  • a minimum plate thickness of at least four millimeters as indicated by line T-T in FIG. 3 is preferred so as to provide a minimum wall thickness to the walls of the perforation of at least four millimeters, with at least six millimeters being yet more preferred, with at least eight millimeters being yet more preferred, with at least 10 millimeters being even more preferred, with at least twelve millimeters being even yet more preferred.
  • the perforated slat 54 includes a thickness indicated by reference arrow Tp-Tp of at least a portion of its non-perforated portion that is lesser than the thickness T-T of at least a portion of the main deflector body that is most proximal the perforated slat.
  • Tp-Tp is 3 ⁇ 4, i.e. seventy-five percent of thickness T-T.
  • leading edge of the perforated slat 54 is situated aft of a zone corresponding to a point located midway between the leading and trailing edges of the main deflector body and situated on imaginary straight line 88 connecting leading and trailing edges of the main deflector body.
  • a trawl door having an aspect ratio of at least two and a half to one, i.e. 2.5:1 , and preferably of greater than 2.75:1 , and preferably an aspect ratio of 3:1 (three to one), similar to 3:1 and even greater than 3:1 is able to be made so as to be stable at rather high angles of attack while also exhibiting bettered lift and efficiency, when:
  • the trawl door has leading and trailing edges (12, 261 and 14, 230), at least an upper section (28) and at least a lower section (29), the at least an upper section (28) having at least a main deflector body (24) and the at least a lower section (29) having at least a main deflector body (25), the at least an upper section's main deflector body (24) having an outer side convex surface (56, 228) and the at least a lower section's main deflector body (25) having an outer side convex surface (56, 228), each main deflector body (24, 25) having a leading edge (42, 231 ) and a trailing edge (14, 230), the trawl door having:
  • the at least one slat's leading edge is disposed forward of the leading edge of a main deflector body (24, 25);
  • the at least one slat (22, 260) has a curvature
  • the at least one slat (22, 260) has an acute angle made by a convergence of: (ia) a first imaginary straight line (81 , 82) connecting leading and trailing edges (12, 36 and 38, 40) of the at least one slat (22, 260); and
  • a camber for the at least one slat (20, 22) differs from a camber of the main deflector body
  • chord length of the main deflector body is greater than the chord length of the at least one slat;
  • the main deflector body 14 (and preferably a value of greater than 37 degrees for this angle, yet more preferably greater than 40 degrees for this angle, yet even more preferably greater than forty-two degrees for this angle, and yet even more preferably greater than 43 degrees for this angle);
  • camber of the at least one slat is formed from an a arcuate shape having a radius that is lesser than a radius of an arcuate shape forming the main deflector body;
  • leading edge (38) of the another leading edge slat is near to the imaginary straight line (88) joining leading and trailing edges (42, 14) of the main deflector body;
  • the another leading edge slat has a lesser camber than the at least one slat
  • the at least one slat's leading edge (12) also defines the leading edge of the trawl door
  • the entire trailing edge of the another leading edge slat (22) as well as a portion of the another leading edge slat (22) that is between the leading and trailing edges of the another leading edge slat also lies above a tangent plane of the main deflector body where such tangent plane is parallel to imaginary straight line (88) joining leading and trailing edges (42, 14) of the main deflector body;
  • chord length of the another leading edge slat (22) is greater than the chord length of the at least one slat (20);
  • the leading edge of the another leading slat (22) is either on the axis of imaginary straight line (88) joining leading and trailing edges (42, 14) of the main deflector body, or slightly above such line's axis, or slightly below such line's axis; and
  • the majority of the foil forming the forward leading edge slat (20) is situated forward of the leading edge of the main deflector body;
  • the majority of the foil forming the another leading edge slat (22) is situated forward of the leading edge of the main deflector body.
  • Such a trawl door of the present disclosure as described immediately above can be useful with no perforations 1 10, no interior slat, no forward perforated slat 52 and even with no perforated slat 54, though it presently is preferred to use at least a perforated slat 54, with or without main deflector body perforations 1 10, and it presently is preferred to use such profile in such aspect ratios as taught immediately above with the support plates of the present disclosure.
  • cambered plate in reference to the profile of any slat and/or main deflector of a trawl door of the present disclosure indicates that the profile of such slat and/or main deflector has same or similar cambers and/or curvatures for its outer and inner side surfaces.
  • An arcuate shape is an example of such a profile, whether or not the profile is formed of a radius of a circle or any other arched shape or series of arched shapes.
  • a cambered plate for the purposes of the present disclosure ideally is formed by bending a steel plate, that is by bending a sheet of steel.
  • a cambered plate may be formed by bending any other sheet material, or by molding or casting a material into a form so that its final set phase has the same configuration and shape as a sheet material having been bent.
  • the profile of any slat or main deflector of a trawl door of the present disclosure when termed any or all of "bent sheet”; “bent sheet material”, “cambered plate” and/or “bent steel plate” and the like refers to the fact that in profile such slat and/or main deflector is not clearly airfoil in shape, but has a uniform and/or similar width as measured along a shortest distance from an inner side surface to an outer side surface anywhere along a portion of the majority of such slat's and/or main deflector's profile not necessarily including distal leading and trailing edges.
  • the trawl door include at least one leading edge slat and only one main deflector
  • the profile of the trawl door and/or a profile of at least a portion of the trawl door have characteristics including that:
  • chord direction line is an imaginary straight line joining leading and trailing edges of a main deflector and/or joining leading and trailing edges of a leading edge slat. That is to say, that a distance between leading and trailing edges of the main deflector, i.e. "the main deflector's chord direction line”, is greater than a distance between the leading and trailing edges of any leading edge slat, i.e. is greater than any leading edge slat's chord direction line; and
  • leading edge slats has a leading edge that lies above strait line 88.
  • the leading edge of the forward leading slat and also in certain embodiments (such as when the trawl door's aspect ratio exceeds 2:1 ) that the leading edge of a trailing leading slat also lie above the axis of such imaginary line 88 joining leading and trailing edges of the main deflector.
  • the trawl door combine a shape including upper and lower trawl door sections 28 and 29 that lie in different planes (see FIG. 2), i.e. to provide a Vee shape trawl door and/or any other dihedral form of trawl door (there can be multiple trawl door sections lying in different planes, for example, three or four trawl door sections, or more, each, several or all of which lie in different planes, though at present two sections is preferred.
  • the trawl door When the trawl door's aspect ratio is lesser than 2:1 (two to one) and also lesser than 1 .7:1 (one point seven to one), it is preferred that the trawl door include either two leading edge slats and/or at least two leading edge slats where a forward leading edge slat's leading edge lies further above the imaginary straight line joining leading and trailing edges of the main deflector than lies the leading edge of the trailing leading edge slat (including that the leading edge of a trailing leading edge slat may lie either directly on, below, or above such line 88 when the leading edge of the forward leading edge slat lies both above the leading edge of the trailing leading edge slat as well as above such line 88).
  • the entire trailing edges 36 and 40 of the forward and trailing leading edge slats and in certain useful embodiments at least 4%, at least 7%, at least 15% and much more even exceeding 87% of each such leading edge slat's respective chord length project above a tangent plane of the outer side surface of the main deflector where such tangent plane is parallel to straight line 88.
  • the entire trailing edge of either only the forward leading edge slat or of only the trailing leading edge slat and in certain useful embodiments at least 4%, at least 7%, at least 15% and much more even exceeding 87% of each such leading edge slat's respective chord length so projects above such tangent plane of the main deflector.
  • the entire trailing edge of the trailing leading edge slat and in certain useful embodiments at least 4%, at least 7%, at least 15% and much more even exceeding 87% of its chord length projects above such tangent plane of the main deflector, while in other embodiments it is important that the entire trailing edge of the forward leading edge slat, and in certain useful embodiments at least 4%, at least 7%, at least 15% and much more even exceeding 87% of its chord length projects above such tangent plane of the main deflector.
  • the forward leading edge slat preferably includes a portion of itself the lies above such tangent plane.
  • leading edge slats i.e. the forward and trailing leading edge slats shown herein
  • their entire trailing edges, and in certain useful embodiments at least 4%, at least 7%, at least 15% and much more even exceeding 87% of the chord lengths of such leading edge slats preferably project different distances above such tangent plane, or one such leading edge slat's entire trailing edge projects above such tangent plane while another such leading edge slats entire trailing edge does not project above such tangent plane, as experimentally determined suitable for a particular main deflector's profile after having read the present disclosure.
  • One ordinarily skilled in the art having read the instant disclosure shall be enabled to know to make such experimentation in order to obtain technical parameters for various main deflector profiles, such parameters intended to be encompassed within the scope of the present disclosure
  • the entire trailing edge of that leading edge slat whose leading edge is also the leading edge of the trawl door, and preferably as well at least 2% of its chord length preferably projects less far above such tangent plane than does the trailing edge of another leading edge slat, such as of the trailing leading edge slat.
  • the chord length of the trailing leading edge slat is much less than that of the forward leading edge slat, and in particular is at least 33% less, then the entire trailing edge of the forward leading edge slat may project above the trailing edge of the trailing leading edge slat, and preferably also above such tangent plane.
  • the trawl door of the present disclosure having the features shown and described in reference to FIG. 3 has the taught dihedral construction for improved efficiency during actual trawling operations.
  • the angles of inclination of the leading edge slats differ from one another.
  • the angle of inclination of the forward leading edge slat is greater than the angle of inclination of another leading edge slat used with the trawl door of the present disclosure, e.g. the trailing leading edge slat.
  • Leading edge slats of the present disclosure have their leading edges disposed forward of the main deflector's leading edge, and leading edge slats of the present disclosure have a shorter chord direction line than the main deflector's chord direction line, for example the chord direction line of leading edge slats of the present disclosure preferably are from 30% of to 80% of the length of the chord direction line of a main deflector for a trawl door of the present disclosure and especially preferably are more than 12% shorter, and preferably at least 15% shorter, and preferably again at least 22% shorter, and preferably again at least 30% shorter than the length of the chord direction line of the main deflector with certain embodiments showing at least 50% shorter, at least 55% shorter, at least 60% shorter, and at least 65% shorter.
