WO2003000043A2

WO2003000043A2 - Stable, stronger, lower bulk and drag netting

Info

Publication number: WO2003000043A2
Application number: PCT/US2002/019648
Authority: WO
Inventors: Sherif Adham Safwat; Valentin Gavrilovich Perevoshchikov
Original assignee: Sherif Adham Safwat; Perevoshchikov Valentin Gavril
Priority date: 2001-06-25
Filing date: 2002-06-21
Publication date: 2003-01-03
Also published as: AU2002345745A1; WO2003000043A3; US20040251688A1

Abstract

The present invention includes an improved method of making knotted netting panels (62) in which pairs of mesh bars (66) are knotted at intersections between lines (22, 34). The improved method includes forming a first loop (24) in the line (22) through which the line (34) helixes to form a second loop 36). Another aspect is improved knotted netting which includes at least two continuous lengths of line (22, 34) that form pairs of mesh bars (66) that are knotted together using the knot described above. A final aspect of the invention is an improved trawl that includes improved knotted netting made from twines (22, 34) that have a lay direction (IIZ' or lIS'). The lay direction (IIZ' or lIS') of twines (22, 34) are opposite to the direction (lIS' or IIZ') of loops forming the knots. Cambered sections (41) in the lay direction twines (22, 34) which face outward from an outer surface of the improved trawl are oriented generally toward the front and back of the trawl.

Description

STABLE, STRONGER, OWER BULK AND DRAG ETTING

The present invention relates generally to the technical field of netting and, more particularly, to netting useful for fishing.

Background Art

The weaver's knot is the most common coupling used in making fishing nets for joining together two twines. With netting twine that has a rough surface (vegetable fibers, synthetic staple fibers, and split fibers) , this knot provides sufficient knot stability, i.e. resistance to slippage. Netting twines made of continuous filaments and monofilaments have a very smooth surfaces, particularly when twisted. Therefore, weaver's knots formed with such materials tend to slip. Such knot slippage yields netting in which meshes may be unstable during use, and therefore may have differing mesh shapes and mesh sizes. Knot instability is disadvantageous for various different uses for fish netting. Knot instability is most undesirable for gillnets where the catch depends on mesh which has a certain size opening. Knot instability is also disadvantageous for many other types of fishing gear such as trawls. For trawls, knot instability adversely affects:

1. a proper distribution of stress in the netting which prevents local overloading of the netting that leads to netting failure;

2. correct hanging of netting on lines; and 3. a particular designed shape for the trawl.

Trawl performance degrades if netting hangs incorrectly on lines or if the trawl net looses its shape. Lastly, knot slippage may increase fatigue failure of netting due to additional wear of the netting's twines by rubbing against each other.

Seeking to reduce knot slippage, netting manufactures may suitably treat the netting in various different ways such as those described in United States Patent nos. 2,590,596 and 4,457,959. Alternatively, netting manufacturers may use a double weaver's knot instead of the conventional, single weaver's knot. The double weaver's knot, which can be machine braided, provides netting with sufficient knot stability even when it is made with difficult materials' such as thick monofilaments. However, compared to the single weaver's knot, the double weaver's knot has the disadvantages of larger weight and bulkiness, both of which adversely affect netting's manufacturing cost and performance. Instead of the normal weaver's knot or the double weaver's knot, to provide increased knot stability reportedly some fish netting, particularly netting made in Japan, uses the square knot, also sometimes identifies as the reef knot.

In addition to their ability to resist slippage, knots used in making fish netting are also evaluated for how little they degrade the breaking strength of un-knotted twines. Most of the machine-made knotted netting in trawls is single knot netting using the traditional weaver's knot. Measured using the "4-leg-one-knot" standard knot breaking strength test, the weaver's knot usually preserves less than half (50%) of the breaking strength value measured for un-knotted twines. Measured using a "diagonal" breaking strength test, the weaver's knot generally preserves even less of the breaking strength value measured for un-knotted twines. Furthermore, the mesh breaking strength of all netting tied using the weaver's knot, which can be determined only using meshes made with non-slipping knots, is 10 to 25% lower than a breaking strength measured for a single knot. It has been reported that the lower breaking strength exhibited by netting in comparison with knot breaking strength is due to the lower breaking strength exhibited by one of four knots included in each netting mesh cell.