  • the angle of inclination of the forward leading edge slat is defined by angle 287 made by the convergence and/or divergence of that imaginary straight line joining leading and trailing edges of the main deflector with another imaginary straight line 81 joining leading and trailing edges of the forward leading edge slat.
  • the angle of inclination of the another and especially of the trailing leading edge slat is defined by angle 288 made by the convergence and/or divergence of that imaginary straight line joining leading and trailing edges of the main deflector with another imaginary straight line 82 joining leading and trailing edges of the trailing leading edge slat.
  • the angle of inclination for any leading edge slat of any the trawl door of the present disclosure is an angle formed by the convergence and/or divergence of that imaginary straight line joining leading and trailing edges of the main deflector with another imaginary straight line joining leading and trailing edges of any leading edge slat used in forming the trawl door of the present disclosure.
  • the angles of inclination differ for each of the at least two leading edge slats.
  • the angles of inclination may be similar (the term "similar" as used herein including same).
  • a forward perforated slat 52 preferably is situated adjacent to and removed from the outer side surface 57 of the forward leading edge slat, and possibly is similarly situated above the another leading edge slat and/or slats.
  • the forward perforated slat is constructed of extremely hard steel, in order to minimize abrasion during catastrophic events.
  • a preferred fabrication method includes first forming the perforations in the sheet and/or plate of steel and subsequently rolling it into a desired shape.
  • the cutting by torch or water jet of the sheet material including plate of steel or other metal so as to form the perforations is made prior to rolling the sheet material including plate of steel or other metal into a desired shape, including into a desired camber.
  • a plate of steel preferably first has the perforations formed into it, then it is rolled into a desired camber, and then it subsequently is cut into strips, each of which form a portion of the forward perforated slat or perforated slat, such as an upper and a lower portion and forward and aft portions. Forward perforated slat portions and perforated slat portions for several trawl doors thus may be formed at one time.
  • a sheet of material including a plate of steel preferably first has the perforations formed into it, then subsequently the sheet of material including a plate of steel is rolled into a desired camber.
  • the material When forming either the forward perforated slat 52, the perforated slat 54 or the perforated main deflector body from a cast material, preferably first the material is permitted to set, then the perforations are formed. Finally, undesirable material preferably is removed prior to using the perforated object to form a foil of the trawl door.
  • "Undesirable material” includes material that is protruding either from the inner walls of the perforations and reducing the absolute opening of the perforations, or material that is protruding from the surface of the object whether such object be a sheet material or a cast material, and is so protruding as a result of the forming of the perforations.
  • a raised bead weld and/or a raised round bar of steel is welded to its shorter and/or lateral sides, or a raised fin with a round bar of steel on its outside edge is useful. That is, preferably not on its leading or trailing edges, though possibly but not ideally on such leading and trailing edges, so as to provide a wear buffering rail of steel formed to function as sleds should the trawl door fall over and be dragged on its back side, and in such a fashion that does not impeded water flow over, along and about the body of the forward perforated slat (i.e. the wear buffering rail is lacking from the leading and trailing edges of the forward perforated slat).
  • the perforated slat itself may also have such wear buffering fins and/or rails in corresponding locations.
  • the forward perforated slat as well as the perforated slat are affixed at their lateral sides to the trawl doors upper and lower end plates.
  • several raised fins extend from the outer side surface of the portion of the trawl door above which is situated either or both the forward perforated slat and the perforated slat, and the forward perforated slat as well as the perforated slat are welded to such raised fins on their undersides, and in some cases are formed as several liner sections and then welded to such raised finds on both their undersides as well as the lateral sides of such sections.
  • the sectioning of the forward perforated slat and of the perforated slat permits easy replacement of a damaged portion, and also prevents any particular impact event from destroying the majority of, for example, the forward perforated slat.
  • the aspect ratio of the trawl door exceeds 2:1 (two to one) the angles of inclination differ for each of the at least two leading edge slats, and the angle of inclination of the forward leading edge slat (i.e that leading edge slat whose leading edge also forms the leading edge of the trawl door) is greater than an angle of inclination of another leading edge slat, i.e. is greater than the angle of inclination of the trailing leading edge slat.
  • This feature can also be useful when the aspect ratio is from 0.5:1 to 3.9:1 , as experimentally determined useful after having read the present disclosure.
  • the aspect ratio is lesser than 2:1
  • the angles of inclination may be similar (including the same) or within three to four degrees of one another for each of the at least two leading edge slats.
  • This feature is especially useful when the aspect ratio is less than 2:1 (two to one), less than 1 .5:1 (one point five to one), less than 1 .25:1 (one point twenty-five to one); less than 1 :1 (one to one), less than 0.75:1 (zero point seventy-five to one ); less than 0.6:1 (zero point six to one) and lesser.
  • it is important that at least a portion of at least one of the leading edge slats has a profile that:
  • a) is formed either from an arc of a circle (or from some other bent sheet shape, such as from an arcuate shape)having a radius that is half (50%) or about half of the radius forming an arc of a circle forming at least a portion of the profile of the main deflector body and/or another leading edge slat and especially a trailing leading edge slat; or
  • a profile having a greater camber shall include that if a profile of a leading edge slat and/or a main deflector is not formed of an arc of a circle, but rather is formed of a series of connected flat sides, or of any other non-circular concave shape, including a non-airfoil shaped profile concave shape such as slat having a profile formed from a portion of a quasi- circular shape.
  • a profile's "concavity” shall mean: a distance exhibited along a length of a first straight line intersecting a chord direction line of a certain concave profile at a midpoint between such concave profile's leading and trailing edges, where such first line is normal to the chord direction line of the concave profile and the length of such first line is measured from the point of such first line's intersection with the chord direction line to such intersecting lines contact with the inner side (concave) surface of the concave profile; or, should such concave profile be perforated, where such intersecting line reaches a point in space along another imaginary straight line joining the shortest distance between nearest solid portions of such concave profile.
  • the greater is a ratio obtained by dividing the length of such first line by the length of that chord direction line intersected by such first line, the greater is the concavity of a certain slat and/or main deflector's profile.
  • the forward leading edge slat has a profile that is formed from an arc of a circle and/or mainly formed from an arc of a circle where such arc of a circle has a radius that is half (50%) of a radius forming an arc of a circle forming the profile of the main deflector, and/or mainly forming the profile of the main deflector, or is from 45% to 65%, or from 40% to 70%, and at least 33%.
  • a forward leading edge slat may be formed of an arc of a circle having a radius that is about 20% to 25%, or from 20% to 33% that of the arc of a circle from which is formed a main deflectors profile.
  • such forward leading edge slat is located rather high above line 88, so that its entire trailing edge, and in certain useful embodiments at least 4%, at least 7%, at least 15% and much more even exceeding 87% of its chord length is able to project above a tangent plane of the outer side surface of the main deflector where such tangent plane is parallel to the main deflector's chord direction line.
  • such forward leading edge slat's entire trailing edge may not project so high above line 88, but at least shall be at a same level above such line 88 as is the trailing edge of a trailing leading edge slat, and may preferably project above such trailing edge of such trailing leading edge slat.
  • a trailing leading edge slat exists having a profile formed from an arc of a circle having a radius that is similar (including same) as that radius forming the arc of a circle from which is formed the main deflector's profile.
  • any aspect ratio trawl door of the present disclosure has two leading edge slats, where a forward leading edge slat has a profile that is formed from an arc of a circle having a radius that is half (50%) of a radius forming an arc of a circle forming the profile of the main deflector. In other embodiments, this percentage may be from 45% to 65%, or even from 40% to 60% from 15% to 90%, from 20% to 80%, from 25% to 75%, or from 30% to 75%).
  • the angle of inclination of the forward leading edge slat preferably is at least 30 degrees, also preferably at least 31 degrees, more preferably at least 32 degrees, and ideally at least 33 degrees, at least 34 degrees and can be from 28 degrees to 34 degrees, and in certain embodiments greater. Also ideally, the angle of another leading edge slat, i.e.
  • the trailing leading edge slat especially when there are only two leading edge slats is at least 28 degrees, more preferably at least 29 degrees, and ideally 30 degrees, and can be from 27 degrees to 31 degrees, and from 26 degrees to 34 degrees and also greater. These angles are especially useful in combination with all the other characteristics described above and below in relation to the portions and features of the profile shown in FIG. 3 for a trawl door of the present disclosure as described herein.
  • the forward leading edge slat's profile with a greater concavity, such as from an arc of a circle having a lesser radius than an arc of a circle forming either or both a main deflector's profile or another leading edge slat's profile (such as a trailing leading edge slat's profile) in the ratios and fashion as taught herein when either or both:
  • the aspect ratio of the trawl door of the present disclosure exceeds 2:1 (two to one); and especially when it exceeds 2.2:1 (two point two to one); exceeds 2.3:1 (two point three to one); 2.4:1 (two point four to one); 2.5:1 (two point five to one); 2.6:1 (two point six to one); and 2.7:1 (two point seven to one); and b) the angle of inclination of at least one leading edge slat, and especially of at least the forward leading edge slat is lesser than 45 degrees, especially lesser than 40 degrees, and especially lesser than 37 degrees, lesser than 36 degrees, lesser than 35 degrees and lesser than 34 degrees, or
  • the aspect ratio is lesser than 2:1 (two to one), lesser than 1 .8:1 (one point eight to one), lesser than 1 .7:1 , lesser than 1 .5:1 , lesser than 1 .3:1 , lesser than 1 .2:1 , lesser than 1 .1 :1 , lesser than 1 :1 , lesser than 0.8:1 , lesser than 0.7:1 and lesser than 0.6:1 ; and
  • the angle of inclination of at least one leading edge slat, and especially of at least a forward leading edge slat is lesser than 36 degrees, lesser than 34 degrees, lesser than 32 degrees, lesser than 31 degrees, lesser than 30 degrees, lesser than 29 degrees, lesser than 28 degrees, lesser than 27 degrees, lesser than 26 degrees, lesser than 25 degrees and lesser than twenty-four degrees.
  • a forward perforated slat 52 is situated above and removed from the outer surface of at least one of the leading edge slats, and possible any and all of the leading edge slats, the trawl door of the present disclosure able to have several leading edge slats.
  • a forward perforated slat 52 is situated above and removed from the outer surface of the forward leading edge slat when there are two leading edge slats, as shown in FIG. 3.
  • the total area of perforations in the forward perforated slat, as well as in the perforated slat 54, is at least 12% of the area of the perforated slat and/or the forward perforated slat, more preferably at least 18% and yet more preferably at least 20% of such area.
  • That position includes that the forward perforated slat's leading edge is situated closer to the trailing edge of the leading edge slat above which the forward perforated slat is situated (in this case that leading edge slat being the forward leading edge slat).
  • a trawl door of the present disclosure having both a forward perforated slat disposed removed from and adjacent to the outer side surface of at least one of the trawl door's leading edge slats and preferably disposed adjacent to and above a forward leading edge slat's outer side surface as shown in FIG. 3 and FIG. 7 also includes the perforated slat 54 disposed adjacent to and removed from the outer side surface of the main deflector and having its trailing edge more proximal the trailing edge of the main deflector than its leading edge is proximal the main deflector's leading edge also as shown in FIG. 3 and FIG. 7, as well as other features of the present disclosure as described herein and especially in reference to FIG.
  • the leading edge slat above which is disposed the forward leading edge slat have a profile including in at least a portion of the profile an arc of a circle and/or a portion of a bent plate, and especially a profile formed of an arc of a circle or mainly formed of an arc of a circle, where the portion of the leading edge slat's profile formed of an arc of a circle has a radius that is both lesser than the radius of an arc of a circle forming and/or mainly forming the main deflector's profile, as well as lesser than a radius of an arc of a circle forming and/or mainly forming another leading slat's profile especially when such another leading edge slat is a trailing leading edge slat.
  • such a trawl door of the present disclosure has a relatively low aspect ratio, such as lesser than 1 .5:1 , lesser than 1 .1 , lesser than 0.75:1 and lesser than 0.6:1 , it is preferably that there be two or at least two leading edge slats, having similar (including same) angles of inclination, where such angles of inclination are approximately twenty-three degrees and from twenty degrees to twenty-five degrees. Should one leading edge slat have a greater angle of inclination, such preferably is the forward leading edge slat, as taught herein.
  • the forward perforated slat's leading edge is positioned such that it is nearer to the forward leading edge slat's trailing edge than to its leading edge, while the trailing edge of the forward perforated slat can be at a location directly above the forward leading edge slat's trailing edge, or further aft of or slightly forward of such forward leading edge slat's trailing edge, as is experimentally determined suitable for any particular trawl door of the present disclosure after having read the present disclosure.
  • the thickness of the profile of the main deflector is greater than the thickness of the profile of the leading edge slats, and especially of the forward leading edge slat.
  • both leading edge slats as well as the main deflector have their profiles formed of arcs of circles (and/or formed of a bent line such as a bent steel plate), that radius of an arc of a circle forming the forward leading edge slat is 50% that or about 50% that of a radius of the arc of a circle forming the main deflector (in other word, the camber of the forward leading edge slat is greater than the camber of the main deflector, and in this case also is greater than the camber of the trailing leading edge slat, a greater camber formed by a lesser radius when the shape is an arc of a circle), the trawl door has an aspect ratio of about 0.56:1 or 0.6:1 , the forward perforated slat is used as shown.
  • the forward perforated slat is used without the perforated slat.
  • the forward perforated slat is used in conjunction with the perforated slat as shown.
  • the thickness of the profile of the main deflector is from 1 .25 times to 25 times the thickness of the forward leading edge slat's profile, and ideally from 2 times to ten times, and more ideally about 4 times (including 4 times) the thickness of the forward leading edge slat's profile.
  • the trailing leading edge slat may also have a thicker profile than the forward leading edge slat in such ratios.
  • the forward leading edge slat may have a thicker profile than a trailing leading edge slat, as can be experimentally determined after having read the present disclosure.
  • the thickness of a profile of any slat and/or main deflector of a trawl door of the present disclosure is measured along a shortest distance between the inner side surface and the outer side surface at any region along the majority of the profile of any slat and/or main deflector of the present disclosure not necessarily including terminal leading and trailing edge, and is for example of a thickness of a main deflector indicated by the shortest distance between arrow head points W-W in FIG. 4 and FIG. 5 and is shown on only the main deflector of FIG. 4 and FIG. 5 for illustrative purposes so as not to clutter the drawings of the present disclosure.
  • Such teachings are contrary to the present state of the art and contrary to the trend in the industry.
  • the thickness of the profile of the main deflector is from 1 .5 times to ten times the thickness of the forward leading edge slat's profile, and can be from 1 .5 times to twelve times or from 1 .5 times to 25 times the thickness of the forward leading edge slat's profile and ideally about 4 times (including 4 times) the thickness of the forward leading edge slat's profile.
  • the trailing leading edge slat may also have a thicker profile than the forward leading edge slat in such ratios, and in certain embodiments the forward leading edge slat may have a thicker profile than a trailing leading edge slat, as can be experimentally determined after having read the present disclosure. This is especially important when the main deflector and a leading edge slat have a profile that is formed of, or that mainly is formed of an arc of a circle and/or bent line (such as from a bent steel plate.
  • the trawl door has:
  • a dihedral shape at least two leading edge slats;
  • a main deflector having profile having a longer chord direction line than a chord direction line of a profile of either of the leading edge slats';
  • the forward leading edge slat having a profile formed of an arc of a circle having a radius smaller than, and specifically about 50% of a radius forming an arc of a circle forming a profile of the main deflector and also of the another leading edge slat;
  • a profile of a portion of the trawl door including a ratio of the main deflector's profiles thickness relative to the another leading edge slat's profile thickness and relative to the forward leading edge slat's profile thickness of:
  • the thickness of the profile of the main deflector can be from 1 .4 times thicker to 30% lesser than the thickness of the profile of a forward leading edge slat, and from 1 .75 times thicker to 20% lesser than the thickness of the profile of a trailing leading edge slat (i.e. another leading edge slat).
  • the ratio of the thickness of the profile of the main deflector relative to the profile of either the forward or trailing leading edge slats can be quite different, as taught herein.
  • the thickness of the profile of the main deflector is from 1 .25 times to 25 times the thickness of the forward leading edge slat's profile, and ideally from 2 times to ten times, and more ideally about 4 times (including 4 times) the thickness of the forward leading edge slat's profile.
  • the trailing leading edge slat may also have a thicker profile than the forward leading edge slat in such ratios, and in certain embodiments the forward leading edge slat may have a thicker profile than a trailing leading edge slat, as can be experimentally determined after having read the present disclosure.
  • any of the foils of the trawl door of the present disclosure when formed of the varying thickness embodiment for the profiles of these foils of the trawl door, most preferably have a uniform thickness throughout most of the length of foil's profile (i.e. the majority of the profile has a uniform thickness, or a thickness that generally is uniform, and especially that for the majority of the profile is within 7% of being the same, and within 6%, within 5%, within 4%, within 3%, within 2% and within 1 % of being the same (see FIG. 4 and FIG. 5).
  • any perforated slat of the present disclosure may also be formed in similar fashion as that shown and otherwise taught herein for the foils of the leading edge slats and main deflector of trawl doors of the present disclosure.
  • Such thicker profiles for foils of trawl doors of the present disclosure may be formed by firstly forming a foil such as a main deflector from a bent steel plate, and secondly attaching to such bent steel plate a similarly shaped body of for example a synthetic substance, so as to arrive at the desired profile.
  • a foil such as a main deflector from a bent steel plate
  • a similarly shaped body of for example a synthetic substance
  • a foil for a trawl door of the present disclosure may be formed of a bent steel plate that has a smooth outer side surface, that has several bananas and/or ribs on its inner side surface, and that has several portions designed, configured and adapted to be inserted in between such bananas and/or ribs and affixed to the bent steel plate's inner side surface by gluing, bolting, clamping on the like.
  • the primary lift generating portion of the trawl door has the desired profile.
  • Nyrim® is considered a suitable synthetic substance for forming such portions of the trawl door. To repair such trawl door, individual damaged portions of the synthetic substance may be removed and replaced.
  • the profiles of trawl door foils of the present disclosure may be formed of double walled steel plates, preferably filled with a closed cell foam.
  • a distance from the leading edge of the trawl door to the leading edge of the main deflector be from 28% to 44% the distance from the leading edge of the trawl door to the trailing edge of the main deflector.
  • this distance is from 30% to 40%, more preferably from 33% to 38%, and yet more preferably from 33.5% to 37.5%.
  • a trawl door of the present disclosure for shallow angles of attack, e.g. 3 degrees to 25 degrees, and especially 5 degrees to twenty degrees, and more especially 5 degrees to 15 degrees, such as useful in surface fishing with synthetic warps and or in seismic applications.
  • Shown is a main deflector formed of an airfoil profile as well as a single leading edge slat, in this case a forward leading edge slat, also formed of an airfoil profile.
  • the trawl door's profile consists essentially of the shown forward leading edge slat as well as of the shown main deflector.
  • a forward perforated slat be positioned removed from and adjacent to the outer side surface of the forward perforated slat, either as shown, or with approximately half the length of the forward perforated slat located above the outer side surface of the forward leading edge slat and with approximately half the length of the forward perforated slat protruding beyond the trailing edge of the forward leading edge slat, the leading edge of the forward perforated slat in such embodiment of the present disclosure located aft of the leading edge of the forward leading edge slat, and approximately midpoint between the leading and trailing edges of the forward leading edge slat.
  • the camber of the forward perforated slat in such embodiment may correspond, or be similar to the camber of the outer side surface of the forward leading edge slat. Or it may be formed from an arc of a circle having a diameter same as or similar to the distance from the leading edge of the trawl door to the trailing edge of the trawl door, or within from at least 50%, to at least 60% to from 66% to 95% of such distance.
  • Both the forward leading edge slat as well as the main deflector have the same profile. It presently is preferred to use that profile having its profile known by the name and/or code "NACA-3381 17" as found in a software programme known as “VisualFoil Version 4.1 ", such software program sold by Hanley Innovations/Dr. P. Hanley, Ocala, FL)".
  • the maximally efficient low-speed high-lift airfoil profile software program is hereby incorporated by reference.