For trawl netting it is most important to maximize the strength of the netting along the mesh bars, i.e. the diagonal direction, as opposed to the "4-leg-one-knot" direction commonly used in measuring knot breaking strength. Presently available nettings bear load unsatisfactorily along parallel mesh bars, i.e. "along the bar." That is, the strength of netting along the bar compared to the un-knotted, straight-line breaking strength of twines making up the netting is disappointingly low.

Maximizing breaking strength along the bar is necessary because during fishing, strain loads are borne almost exclusively along the bar. In conventional diamond-shaped netting construction, rarely are equal forces applied concurrently to both mesh bars making up one-half of a mesh cell. Rather, because load forces in trawls are borne by the netting in a direction having a primary component transverse to the trawl's length, load is almost exclusively borne along the diagonal direction of the netting on one of the two mesh bars mesh bars emanating from each knot. For seine nets, similarly load forces are primarily directed transverse to either the short or long direction of the net. Consequently, the limiting factor is a netting's ability to bear load along the bar.

To reduce possible knot slippage during use, trawl nets are designed with significantly heavier and more massive netting than needed for load which the netting should need to bear based upon results reported for the "4-leg-one-knot" test. The use of heavier netting seeks to assure preserving trawl nets shape by avoiding knot slippage. Consequently, there remains an unfilled need in the industry for netting that can bear much higher loads along the bar without knot slippage, while also exhibiting equal or even greater strength in the "4- leg-one-knot" test without increasing knot size or material consumption.

Despite the preceding disadvantages, in addition to bridles, frontropes, wings, and riblines, trawls are assembled primarily using knotted netting. Specifically, the vast majority of knotted netting used in trawls is single knot netting made with the' traditional weaver's knot. As stated previously, using the standard "4-leg-one-knot" breaking strength test, this conventional knot retains usually less than one-half (50%) of the breaking strength exhibited by twines forming the knot. Moreover, the weaver's knot retains an even lesser amount of strength when netting breaking strength is measured using the "diagonal" breaking strength test, or along the bar break direction.

In an attempt to ensure a minimum netting strength after a specified interval of use and to thereby avoid fatigue failure, newly manufactured conventional knotted netting must be much stronger initially than the minimum strength required at the end of the netting's service life. The additional material required so conventional netting avoids fatigue failure and thus guarantees a minimum strength after a specified interval of use increases the netting's bulk which correspondingly increases the netting' s hydrodynamic drag and the cost of manufacture.

Netting manufacturers employ various techniques in attempting to improve fatigue resistance, i.e. improve the resilience, of machine-made netting. One technique used to improve fatigue resistance is incorporating a larger sized knot, e.g. double knotting, at junctures between individual twines that form the cell bars of conventional knotted netting. The principle underlying the use of larger sized knots is that intersecting twines forming larger knots have a larger bend radius which distributes load on the twines more uniformly across the twines entire cross-section. Thus, it is widely believed in the netting industry that one way to obtain a greater strength retention from a given twine used in machine- knotted netting is to increase knot size, either by doubling the twines (i.e. two parallel twines in place of one), or by making a double knot. However, while it is widely believed that the larger the knot the stronger the netting, it is also widely believed that the larger the knot, the greater the netting's hydrodynamic drag. Consequently, this particular solution for improving fatigue failure increases netting hydrodynamic drag in order to provide netting that is stronger and exhibits resilience.

Moreover, conventional machine-made knotted netting is a commodity product with numerous manufacturers competing in offering their products to the same group of potential purchasers. Thus, a desirable characteristic for conventional machine-made knotted netting is that it have low manufacturing cost.

In comparison with knotted netting, knotless nettings also bear load poorly along the bar and tear easily. Thus, knotless netting is disfavored for trawl and most seine net applications. For this and other reasons, including greater bycatch, knotless netting has not been widely adopted for such applications.

The aforesaid problems applicable, to trawl netting also apply in general to netting used in seines, and other nets.

Disclosure of Invention

DEFINITIONS

DIAMETER as used herein for a characteristic of twines means a twine having any cross-sectional shape that has a cross-sectional area which equals the cross-sectional area of a twine having a circular cross-sectional shape with the stated diameter. MESH BAR as used herein means the sides of a mesh cell excluding knots or other types of couplers used instead of knots.

MESH CELL as used herein means the sides of a mesh and includes at least three sides and associated knots or equiva- lent couplers oriented in space. A quadratic mesh cell, square or diamond shaped, has four sides with four knots or couplers, and is usually arranged to form a parallelogram, with diamond-shaped mesh (trawl mesh) being preferred. A triangular mesh cell has three sides and three knots or couplers. A hexagonal mesh cell has six sides and six knots or couplers. MESH SIZE as used herein means the distance between knots or couplers that are located on opposite sides of a square mesh cell when the mesh cell is completely closed. Thus a measurement of mesh size as used herein is approximately equal to the length of two mesh bars arranged end-to-end.

TWINE as used herein means a strong string or cord that is woven or braided from materials such as synthetic or natural fibers, or any combination thereof. An object of the present invention is to provide a stable knotted netting that, when tested using the standard "4-leg- one-knot" breaking strength test, exhibits a breaking strength which equals or exceeds the breaking strength of conventional, single knot netting.

Another object of the present invention is to provide a stable knotted netting that is stronger along mesh bars than conventional, single knot netting.

Another object of the present invention is to provide a stable knotted netting that is stronger along mesh bars than conventional, single knot netting while also having a comparatively small knot.

Another object of the present invention is to provide a stable knotted netting that retains a greater proportion of the straight line breaking strength of twines included in the netting.

Another object of the present invention is to provide a stable knotted netting that, while having a strength which equals or exceeds the strength of conventional, single knot netting, requires less twine material.

Another object of the present invention is to provide a stable knotted netting that, while having a strength which equals or exceeds the strength of conventional, single knot netting, exhibits less hydrodynamic drag. Briefly, one aspect of the present invention is an improved method of making knotted netting that includes mesh cells having pairs of mesh bars fabricated from at least two continuous lengths of twine. In such knotted netting, pairs of mesh bars in each mesh cell are knotted at intersections between twines. The improved method of making knotted netting includes the following knotting steps. a) In Step 1, forming a first of the twines into a closed first loop thereby establishing a region in a standing portion of the first twine in which the first twine is doubled. b) In Step 2, passing a tag end of a second of the twines through the first loop. c) In Step 3, helixing the tag end of the second twine around the region in the standing portion of the first twine in which the first twine is doubled to again pass for a second time through the first loop thereby establishing a second loop in the second twine . d) In a final Step, tightening a knot that now couples together the first and second twines as established by steps a) through c) above by pulling on all sections of both twines extending away from the knot.

Another aspect of the present invention is an improved knotted netting which includes at least two continuous lengths of twine. Portions of these twines form pairs of mesh bars that are included in mesh cells. In the improved netting, knots of the type described above join together mesh bars of mesh cells. Because the improved knots preserve a greater proportion of the straight line breaking strength of twines included in the netting, the improved netting, while having a strength which equals or exceeds the strength of conventional, single knot netting, requires less twine material, and exhibits less hydrodynamic drag.

Yet another aspect of the present invention is an improved trawl, which includes bridles, frontropes, wings, and riblines, and which also includes the improved knotted netting that is made from twines that having a lay direction ("Z" or "S") . In the improved netting made from twines that have a lay direction, the lay direction ("Z" or "S") of twines used for forming the improved netting are opposite to the direction ("S" or "Z") of loops formed respectively in the first and second twines. Furthermore, for twines that have a lay direction, cambered sections that are present on such twine and that face outward from an outer surface of the improved trawl are oriented generally toward the front and back of the trawl. An advantage of the knotted netting of the present invention is that it permits fabricating stable diamond mesh and square mesh netting in which two, and sometimes more, lines that have equal or dissimilar diameter, connect together. These and other features, objects and advantages will be understood or apparent to those of ordinary skill in the art from the following detailed description of the preferred embodiment as illustrated in the various drawing figures.