  • a thickest segment that is between thirteen percent (13%) and twenty-four percent (24%) of a chord of the profile; and preferably between 16% and 21 %, and preferably between 17% and 19%, an yet more preferably between 17% and 18%, and;
  • a trawl door of the present disclosure to tow upon and/or influence the position of any portion of a towed seismic array, such as a streamer, super-wide (paravane line), or the like, and the production of data useful in determining the location of solid, liquid and/or gaseous energy reserves, and the method of using such trawl door of the present disclosure is a highly useful embodiment of the instant present disclosure.
  • the trawl door's profile consists essentially of a forward leading edge slat and a main deflector having the "NACA-3381 17" profile mentioned herein as well as varying embodiments of other airfoil profiles as taught herein; including where the profile of the forward leading edge slat as well as the profile of the main deflector both are formed of the same profile such as when both are formed of such "NACA-3381 17" profile.
  • a forward perforated slat in the position as shown adjacent to and removed from the outer side surface of the forward leading edge slat and constructed and configured as taught herein is highly useful for maximizing efficiency of trawl doors of the present disclosure formed as taught in reference to FIG. 7.
  • a perforated slat 54 in the position as shown adjacent to and removed from the outer side surface of the main deflector and constructed and configured as taught herein is highly useful for maximizing stability and thus allowing utilization of maximal efficiency of such embodiment of a trawl door of the present disclosure.
  • a trailing leading edge slat may be used with such profile for such trawl door of the present disclosure as shown in FIG. 7, where such trailing leading edge slat may be formed either of the same airfoil profile as forms the forward leading edge slat, but in a smaller scale. Or, such trailing leading edge slat may be formed of a bent plate, including of an arc of a circle, and may have its trailing edge positioned between the trailing edge of the forward leading edge slat and the line 88, especially for seismic applications and low angle of attack / high speed trawling applications.
  • such trailing leading edge slat may have its entire trailing edge and in certain useful embodiments at least 4%, at least 7%, at least 15% and much more even exceeding 87% of it chord length projecting above a tangent plane of the outer side surface of the main deflector body where such tangent plane is parallel to the chord direction line of the main deflector body.
  • Such embodiment of a trawl door of the present disclosure also usefully has trailing slats 47a located near the trailing edge of the main deflector and removed some distance from the inner side surface (concave side surface) of the main deflector, as shown, that may be straight lines, as shown, or may have a camber similar to the camber of the inner side surface of the main deflector nearest to such slats.
  • the leading edge slat has a forward perforated slat situated relative to the forward leading edge slat's outer side surface as shown in the drawing of FIG. 7 and as taught herein.
  • a leading edge slat and especially where the forward leading edge slat, and also where a main deflector is formed from with a profile that is an airfoil profile, especially the "NACA-3381 17" profile it is preferred that a distance from the leading edge of the trawl door to the leading edge of the main deflector be from 21 % to 34% the distance from the leading edge of the trawl door to the trailing edge of the main deflector.
  • this distance is from 22% to 33%, more preferably from 24% to 30%, yet more preferably from 25% to 29%, and yet more preferably from 26% to 28%, with about 26% and about 27% being highly useful, depending upon exactly what is considered to be the leading edge of the trawl door.
  • leading edge of the forward leading edge slat be situated a height above an axis of the imaginary line connecting leading and trailing edges of the main deflector, especially a height that is from 6% to 27% of the length from the leading edge to the trailing edge of the main deflector, and especially from 8% to 20%, and especially from 10% to 18%, and especially from 12% to 16%, with from 13% to 14% being preferred, and with about 12%, about 13%, and about 14% being highly useful, and at least 5% being useful.
  • the entire trailing edge of the forward leading edge slat and in certain useful embodiments at least 4%, at least 7%, at least 15% and much more even exceeding 87% of it chord length preferably projects above a tangent plane of the outer side surface of the main deflector where such tangent plane is parallel to the chord direction line of the main deflector.
  • such trailing edge of such forward leading edge slat is situated a distance above the outer side surface of the main deflector a distance that is at least 4% the length of the chord direction line of the main deflector, more preferably at least 8%, more preferably at least 10%, with about 13.4% being preferred, with from 1 1 % to 21 % being useful, and from 1 1 % to 46% being applicable as experimentally determined useful after having read the present disclosure.
  • the angle of inclination of the forward leading edge slat is usefully from 23 degrees to 34 degrees, with about 28 degrees (including 28 degrees) being presently preferred, with from 26 degrees to 31 degrees being useful, with from 26 degrees to 30 degrees being more useful.
  • a trawl door is formed that is highly useful at a wide range of angles of attack, including at ranges including from 5 degrees to 50 degrees, and from 25 degrees to 45 degrees, by forming the main deflector body with a profile that is an arc of a circle, or that otherwise is formed of a bent plate (including a bent line), including having a substantial thickness as described supra, while simultaneously forming a forward leading edge slat of an airfoil profile, where the maximal thickness of the forward leading edge slat's profile exceeds the maximal thickness of the main deflector's profile.
  • the chord direction line has a lesser length for the forward leading slat than for the main deflector body, however, in certain embodiments this may be reversed.
  • the main deflector body is formed of an arc of a circle as shown for the main deflector bodies of those embodiments of the disclosed trawl door taught in reference to FIG. 4 and FIG. 5, and the forward leading edge slat is formed with an airfoil profile as shown in FIG. 7 and as otherwise taught herein.
  • FIG. 7 shows an embodiment most useful for angles of attack greater than twenty degrees
  • FIG. 9 shows an embodiment most useful for angles of attack lesser than twenty degrees.
  • both the profiles shown in FIG. 8 and in FIG. 9 are useful at a wide range of angles of attack, i.e. both are useful at lesser than or greater than twenty degrees angles of attack.
  • the trawl door is formed as taught herein in reference to FIG. 7 and as otherwise taught herein.
  • reference numerals 464 and 484 indicate various embodiments of a internal main deflector slat.
  • the leading edge of the internal main deflector slat is outside the chord direction line of the main deflector body, and in another it is inside the chord direction line of the main deflector body.
  • a distance between the inside concave surface of the main deflector body and the outer convex surface of the internal main deflector slat is greater in a region proximal the internal deflector body slat's leading edge than it is in a region more proximal the internal deflector body slat's trailing edge.
  • the end plates of the trawl door are preferably formed with a greater amount of surface area than is presently the state of the art and the trend in the industry, especially for angles of attack of lesser than 37 degrees.
  • the term "end plate” shall mean the same as the term "support plate” for the following teachings:
  • FIG. 10 is a bottom plan view of a winglet used in forming the present disclosures trawl door. As shown in FIG. 10, in the presently preferred embodiment the winglet is formed by the support plate of a trawl door of the present disclosure. FIG. 10 shows the profile of primary lift generating portions of the trawl door where such profile attaches to such support plate,
  • FIG. 1 1 is a front plan view of a trawl door of the present disclosure using such support plates of FIG. 10:
  • At least one of the foils is a forward leading slat
  • the most forward leading slat has a portion of a support plate extending both above of as well as below, and with the support plate extending a greater distance below the forward leading slat's chord direction line than it extends below the main deflector's chord direction line, i.e. on both sides of, its convex side surface, where such support plate preferably is connected to the support plate forming a support plate also extending on both sides of a plane contacting the convex side surface of other foils of the trawl doors, especially of:
  • each such support plate having a surface area that is about 0.173 times the surface area of the foils forming the primary lift generating structure of the trawl door. This ratio can be from 0.1 to 0.26.
  • the support plate has a tapered forward edge.
  • the portion of the support plate forward of the leading edge of the main deflector body has a lesser area than the portion of the support plate aft of the leading edge of the main deflector body, preferably at least 90 percent lesser, at least 80 percent lesser, at least 70 percent lesser, and can be at least 60 percent lesser.
  • a ratio obtained by dividing the support plate area above the forward leading slat and/or forward leading slats by the support plate area below the forward leading slat and/or forward leading slats is lesser than another ratio obtained by dividing the support plate area above the main deflector body by the support plate area below the main deflector body.
  • the support plates have a tilt angle, indicated by reference numeral 444, defined as the angle between :
  • (i) lesser than 90 degrees is from 61 degrees to eighty-eight degrees, preferably is lesser than 80 degrees and yet more preferably lesser than 70 degrees, and preferably is from 64 degrees to 71 degrees with about 69 (sixty nine) degrees being most preferred.
  • These teachings are especially useful for all angles of attack including angles for use with trawl doors constructed to be fished with angles of attack greater than 19 degrees and even greater than 45 degrees; and
  • (ii) in certain embodiments can be greater than 90 degrees when for use with trawl doors constructed to be fished with angles of attack lesser than twenty degrees.
  • the upper support plate has a thickness that is lesser than the lower support plate's thickness. They may be made entirely or partially of plastic or synthetic material where the trawl door is made of steel, or include synthetic portions, such as formed of Nyrim, and thus include a material dissimilar to a material from which the majority of the trawl doors mainly is formed.
  • the forward leading edge slat's leading edge is disposed forward of the leading edge of a main deflector body (24, 25);
  • the forward leading edge slat (22, 260) has a curvature
  • the forward leading edge slat (22, 260) has an acute angle made by a convergence of: (ia) a first imaginary straight line (81 , 82) connecting leading and trailing edges (12, 36 and 38, 40) of the forward leading edge slat (22, 260); and
  • a camber for the forward leading edge slat (20, 22) differs from a camber of the main deflector body
  • chord length of the main deflector body is greater than the chord length of the forward leading edge slat;
  • the leading edge of the forward leading slat (22) does not lie on the axis of imaginary straight line (88) joining leading and trailing edges (42, 14) of the main deflector body; 5) the chord length of the main deflector body is at least forty-one percent greater than the chord length of the forward leading edge slat;
  • winglets (preferably formed by the support plates) have a total surface area that is at least twenty percent of the total surface area of the combination of the forward leading edge slat and the main deflector body.
  • the forward leading edge slat's acute angle is greater than thirty-one degrees; Furthermore: when a trailing leading edge slat is used in forming the profile of the trawl door mentioned immediately above, the majority of a foil forming the trailing leading edge slat (22) is situated forward of the leading edge of the main deflector body; and Furthermore again, a plane within which lies the winglet is not parallel to a plane within which lies at least forty percent of the trawl door; and
  • the winglet preferably formed by a support plate, has a tapered forward edge.