Brief Description of Drawi gs

FIGs. la-lc provide a sequence of elevational views which depict forming a knot in accordance with the present invention;

FIG. 2 is a plan view illustrating one testing configu a- tion for the standard "4-leg-one-knot" breaking strength test;

FIG. 3 is a plan view illustrating a testing configuration used both for a "diagonals" breaking strength test and for a knot slippage test;

FIG. 4 is an elevational view which depicts forming a knot in accordance with the present invention from twines that have specified lay directions;

FIG. 5 is an elevational view which depicts forming a knot in accordance with the present invention from multiple twines;

FIG. 6 is an elevational view which that depicts a knot formed in accordance with the present invention in which the first line has multiple loops;

FIG. 7 is an elevational view which that depicts a knot formed in accordance with the present invention in which both, the first and the second lines have multiple loops; FIG. 8 is a plan view illustrating a set of jigs used to facilitate hand assembly of netting panels which use a knot in accordance with the present invention upon which have been arranged twines that form the knot's first line; and

FIG. 9 is a plan view illustrating the set of jigs and first lines that are depicted in FIG. 8 upon which have been arranged additional twines that form the knot's second line.

Bes Morig for Carrying Out t.he> Tnv.n ion

FIGs. la through lc illustrate one way of tying a preferred embodiment of a knot, identified by the general reference character 20 in FIG. lc, in accordance with the present invention. FIG. la illustrates a first step, i.e. Step

1, in tying the knot 20 which consists in forming a first line 22 into a closed first loop 24. A tag end 26 of the first line 22, indicated by a curved arrow line T, that is located on one side of the first loop 24 extends parallel to and is directed away from a first section 28 of the first line 22 that is located on an opposite side of the first loop 24. The first line 22 depicted in FIG. la, excluding the tag end 26, forms a standing portion of the first line 22 which is doubled throughout a region 29 thereof. As depicted in FIG. la, the first loop 24 extends rightward from the region 29 in which the first line 22 is doubled, and the tag end 26 of the first line 22 passes behind the first section 28 in the region 29.

A second step, i.e. Step 2, in forming the knot 20 that is depicted in FIG. lb consists in passing a tag end 32 of a second line 34 leftward through the first loop 24 in the first line 22, in front of the first loop 24 and behind the region 29 in which the first line 22 is doubled.

A third step, i.e. Step 3, in forming the knot 20 that is depicted in FIG. lc consists in helixing the tag end 32 of the second line 34 around the region 29 in which the first line 22 is doubled, and back through the first loop 24 above the second line 34 thereby establishing a second loop 36.

In the illustration of FIG. lc, the first loop 24 of the first line 22 turns in an "S" direction while the second line 34 helixes around the region 29 irt a "Z" direction. A knot 20 in accordance with the present invention may be formed with the first loop 24 and the second loop 36 having the same direction, i.e. both. of the loops 24, 36 having the same turn direction "S" or "Z". However, to maximize performance of the knot 20 it is important that the turn directions of the loops 24, 36 formed respectively in the first line 22 and in the second line 34 be opposite, one loop having an "S" turn direction and the other loop having a "Z" turn direction.

A fourth step in forming the knot 20, i.e. Step 4, that ' is not depicted in any of the FIGs., which need not be performed immediately after forming the knot 20, consists in tightening the knot 20 by pulling on all sections of both lines 22, 34 extending away from the knot 20. While pulling on all sections of the lines 22, 34, the knot 20 must be held to impede slippage of the lines 22, 34 during tightening. In addition to pulling on all sections of the lines 22, 34 that extend outward from the knot 20, if desired making netting using the knot 20 may include further, additional processing operations adapted for "setting" the knot 20.

Most twines used in making conventional netting may be tied using the knot 20. When tightened well, the knot 20 does not slip, and as set forth in the following table exhibits greater strength than the conventional weaver's knot. Twines having a construction which during the normal knotting process readily adapts to the shape of the knot 20 of the present invention form strong knots. When tested for breaking strength along the bar, twines tied with the knot 20 frequently exhibit twice as much strength for the same material as knots tied using the weaver's knot.

The preceding table compares breaking strength values for the knot 20 of the present invention with the standard weaver's knot using the standard "4-leg-one-knot" breaking strength test depicted in FIG. 2. As depicted in FIG. 2, both sections of each of the lines 22, 34 are respectively fastened to a block 42 and the blocks 42 drawn apart as indicated by a double- headed arrow 44 until the knot breaks. This standard "4-leg- one-knot" break test may be performed either with the legs diverging at a pre-selected angle, or with the legs disposed parallel to each other as illustrated in Figures 18, 19a and 19b of "Netting Materials for Fishing Gear, " second edition, by Gerhard Klust copyrighted 1973, 1982 Food and Agriculture Organization of the United Nations.

The Euroline and Eurolάne Premium materials identified in the preceding table are made by Euronete, S.A. of Maia, Portugal. The Alnet materials identified in the preceding table are made by Alnet (Pty) Ltd. of Cape Town, South Africa. The nylon materials identified in the preceding table are commercially-available, purchased twines. The breaking strength values presented in the preceding table are measured to an accuracy of ±5 kg. The knots 20 formed in Euroline, Euroline Premium and ^" Alnet polyethylene materials were tightened to 75% of their breaking strength before performing the breaking strength test.

The preceding table also compares breaking strength values for the knot 20 of the present invention compared with the standard ^• weaver ' s knot "along the bar" using a "diagonal" breaking strength test illustrated in FIG. 3. The "diagonal" breaking strength test differs from the standard "4-leg-one- knot" breaking strength test in that in the "diagonal" test tension is applied to only a pair of essentially collinear legs extending outward from the knot. The legs of the knot that are respectively secured to the blocks 42 are those that would form an essentially collinear pair of mesh bars in a sheet of netting. In the test depicted in FIG. 3, the legs formed by the lines 22, 34 which are disconnected from the blocks 42 hang freely from the knot. In a sheet of netting, the freely hanging legs of the lines 22, 34 form a second pair of essentially collinear mesh bars that intersects with the mesh bars formed by the legs of the knot that are fastened to the blocks 42, The testing configuration depicted in FIG. 3 is also used for measuring the force required for knot slippage.

All weaver's knots tied using the materials listed in the preceding table slip when tested in the configuration depicted in FIG. 3 at an applied force which is less than that required to break the weaver's knot. Thus, obtaining the weaver's knot breaking strength test values set forth in the preceding table for the "diagonals" breaking strength test requires securing something around the freely hanging legs of the weaver's knot which prevents knot slippage.

As indicated by the breaking strength values listed in the preceding table, breaking strength values in the load bearing direction, i.e. along the bar, in fishing gear, i.e. the diagonal, for the knot 20 are surprisingly, substantially greater than for the traditional weaver's knot used in conventional machine-made netting. Thus, due to the greater twine strength retention provided by the knot 20, use of the knot 20 in making conventional netting instead of the weaver's knot permits reducing the amount of material required for equivalent strength netting.

Please note that the breaking strength values presented in the preceding table were not taken using industry standard clamps for securing the lines 22, 34. Therefore, it appears unlikely that the values reported in the preceding table match precisely breaking strength values reported by netting manufacturers . However, even though the breaking strength values reported in the preceding table may not match precisely the breaking strength values reported by netting manufactures, the relative improvement in breaking strength provided by the knot 20 should be independent of such details of the testing procedure. The following table compares the amount of force that must be applied to produce a specified amount of slippage for the traditional weaver's knot and for the knot 20 of the present invention. Because the knot 20 does not slip, the values reported for its slippage are the same as those reported for the "diagonal" breaking strength for the knot 20. Since the weaver's knot made with polyethylene exhibited some slippage before reaching the knot's breaking strength measured using the "diagonal" test, the resistance to slippage exhibited by the knot 20 is several times greater than that measured for the traditional weaver's knot. Consequently, for those fishing gear applications of conventional machine-made netting in which resistance to knot slippage determines a diameter for the twines used in making the netting, e.g. trawls, use of the knot 20 offers an opportunity for even further significantly reducing the amount of material required for the netting which correspondingly reduces the netting's bulk.