  • the winglet preferably formed by a support plate, has a tilt angle 444 that is measured between:
  • winglet plane axis i.e. support plate plane axis
  • tilt angle is an angle being selected from a group consisting of: a) lesser than 90 degrees; b) from 61 degrees to eighty-eight degrees; c) lesser than 80 degrees; d) lesser than 70 degrees; and e) is from 64 degrees to 71 degrees.
  • the forward leading edge slat and the main deflector are hollow and/or include hollow cavities adapted to receive machinery permitting remotely controlling the angle of attack, tilt and yaw of the trawl door.
  • the trawl door of the present disclosure include profiles formed of arcs of circles, where the thickness of the profile permits such hollow cavities, such are preferred.
  • it is useful to form such hollow cavities by constructing a hollow structure to strengthen the leading edge of a foil of the trawl door, such as the leading edge of the main deflector's foil.
  • foil leading edge re-enforcement structure 781 having hollow linear cavity 782 located vertically along the vertical dimension of the leading edge of the foil.
  • the cavity is formed by round bar 783, plate 784, main deflector 24 , and bead welds 785 filling in needed gaps between the round bar, plate and main deflector.
  • the walls of the hollow cavity may be perforated as needed to pass lines including hydraulic lines and other structures.
  • the trawl door is provided with attack angle altering apparatus 790 including a moveable connection point 786 for connecting to main towing warp 74 where such moveable connection point is attached both to an attack angle retractable arm 787 (the term “retractable” as used herein shall include “extendable” and vice versa), such as a hydraulic ram, screw jack, worm gear, chain or cable drive or the like and also is attached to an attack angle length of line 788, that may be a length of chain or even a rigid steel rod or rigid steel plate having a moveable (especially pivotal) attachment point to the trawl door at its end distal from the moveable connection point.
  • attack angle altering apparatus 790 including a moveable connection point 786 for connecting to main towing warp 74 where such moveable connection point is attached both to an attack angle retractable arm 787 (the term “retractable” as used herein shall include “extendable” and vice versa), such as a hydraulic ram, screw jack, worm gear, chain or cable drive
  • the attack angle retractable arm has its long dimension lying and/or mainly lying in a plane that is coplanar with a profile of a portion of the primary lift generating portion of the trawl door.
  • the attack angle retractable arm is more forward of the both the moveable connection point as well as of the attack angle length of line, and preferably the attack angle length of line is aft both of the moveable connection point as well as of the attack angle retractable arm.
  • the attack angle retractable arm is "sandwiched" between two slit forming plates of steel 789, i.e. upper and lower slit forming plates 789 (see FIG. 14, that is a front plan view of the pertinent portion of the trawl door of the present disclosure).
  • the warp passage slit allows the trawler's warp (not shown) to affix to the moveable connection point at the full range of motion of the moveable connection point. Otherwise, the upper and lower slit forming plates are joined at their outside edges by portions of steel plate so as to provide maximal strength to the protective shell formed by the slit forming plates.
  • the attack angle retractable arm is pivotally (i.e. hingedly) attached to either the inner side surface of the trawl door and/or to a suitable portion of the attack angle altering apparatus as described herein.
  • the hinge is designed and configured so as to permit the attack angle retractable arm to pivot in a fore to aft direction, i.e. from front to back and within the space, gap and plane defined and created by the slit forming plates as taught herein. This prevents damage to the attack angle retractable arm from shocks and other damaging forces traveling through the towing warp and trawl door during trawling operations, and also during other operations, such as seismic operations.
  • the range of motion of the moveable connection point is determined by the combination of at least (i) the length of the attack angle length of line; (ii) the maximal, minimal and intermediate positions of the attack angle retractable arm; and (iii) the distance between the base 792 of the attack angle retractable arm and the aft fixed point 793 of the attack angle length of line.
  • the moveable connection plate preferably has a bushing or sliding shim that eliminates and/or minimizes void space in the vertical orientation between the moveable connection point and the inside surfaces of the upper and lower slit forming plates, so as to prevent damage to the attack angle retractable arm attached to the moveable connection point.
  • the moveable connection point may be designed and configured so as to protrude from the extremity of the gap formed by the slit forming plates, thereby allowing unobstructed access to the moveably connection point, especially when the attack angle altering apparatus is not hingedly affixed to the remainder of the disclosed trawl door, although such hinged affixation is preferable, as taught below.
  • the moveable connection point is designed and configured so as to permit easy access to the moveable connection point, including having an aperture formed in such moveable connection point that has its hollow cavity accessible from aft and fore ends, as the upper and lower ends may be designed to fit more or less flush with the inside surfaces of the slit forming plates.
  • a length of chain, or shackles may extend from an embodiment of the moveable connection point that does not protrude without the gap formed by the slit forming plates, and the towing warp may be connected to such chain or shackle.
  • the portion of an arc of a circle capable of being defined within the slit forming plates by a pivotal movement of the attack angle length of line in a plane co- parallel to the slit moving plates is used to determine the location of a channel that is formed into the inside surfaces of both the upper and lower slit forming plates.
  • the moveable connection point has a male end that is constructed and configured to ride within such channel.
  • the slit forming plates preferably are both mounted on a hinged body, such as a super strong hinged pin, where such hinged body connects the slit forming plates and remainder of the attack angle altering apparatus to the remainder of the disclosed trawl door.
  • the hinged body permits the entire attack angel altering apparatus to pivot at its connection to the remainder of the disclosed trawl door in a vertical and/or mainly vertical direction upward and downward relative to the vertical dimension of the trawl door. This also permits maintaining an ideal orientation of the attack angle retractable arm and towing warp at various trawling depths, and also serves to preclude unbalancing forces from tipping the trawl door inward or outward.
  • the attack angle retractable arm may be loosely connected to the moveable connection point in such a fashion as to protect the attack angle retractable arm from front to aft and/or from mainly front to aft oriented shock forces transmitted through the attack angle length of line, moveable connection point and towing warp.
  • Such loosely constructed connection may include a rubber bushing between the attack angle retractable arm and the moveable connection point, or a coil spring in such position, or a leaf spring in such position, hinge, or male / female end attachment having large void spaces, a large void space ball and socket joint, or the like.
  • the attack angle retractable arm may at its connection to the moveable connection point be constructed and configured so as to have a circular opening encompassing a pin body of the moveable connection point with substantial void space to permit some movements.
  • the attack angle retractable arm In order to control the angle of attack of the trawl door, the attack angle retractable arm is shortened (retracted) in order to reduce the trawl door's angle of attack, and is lengthened (extended) in order to increase the trawl door's angle of attack.
  • the pitch of the trawl door In order to control the pitch of the trawl door, so as to maintain the trawl door's leading edge in as much a perpendicular orientation as possible relative to the oncoming water flow vector and/or relative to the direction of the trawling vessel considering the construction of the trawl door (i.e.
  • pitch variable backstrop bracket 795 is employed (see FIG. 12 and FIG. 13).
  • the pitch variable backstrop bracket includes a retractable (including “extendable”) backstrop arm 796 such as may be formed of a hydraulic ram, screw jack or worm gear having its extendable (including “retractable) linear portion either or both (i) hingedly and/or rotatably attached to the pitch variable backstrop bracket at moveable joint 800; or (ii) slideably received within a female end support sleeve 797 that is fixedly attached to the trawl door.
  • a retractable (including “extendable”) backstrop arm 796 such as may be formed of a hydraulic ram, screw jack or worm gear having its extendable (including “retractable) linear portion either or both (i) hingedly and/or rotatably attached to the pitch variable backstrop bracket at moveable joint 800; or (ii) slideably received within a female end support sleeve 797 that is fixedly attached to the trawl door.
  • the retractable backstrop arm either may be located within the structure of the trawl door, especially when the width of the profile allows for inclusion of the retractable backstrop arm within the profile of the trawl door, such as within the profile of the main deflector shown in FIG. 7.
  • the profile of the trawl door does not permit to include the retractable backstrop arm within such profile, it may be positioned on the inner side surface of the trawl door, such as on the inner side surface of the main deflector shown in FIG. 12.
  • it may be located on the outside surface of the trawl door, such as on the outer side surface of the main deflector, as shown in FIG. 13.
  • the pitch variable backstrop bracket has multiple hole options 798, is attached to the retractable backstrop arm at pitch variable backstrop bracket foot 799.
  • the pitch variable backstrop bracket foot also is slideably received through the plate and/or other structure forming the profile of the main deflector, or at least partially through such profile in the case of a bulky profile.
  • a re-enforcing structure 800 may increase the bulk, mass and strength of the main deflector's profile where such pitch variable backstrop bracket foot is slideabley received therein.
  • the pitch variable backstrop bracket By advancing toward the leading edge of the trawl door the pitch variable backstrop bracket, such as is accomplished in the instant example by retracting the retractable backstrop arm, the lowest portion of the trawl door's leading edge is advanced forward while the uppermost portion of the trawl door's leading edge is advanced backward, relative to one another.
  • the pitch variable backstrop bracket In order to reverse their positions, the pitch variable backstrop bracket is reversed and moved aft, toward the trailing edge of the trawl door, as is accomplished by extending the retractable backstrop arm.
  • the pitch of the trawl door is controlled. (Should the retractable backstrop arm be located aft of the pitch variable backstrop bracket, these sequences are reversed).
  • the entire structure of the pitch variable backstrop bracket may be included in a streamlined casing, to shield it from damage and reduce its drag.
  • Such casing preferably provides for access to the pitch variable backstrop bracket such as by being removable or having a hinged flap or door, so as to permit maintenance.
  • the pitch variable backstrop bracket is formed only at a location on a trawl door of the present disclosure that is more proximal the trawl doors upper edge than it is proximal the trawl door's lower edge, to preclude damage to the machinery of the pitch variable backstrop bracket.
  • one, two, three or all backstrop brackets on a trawl door of the present disclosure may employ such pitch variable backstrop bracket, though there only is need for one located near the top of the trawl door.
  • a trawl door tilt control apparatus 801 In order to control the tilt of the trawl door, such as often is desireable in order to accelerate the rate of ascent or descent of a trawl door of the present disclosure and thus of a trawl connected to a trawl door of the present disclosure, a trawl door tilt control apparatus 801 optionally is employed.
  • the trawl door tilt control apparatus includes a high strength hinge 804 formed of a high strength pin bolt 803 passed through multiple high strength pin bolt receiving sleeves 805.