Due to the slippage characteristics of weaver's knots tied using nylon materials, as indicated by the abbreviation "NP" is was not possible to obtain 10 mm and 20 mm slippage data for those materials.

If the knot 20 is to be formed in twines that have a lay direction as contrasted with twines that do not have a lay direction such as braided twines, then there exists a preferred orientation for the lays which maximizes stability of the knot 20. As illustrated in FIG. 4 the fundamental principle for lay orientation for the lines 22, 34 which maximizes stability of the alternative embodiment of the knot 20 depicted in that FIG. is that the lay directions of twines used for forming the knot 20 preferably are opposite to the direction ("S" or "Z") of loops formed respectively in the lines 22, 34. As depicted in FIG. 4, since the first loop 24 formed in the first line 22 turns in an "S" direction, the first line 22 preferably has a "Z" lay. Analogously, since the second line 34 loops around the region 29 in a "Z" direction, the second line 34 preferably has a "S" lay. The preceding relationship between the turn direction of a line's loop and the lay construction of a twisted twine used in forming that line is important for maximizing the stability of the knot 20 and of netting knitted using the knot 20.

If twines having lay directions such as those depicted in FIG. 4 are to be used together with the knot 20 to make diamond shaped trawl meshes, the twines are preferably oriented and arranged so that cambered sections 41, i.e. grooves that occur between substrands of the twines, located on the outside of a trawl are oriented generally parallel to a flow vector for water that flows past the trawl. Consequently, the cambered sections 41 on the inside of the trawl are oriented generally orthogonal to the water flow vector. Stated in another way, the cambered sections 41 on the outer surface of the trawl are oriented generally toward the front and back of the trawl, while the cambered sections 41 on the inner surface of the trawl- are oriented generally parallel to a cross-section of the trawl .

FIG. 5 depicts another alternative embodiment of the knot 20 that is formed by a pair of first lines 22a, 22b and by a pair of second lines 34a, 34b. The construction of knots 20 of the general type depicted in FIG. 5 is particularly useful for interconnecting meshes of differing sizes. For example, this construction is useful for batings, where a mesh of a certain size connects to a mesh of smaller size or of half size. In that particular application, to smoothly transition to a smaller size twine and to smaller size and larger number of meshes, smaller and larger size twines are laid alongside each other just ahead of the knot 20 to form either or both of the lines 22, 34. Moreover, more than two twines may be included in each of the composite lines 22, 34. For example, a larger twine, and two smaller twines may be used for each of the lines 22, 34. After the knot 20 has been formed using two or more twines for each of the lines 22, 34 and tightened, the portion of the tag ends of larger twines may be cut and removed leaving the two smaller twines in each tag end either to:

1. continue into the next knot 20 in the net; or

2. branch off separately and continue into two separate knots 20 as when increasing the number of meshes as at a bating. FIG. 6 depicts yet another alternative embodiment of the knot 20 in which the first line 22 has been formed into a double first loop 24 instead of the single loop illustrated in FIG. 1. In all other respects the knot 20 depicted in FIG. 6 is identical to the knot 20 depicted in FIG. 1. Thus, the turn directions of the double first loop 24 in the first line 22 must retain the same relationship as that described for the single first loop 24 depicted in FIG. 1. Mesh bars of netting that are formed by the first line 22 tied into the double loop knot 20 depicted in FIG. 6 exhibit unusually high "diagonal" breaking strength in comparison with the "diagonal" breaking strength of knots 20 listed in the first of the preceding tables . FIG. 7 depicts yet another alternative embodiment of the knot 20 in which both the first line 22 and the second line 34 have been formed into a double loops instead of the single loop illustrated in FIG. 1. In all other respects the knot 20 depicted in FIG. 7 is identical to the knot 20 depicted in FIG. 1. Thus, the turn directions of both double loops in the knot 20 depicted in FIG. 7 must preserve the relationships described for the single first loop 24 depicted in FIG. 1. All mesh bars of netting that are formed by the first line 22 tied into the double-double loop knot 20 depicted in FIG. 7 exhibit unusually high "diagonal" breaking strength in comparison with the "diagonal" breaking strength of knots 20 listed in the first of the preceding tables. As stated previously, since the load in netting meshes of trawls is often primarily along the diagonal mesh bars, high breaking strength in those directions is advantageous.