  • the high strength hinge hinge dly connects the attack angle altering apparatus to the trawl door, preferably at the trawl door's inner side surface.
  • the trawl door tilt control apparatus includes at least one, and optionally two or more tilt varying extendable (including "retractable") arms 806, that are moveably and especially hingedly attached at moveable connections 807 to the outer sides of the slit forming plates.
  • the tilt control apparatus includes upper and lower tilt varying extendable arms 806u and 8061.
  • the tilt control apparatus In order to cause the lower portion of the trawl door to move in an outboard direction, while also causing the upper portion of the trawl door to move in an inboard direction, thereby increasing the door's propensity to rise toward the surface, either or both (i) the upper tilt varying extendable arm is retracted (i.e. shortened); and/or (ii) the lower tilt varying extendable arm is extended (i.e. lengthened). The trawl door's propensity to dive is increased in reverse order.
  • tilt varying extendable arm In order to protect any tilt varying extendable arm from damage, such tilt varying extendable arm may be contained within a protective sleeve, including a protective sleeve itself having a slideable, retractable and extendable portion.
  • the tilt varying extendable arms may be protected by a series of steel pipes extending in a front to aft orientation and bowed out from the inner side surface of the trawl door so as to form a protective cage or other barrier enclosing the tilt varying extendable arms within and between the cage and the inner side surface of the trawl door.
  • the trawl door tilt control apparatus is contained within and/or at least partially and/or mainly contained within the main deflector body of the trawl door, as indicated by dashed line cutout 809 indicating the outline of the main deflector body shown in FIG. 7.
  • the trawl door tilt control apparatus is contained within and/or at least partially and/or mainly contained within the main deflector body of the trawl door, as indicated by dashed line cutout 809 indicating the outline of the main deflector body shown in FIG. 7.
  • a longitudinal slit 810 may extend in a fore to aft direction and be designed and configured so as to permit the warp to reach the moveable connection point throughout the range of motion of the moveable connection point.
  • one or more vertically oriented slits may be provided to permit passage of the tilt varying extendable arms, such as when the slit forming plates are protruding without the profile of the trawl door and/or located external whatever portion of the trawl door they are attached to.
  • a motor or motors imparting rotation to the high strength pin bolt may be located at one or both distal ends 808 of such high strength pin bolt. By rotating such distal end, the moveable connection point is moved upward, or downward, as desired.
  • Such motor may be a hydraulic motor, electric motor, or other, geared so as to provide the needed transfer of energy so as to move the moveable connection point upward or downward.
  • vertically extendable (including retractable) arm 812 may be provided to raise or lower in a vertical direction all parts of the attack angle altering apparatus.
  • Such vertical control extendable arm 812 is affixed to rigid support brackets 814 at both ends, that themselves are fixedly attached to the trawl door and/or including its frame, and connects to the attack angle control apparatus at mounting points 815, that can be welds, bolts or other.
  • the vertical control extendable arm can be a hydraulic ram having ram arm 813, a screw jack, formed of a worm gear or other.
  • the attack angle altering apparatus is mounted to a moveable carriage that itself is slideably mounted and received to a portion of the trawl door and/or its frame.
  • One, two or more vertically extendable arms 812 raise and lower such moveable carriage upon which is mounted the attack angle altering apparatus, thus necessarily raising and lowering the moveable connection point relative to the height of the trawl door.
  • the moveable connection point is raised, thereby causing a lower trawl door section to advance relatively further outboard while an upper trawl door section moves relatively further inboard, thereby increasing climbing forces generated by the trawl door.
  • the moveable connection point is lowered.
  • the disclosed trawl door preferably is attached to trawl net bridles at backstrop brackets located near the upper and lower edges of the trawl door, including brackets not equidistant from the moveable connection point.
  • the pitch variable backstrop bracket and the tilt control apparatus may optionally be mounted upon a moveable carriage that is slideably mounted to the trawl door and/or its frame so as to provide for to aft movement of the pitch variable backstrop bracket and/or tilt control apparatus, respectively, with movement provided by one or more the retractable (including extendable)arms formed of a worm gear, screw jack, hydraulic jack, chain drive, cable drive or the like.
  • the pitch and attack angle of the trawl door, respectively are altered.
  • the moveable connection point itself may be mounted upon a moveable carriage that is slideably mounted to the trawl door and/or its frame, with movement similarly provided by similar retractable arms and the like mentioned herein, so as to provide fore to aft movement of the moveable connection point, thereby altering trawl door angle of attack.
  • the various retractable and/or extendable arms of the trawl door's attack angle altering apparatus, pitch variable backstrop bracket and tilt control apparatus are either controlled remotely or automatically.
  • Remote control can be accomplished by, for example using either wireless transmitters and/or information conductors located within a warp that then connect and communicate a first control unit located at or within the trawl door to a second control unit located aboard the trawling vessel.
  • An onboard control unit aboard the trawler may perform the function of the second control unit.
  • the second control unit may be provided with the trawl door of the present disclosure.
  • the first and second control unit can be implemented utilizing programmed general purpose processors, application specific processors, firmware, and discrete components and combinations thereof, or using remote signals.
  • Power (energy) is provided either through a remote and especially a battery source situated within and/or on the trawl door or through energy conductors located within either a warp or within the headline, bridles, and backstrops of the trawl.
  • a powered synthetic cable designed and configured as taught in published PCT application having publication number WO 2009/142766 A2, is highly useful (i.e.
  • Vectran fibers and/or other Aramid fibers are formed in another braided layer that enclosed the jacket layer formed of UHMWPE.
  • the braid angle of the Vectran and/or other Armaid fibers is greater than that used to form the enclosed jacket layer of UHMWPE, and is selected so that after heat stretching the combination of the jacket layer of UHMWPE and the layer of braided Vectran and/or other Aramid fibers enclosing the jacket layer of UHWMPE, that the final combination of both layers are balanced.
  • the UHMWPE layer has undergone permanent elongation, preferably about a supportive shaped core of thermoplastic that also has undergone permanent elongation, and also the layer of Vectran and/or other Aramid (or any fibre less elastic than UHMWPE) also has undergone permanent elongation by means of acquiring a narrower diameter, so that both layers are bearing load together more or less equally, and at least are capable of sharing load prior to the step of permanently elongating the rope formed at least of both layers.
  • Both power as well as information can be delivered, and send back to the trawler (especially information), through such synthetic cable encompassing conductors.
  • Such synthetic cable encompassing conductors can connect to the trawl door by being used as a towing warp and having its conductors pulled out of the towing warp near the warps attachment to the disclosed trawl door, made slack, and connected to the information and energy conductors of the disclosed trawl door using known water tight methods.
  • the strength member is connected to the trawl door using known methods, including splicing an eye into the end of the strength member, while preserving needed slack in the conductors.
  • information and energy may be delivered to the trawl door, and send back to the vessel (especially information), by using such synthetic cable encompassing conductors as a headline sonar cable that also splits and continues as a trawl headline, upper bridles and backstrops, thus reaching the disclosed trawl door, where again the conductors are pulled out and connected to the disclosed trawl doors conductors as mentioned supra, and so is the strength member.
  • synthetic cable encompassing conductors as a headline sonar cable that also splits and continues as a trawl headline, upper bridles and backstrops, thus reaching the disclosed trawl door, where again the conductors are pulled out and connected to the disclosed trawl doors conductors as mentioned supra, and so is the strength member.
  • energy and information are able to be delivering from the trawling vessel through the warp and/or headline sonar, headline, bridle and backstrop located information and energy conductors to the trawl door located various retractable and/or extendable arms of the trawl door's attack angle altering apparatus, pitch variable backstrop bracket and tilt control apparatus.
  • power is provided by means of a turbine generator located on the trawl door.
  • the various retractable and/or extendable arms of the trawl door's attack angle altering apparatus, pitch variable backstrop bracket and tilt control apparatus may preferably be automatically controlled.
  • the ideal angle of attack of the trawl door is programmed into the first control unit.
  • Sensors including attack angle sensors, pitch sensors and tilt sensors are in communication with the control unit.
  • the attack angle sensor constantly and/or periodically sends a signal to the control unit indicating the angle of attack of the trawl door.
  • the control unit turns on a "Retract" signal to the extendable arm of the trawl door's attack angle altering apparatus. This may include opening a "Retract" valve located on a hydraulic pump so as to move hydraulic fluid in a direction that retracts the relative arm.
  • the control unit turns on a "Extend" signal to the extendable arm of the trawl door's attack angle altering apparatus. In this way, an ideal angle of attack is maintained during turns, cross currents, heavy loading of the trawl and other disrupting events.
  • a pitch sensor constantly monitors the trawl door's pitch and either constantly or periodically sends information to the first control unit indicating the trawl door's pitch.
  • the ideal desired pitch is programmed into the control unit.
  • the control unit receives information that the trawl door is pitched upwards, it sends a "Move Aft" signal to the pitch variable backstrop bracket, which also may include either a
  • a desired tilt and/or a desired door spread is programmed into the first control unit.
  • a tilt sensor sends information to the control unit indicating the trawl door's tilt.
  • the control unit receives information that the pitch is, for example, in a "dive" orientation, it sends a signal to increase the "climb" tilt of the doors.
  • the first and second control units may be coupled, and/or the first control unit may otherwise be coupled to an onboard sonar that reads the proximity of the trawl's footrope relative to the sea bottom, or the proximity of the trawl's headline relative to the surface, and is functioning so as to maintain the trawl, its footrope and/or its headline in a desired elevation relative to the sea floor and/or sea surface. Or, it may be controlled to likewise maintain the trawl's mouth opening at a desired elevation relative to a targeted shoal of fish indicated on the sonar. However, it is suspected that in most cases skippers shall prefer to remotely operate the trawl door's tilt, while desiring to have the trawl doors angle of attack and pitch controlled automatically.
  • the control units are programmed with a "Safety" mode of operation that senses when any malfunction is occurring in the trawl door attack angle altering apparatus, pitch variable backstrop bracket and tilt control apparatus. When such malfunction is detected, the Safety mode overrides other operations of the control unit and places the trawl door into a preprogrammed desired angle of attack and tilt, especially an angle of attack considered high for a particular trawl door and a tilt considered to provide a slight net climbing force for any particular trawl door.
  • the disclosed trawl door may have a warp connection point that is attached to a carriage that itself is slideably mounted upon the inner side surface of the trawl door.
  • the carriage is slideably mounted to the trawl door with a male/female rail mounting, or similar apparatus.
  • a spring such as a coil spring, is held in place by an apparatus constructed and configured to permit the coil spring to push aft (backward) upon the carriage upon which is mounted the warp connection point.
  • the tension of the spring is adjusted so that during normal trawling for any particular vessel and trawl net, the spring is compressed to a preset maximal amount by allowing the carriage upon which is mounted the warp connection point to abut a stop plate. At this position is provided a certain desired angle of attack of the trawl door. Any event that decreases the force compressing the spring beyond a certain amount causes the spring to force in an aftward direction the warp connection point, thereby increasing the trawl door angle of attack, as is needed for example during turns.
  • FIG. 16 shows an alternative construction for an attack angle altering apparatus formed of an attack angle retractable (including extendable) arm upon which is located another moveable connection point.
  • the attack angle retractable arm may be a screw jack, worm gear or hydraulic ram having its long dimension more in line (i.e. more near to being parallel) to the chord direction line of the main deflector than it is near to being perpendicular to the chord direction line of the main deflector.
  • FIG. 17 shows an alternative construction for a combination attack angle altering apparatus and tilt altering apparatus constructed of a ball and socket joint 931 and a moveable connection point situated on the inside surface of the trawl door. This assembly can also be used to control pitch by experimental determination after having read the present disclosure.
  • the pitch variable backstrop bracket may also optionally have another retractable / extendable powered arm that changes the distance that one end of the backstrop bracket is positioned relative to the exterior surface of the trawl door, as can be used to alter trawl door pitch.
  • a hinge would need to be located at the other end of the backstrop bracket to hingeably affix that end of the backstrop bracket to the trawl door.
  • the hinge may be hidden within the profile body or located on the inner side surface of the trawl door, at the forward end of a backstrop bracket, while a hydraulic powered ram extends and retracts the aft end of the backstrop bracket further from and closer to the trawl door.
  • a hollow body that is hydrofoil shaped may be located centrally between upper and lower portions of the trawl door to serve such purpose.
  • connection point for the main towing warp 74 be positioned closer to the upper edge of the trawl door, as shown formed of upper end plate 48B than to the lower edge of the trawl door, as shown formed of lower end plate 48A. This becomes especially useful both when the trawl door has a dihedral shape as taught herein, and also when the aspect ratio of the trawl door exceeds 2:1 (two to one), and yet more critically when such aspect ratio exceeds 2.2:1 , and even yet more critically when such aspect ratio exceeds 2.4:1 , exceeds 2.55:1 and exceeds 2.7:1 .
  • the trawl door provide many options to the fishermen permitting varying the position of the connection point to the main towing warp so as to permit raising or lowering such connection point, i.e. moving it closer to or farther from the upper end plate, and also to permit moving it both in the vertical and horizontal planes.
  • FIG. 1 shows a side plan view of the inner side of the trawl door having main bale 301 .
  • the main bale includes several apertures (holes) 303 to which the main towing warp is connected, usually via a terminal length of chain having at its distal end a shackle that connects to the bale.
  • the connection point is at whatever aperture 303 is selected. Shown are two holes above the center plate, one hole level with the center plate, and one hole beneath the center plate. However, up to three, four, five, six, seven, eight, nine or even ten or more holes 303 may be situated above the center plate, i.e. are situated closer to the upper end plate than to the lower end plate.
  • Varying the connection of the towing warp relative to the body of the trawl door in the vertical plane is accomplished by selecting a hole 303, while varying the front to back, i.e. horizontal location of the connection point relative to the body of the trawl door is accomplished by alternately moving heavy duty pin bolt 306 to occupy differing holes 304, until a preferred trawl net spread, preferred drag and desired stability are obtained for a particular fishing depth, scope of main warp, rigging parameters and other conditions.
  • a preferred trawl net spread, preferred drag and desired stability are obtained for a particular fishing depth, scope of main warp, rigging parameters and other conditions.
  • several hours of initial experimentation are required when first using a trawl door of the present disclosure, after which the settings are determined and reused.
  • the trawl door of the present disclosure is a Vee shaped trawl door, as shown in FIG. 2, which is a front plan view of a trawl door of the present disclosure
  • the trawl door include several connection holes 303 situated nearer to the upper end plate than to the lower end plate and as well several holes 304, so as to permit altering both the vertical as well as the horizontal point of the connection of the towing warp to the trawl door, but also it is highly preferred that the distance from the center plate 72 to lower end plate 48A is greater than the distance from the center plate 72 to upper end plate 48B.
  • a Vee shaped trawl door includes a dihedral shape, that can have either upper and lower trawl door sections lying in different planes, with or without additional trawl door sections that may also lie in different planes or that may lie in a same plane.
  • the upper and lower trawl door sections may be joined by another trawl door section also having at least a main deflector body, where all three mentioned trawl door sections lie in different planes.
  • a longitudinal axis indicated by imaginary straight line 308 intersecting and parallel to the leading edge of an upper section of the disclosed trawl door lie within a plane that when the trawl door is viewed in a side plan view, as shown in FIG. 1 , is a same plane as lies a longitudinal axis indicated by imaginary straight line 310 intersecting and parallel to the leading edge of a lower section of the disclosed trawl door, whether there are two or more trawl door sections, and whether or not the preferred Vee shape is used.
  • "upper and lower leading edge relationship angle 316" preferably has a value of 180 degrees (one hundred eighty degrees).
  • this angle may be from 170 degrees to 188 degrees, i.e. for a "forward swept upper and lower section relationship" or for a "swept back upper and lower section relationship” embodiment of the present disclosure.
  • this angle is 180 (one hundred eighty) degrees, or at least within 6% of 180 degrees, and preferably within 5% of one hundred eighty degrees, and more preferably within 4% of one hundred eighty degrees, and yet more preferably within 3%, yet again more preferably within 2%, and yet again more preferably within 1 % of one hundred eighty degrees.
  • a longitudinal axis indicated by imaginary straight line 312 intersecting and parallel to the trailing edge of an upper section of the disclosed trawl door lie within a plane that when the trawl door is viewed in a side plan view, as shown in FIG. 1 , is a same plane as lies a longitudinal axis indicated by imaginary straight line 314 intersecting and parallel to the trailing edge of a lower section of the disclosed trawl door, whether there are two or more trawl door sections, and whether or not the preferred Vee shape is used.
  • upper and lower trailing edge relationship angle 318 preferably has a value of 180 degrees (one hundred eighty degrees). However, in some embodiments, this angle may be from 188 degrees to 170 degrees, i.e. for a "forward swept upper and lower section relationship” or for a “swept back upper and lower section relationship” embodiment of the present disclosure. However, as mentioned supra, it is most preferred that this angle is 180 (one hundred eighty) degrees, or at least within 6% of 180 degrees, and preferably within 5% of one hundred eighty degrees, and more preferably within 4% of one hundred eighty degrees, and yet more preferably within 3%, yet again more preferably within 2%, and yet again more preferably within 1 % of one hundred eighty degrees.
  • upper and lower trawl door edges in the instant example formed from upper and lower end plates, may include end plates that both (i) project outward from the profile of the primary lift generating portion of the trawl door; (ii) lie in planes that are parallel to one another or that are within 19 degrees of being parallel to one another; and (iii) include an upper end plate lying in a plane that forms with a plane within which lies the upper trawl door section an angle of lesser than ninety degrees (i.e.
  • trawl doors of the present disclosure may be connected to a main towing warp at door bridle connection point 331 using two each of upper and lower door bridle strops 332 and 334, respectively, where the upper door bridle strops are of a shorter length than the lower door bridle strops.
  • the upper and lower door bridle strops connect to or near to upper and lower end plates and/or upper and lower edges of the trawl door, respectively, at the fore and aft locations and also to the door bridle connection point.
  • a pair of middle door bridle strops connects the door bridle connection point to the trawl doors center plate 72.
  • the connection point of the trawl door to the seismic towing warp i.e. superwide, paravane line or other
  • the seismic towing warp is maintained nearer to the surface of the body of water within which is deployed the present disclosure, reducing the amount of the seismic towing warp that is submerged within such body of water, thereby reducing its drag and concurrent fuel usage.
  • a moveable/retractable trawl door bunker including at least an upper and lower bumper as well as a suitably mounted sheave located centrally in between the upper and lower bumpers and removed Inboard (i.e. away from the trawl door and toward the vessel) of the upper and lower bumpers, is employed.
  • the moveable/retractable trawl door bunker preferably is attached to the end of a crane arm that is able to be folded onto the deck with or without the door locked into the bunker, and able to be remotely extended and/or "unfolded” so as to position the trawl door into the body of water within which is operating the vessel, at a safe distance from the vessel so as to preclude vessel damage from impacts with the trawl door and also so as to allow the trawl door to be safely launched (i.e. "set") and also retrieved (i.e. "docked”).
  • the bunker In order to retrieve the trawl door, the bunker is extended outboard and positioned so as to have the towing warp pass through its sheave.
  • the towing warp is withdrawn until the trawl door is pulled firmly against the bumpers of the bunker.
  • remotely controlled arms embrace the trawl door and press it firmly against the bumpers of the bunker.
  • the entire bunker mounted on the extendable/foldable crane arm is raised and withdrawn so as to be folded either against a side of the vessel or so as to be folded and laid onto a deck of the vessel.
  • a trawl door of the present disclosure has an aspect ratio lower than 2:1 , as well as in other aspect ratios, but especially when an aspect ratio also is lower than 1 .2:1 , lower than 1 :1 , lower than 0.8:1 , lower than 0.7:1 and lower than 0.6:1 , it is especially important that the trawl door be configured so as to be adaptable for center rigging, as known in the art.
  • the instant disclosure teaches a trawl door having in combination:
  • a dihedral shape i.e. including at least upper and lower sections lying in differing planes
  • At least one steering back strop connection point that is an upper steering back strop connection point 361 designed and configured for attachment to at least one upper steering back strop 362;
  • a center back strop connection point 364 designed and configured for attachment to a centrally located back strop 365, the center back strop connection point supported by a rigid back strop fin 366 and situated further outboard from the outer side surface of the trawl door's main deflector than is situated the at least one steering back strop connection point.
  • the trawl door further includes a main bale (including main bracket, see also FIG. 1 and FIG. 2) designed and configured for attachment to a trawler's warp, wherein the main bale includes warp attachment points that are situated a different distance from the upper edge of the primary lift generating portion of the trawl door than from the lower edge of the primary lift generating portion of the trawl door.
  • a main bale including main bracket, see also FIG. 1 and FIG. 2
  • the main bale includes warp attachment points that are situated a different distance from the upper edge of the primary lift generating portion of the trawl door than from the lower edge of the primary lift generating portion of the trawl door.
  • a second steering back strop connection point that is lower steering backstrop connection point 363, one of the at least two steering back strop connection points situated nearer the upper edge of the primary lift generating portion of the trawl door than is the center back strop connection point, and the other of the at least two steering back strop connection points situated nearer the lower edge of the primary lift generating portion of the trawl door than is the center back strop connection point.
  • the center back strop connection point is situated more proximal to the most aft portion of the trailing edge of the trawl door than is situated the at least one steering back strop connection point.
  • weight shoe structure 369 and upper bumper 370 are not a part of the primary lift generation portion of the trawl door.
  • FIG. 20 is a top plan view of an alternative embodiment of profile of the trawl door of the present disclosure
  • FIG. 21 is a rear plan view of the same trawl door shown in FIG. 20.
  • FIG. 20 is a top plan view of an alternative embodiment of profile of the trawl door of the present disclosure
  • FIG. 21 is a rear plan view of the same trawl door shown in FIG. 20.
  • other disclosed features of the disclosed trawl door that are not particularly taught in reference to FIG. 20 and FIG. 21 are not shown.
  • FIG. 20 shows a side slat 372 situated adjacent to the outer side surface of the trawl door of the present disclosure.
  • the side slat preferably extends from forward or near the trailing edge of a leading edge slat, such as from forward of the trailing edge of a trailing leading edge slat, and adjacent to the outer side surface of same trailing leading edge slat, toward and to and/or near the trailing edge of the trawl door and/or trailing edge of the main deflector.
  • the side slat's overall length is preferably from 3/7 th to 6/7 th the length of the trawl door, with from 3.7/7 th to 4/7 th presently preferred.
  • the side slat may extend from the leading to trailing edges of the trawl door, or even from forward of the trawl door's leading edge to the trawl door's trailing edge, or even to aft of the trawl door's trailing edge.
  • the side slats have a concave profile and are formed of bent steel plate or other suitable material, with smooth surfaces.
  • the concave profile may be formed from an arc of a circle, or may be any other concave shape as experimentally determined useful after having read the present disclosure.
  • the concave profile may be "C" shaped, "U” shaped, "G” shaped, "V” shaped or other.
  • the side slats' concave profile includes an outer convex side facing outboard of the trawl door (i.e. facing away from the outer side surface of the trawl door), and a inner concave side facing inboard (i.e. facing toward the inner side surface of the trawl door).
  • the side slats' width 375 is from 5% to 250% the main deflector's width 377, and preferably from 50% to 80% of such main deflector's width.
  • FIG. 22 is a top plan view of yet another alternative embodiment of a trawl door of the present disclosure.
  • trawl door upper and lower sections 62 and 64 may have differing angles of attack.
  • trawl door upper section 62 can have a main deflector that has a different angle of attack than another main deflector that is a part of trawl door lower section 64.
  • the disclosed trawl door includes at least three different sections: the upper trawl door section, the lower trawl door section, and a middle trawl door section positioned between the upper and lower trawl door sections.
  • the middle trawl door section and/or its main deflector has an angle of attack that is lesser than the angle of attack of the upper and lower trawl door a sections and/or their main deflectors.
  • the upper and lower trawl door sections themselves may have different angles of attack, with for example the lower trawl door section having a greater angle of attack than the upper trawl door section, while also having a lesser angle of attack than the middle trawl door section.
  • the lower trawl door section may have a greater angle of attack than both the middle and upper trawl door section, while the middle trawl door section has a greater angle of attack than the upper trawl door section.
  • trawl doors of the present disclosure may be formed of what is known in the industry as "straight doors", i.e. trawl doors that are not dihedral shaped.
  • trawl doors of the present disclosure preferably include two or more trawl doors sections, such as a middle trawl door section and an upper and lower trawl door section, or preferably include an upper and lower trawl door section, or at least an upper and lower trawl door section, where at least the upper and lower sections lie in different planes that are neither parallel nor coplanar, with an angle of less than 180 degrees formed between the planes, and especially formed between outer side and convex surfaces of at least the main deflector bodies of at least the upper and lower trawl door sections that lie in the planes that are neither parallel nor coplanar.
  • the trawl door has only the upper and lower trawl door sections lying in the planes that are neither parallel nor coplanar, or includes other trawl door sections, it is known as a "Vee" shaped trawl door (i.e. a dihedral trawl door).
  • the upper and lower edges of that portion of the trawl door's structure designed primarily to efficiently generate lift and/or thrust are further outboard (away from the back side of the trawl door) than is the central region of that portion of the trawl door's structure designed primarily to efficiently generate lift and/or thrust.
  • Such embodiment in combination with the other teachings of the instant disclosure provide for a trawl door that is able to be maximally efficient and also able to be used at a maximal range of elevations in the water column, thereby accomplishing the objects of the present disclosure.
  • FIG. 23 shows a side plan view of a trawl door showing a useful rigging of backstrops to a trawl door that provide for continuing stability of the trawl door during catastrophic rigging failure such a backstrop rupture and/or the rupture of a bridle (including "sweep") that is connected to a such backstrop.
  • This arrangement of backstrops is known as a "W rig”.
  • the construction and the profile for the disclosed trawl door may also be used in airfoils, such as for airplanes including cargo, light and heavy aircraft, recreational, model airplanes, helicopter propeller blades, turbine blades and any other airfoil applications.
  • airfoils such as for airplanes including cargo, light and heavy aircraft, recreational, model airplanes, helicopter propeller blades, turbine blades and any other airfoil applications.
  • Several of the disclosed profiles may be useful in forming propeller blades and propeller apparatuses and assemblies for propulsion of water craft.
  • the trawl doors of the present disclosure are useful for spreading any towed in water apparatus and elements, including for mine removal and/or mine sweeping, underwater surveying and mapping, underwater monitoring of equipment, facilities and resources, and for spreading apart commercial and recreational trolling equipment, including for surface fishing of big game recreational species, and the like.

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  • Life Sciences & Earth Sciences (AREA)
  • Environmental Sciences (AREA)
  • Animal Husbandry (AREA)
  • Biodiversity & Conservation Biology (AREA)
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Abstract

L'invention concerne une porte de chalut améliorée (10) ayant un corps de déflecteur principal (24, 25) ayant des perforations en forme de fentes (110), dans laquelle la majorité de la zone perforée du corps de déflecteur principal est située dans une région du corps de déflecteur principal (24, 25) correspondant au plus à trente-deux pour cent de la longueur de corde du corps de déflecteur principal (24, 25) et les perforations (110) sont conçues de sorte que les perforations (110) comprennent un angle (127) inférieur à quatre-vingt-deux degrés, l'angle étant mesuré entre la majorité de la ligne d'axe de dimension longue de chaque perforation (120) et une ligne droite imaginaire (88) reliant la distance la plus courte entre les bords d'attaque et de fuite (42, 14) du corps de déflecteur principal (24, 25), ces lignes étant vues dans un même plan.
PCT/EP2011/056674 2010-04-27 2011-04-27 Porte de chalut perforée et procédés WO2011135006A1 (fr)

Applications Claiming Priority (6)

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US34332310P 2010-04-27 2010-04-27
US61/343,323 2010-04-27
EPPCT/EP2010/063499 2010-09-14
PCT/EP2010/063499 WO2011029958A1 (fr) 2009-09-14 2010-09-14 Panneau de chalut à efficacité élevée, à stabilité élevée et à élévations multiples, et procédés
US201161460537P 2011-01-03 2011-01-03
US61/460,537 2011-01-03

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Publication number Priority date Publication date Assignee Title
NO20161687A1 (en) * 2016-10-25 2018-04-26 Polarcus Dmcc A bridle for a marine deflector
CN108347910A (zh) * 2015-09-14 2018-07-31 新拖网门设计有限公司 翼型形状拖网网板
NO20171262A1 (no) * 2017-07-28 2019-01-29 Remoey Sea Group As Anordning for å optimalisere stillingen til en trål og å styre trålen
EP3671286A1 (fr) * 2018-12-18 2020-06-24 PGS Geophysical AS Ajustement de l'angle d'un déflecteur par rapport à un navire d'enquête marine
EP3562301A4 (fr) * 2016-12-29 2020-08-05 Mld Aps Panneau de chalut avec de nouveaux points de fixation a tirer derrière un vaisseau
EP4066634A1 (fr) * 2021-03-23 2022-10-05 Volu Ventis ApS Panneaux de chalut contrôlables et leur procédé de commande

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NO20161687A1 (en) * 2016-10-25 2018-04-26 Polarcus Dmcc A bridle for a marine deflector
NO342333B1 (en) * 2016-10-25 2018-05-07 Polarcus Dmcc A bridle for a marine deflector
EP3562301A4 (fr) * 2016-12-29 2020-08-05 Mld Aps Panneau de chalut avec de nouveaux points de fixation a tirer derrière un vaisseau
NO20171262A1 (no) * 2017-07-28 2019-01-29 Remoey Sea Group As Anordning for å optimalisere stillingen til en trål og å styre trålen
NO344688B1 (no) * 2017-07-28 2020-03-09 Remoey Sea Group As Anordning for å optimalisere stillingen til en trål og å styre trålen
EP3671286A1 (fr) * 2018-12-18 2020-06-24 PGS Geophysical AS Ajustement de l'angle d'un déflecteur par rapport à un navire d'enquête marine
US11048003B2 (en) 2018-12-18 2021-06-29 Pgs Geophysical As Bridle bite adjustment
EP4066634A1 (fr) * 2021-03-23 2022-10-05 Volu Ventis ApS Panneaux de chalut contrôlables et leur procédé de commande

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