Industrial Applicability

The plan view of FIG. 8 depicts four elongated jigs 52 which extend horizontally across that FIG. that are adapted to facilitate hand assembly of netting panels. Such netting panels are frequently used in midwater trawls, particularly for mesh sizes that exceed one (1.0) meter in length. Each jig 52 includes a uniformly spaced row of pegs 54 which project upward out of FIG. 8. After the netting panel has been assembled, one knot 20 will be formed at each of the pegs 54. Spacing between the pegs 54 on each jig 52, and between the jigs 52 establishes a size for mesh cells of the netting panel. In the illustration of FIG. 8, lengths of twine, each of which constitutes one of the first lines 22 illustrated in FIGs. la-lc and other FIGs., have been prestrung across the jigs 52 with a series of first loops 24 formed in each first line 22 encircling one peg 54 on each of the jigs 52. In the finished netting panel, each of the first lines 22 forms one essentially collinear row of rnesh bars that traverse the netting panel diagonally.

FIG. 9 illustrates a subsequent step in assembling the netting panel in which twines that form the second lines 34 have been inserted through the first loops 24 at each peg 54 and looped around the doubled first line 22 that forms the first loop 24. In a' finished netting panel 62, each of the second lines 34 forms one essentially collinear row of mesh bars that cross the netting panel 62 diagonally intersecting at knots 20 mesh bars formed by the first lines 22. As described previously in connection with the description of FIGs. la-lc, all that remains to complete the netting panel 62 after the second lines 34 have been arranged as depicted in FIG. 9 is tightening each individual knot 20.

The portion of a completed netting panel 62 depicted in FIG. 9 depicts two rows of complete, diamond-shaped mesh cells 64. Each mash cell 64 includes four mesh bars 66 each of which spans a distance between two immediately adjacent knots 20. As is readily apparent from the illustration in FIG. 9, each mesh bar 66 belongs to two mesh cells 64 which abut each other along their common mesh bar 66.

FIG. 9 illustrates a significant characteristic of the netting panel 62 which distinguishes netting made in accordance with the present invention from conventional machine-made netting tied with the weaver's knot. In conventional machine- made netting tied with the weaver's knot, each continuous twine in the netting zig-zags back and forth across the netting panel, and is knotted first to one and then to another of a pair of adjacent twines in forming a single mesh bar. In netting made in accordance with the present invention the lines 22, 34 extend in substantially straight lines across the netting panel 62 with any selected pair of the lines 22, 34 being knotted to each other at only a single intersection at ends of only one pair of mesh bars 66.

Although the present invention has been described in terms of the presently preferred embodiment, it is to be understood that such disclosure is purely illustrative and is not to be interpreted as limiting. For example, while the description for forming the knot 20 in the text that is associated with FIGs. la-lc describes first forming the "S" direction first loop 24 in the first line 22 and then helixing the second line 34 around the region 29 in the "Z" direction to form the second loop 36, the lines 22, 34 may be equivalently knotted by first forming a "Z" direction loop in the second line 34 and then helixing the first line 22 in an "S" direction around a doubled region of the second line 34. Analogously, when assembling a netting panel 62 using the jigs 52, the lines 22, 34 may be arranged to form single or multiple loops 24, 36 in accordance with the illustrations of FIGs. la-lc, 6 and 7 or any equivalent variation thereof. While the illustrations for making netting in FIGs . 8 and 9 depict first uniformly forming the "S" direction first loops 24 in the first lines 22 and then helixing the second lines 34 in the "Z " direction to form the second loops 36, it may be advantageous, particularly for machine manufactured netting, to vary the orientation of the loops 24, 36 thus having both "S" and "Z" direction loops along individual first lines 22 and second lines 34. As is readily apparent, such a variation in the orientation of the loops in one of the lines 22 or 34 necessarily requires a corresponding variation in the orientation of loops in the other line 34 or 22 to preserve the opposite turn direction required for pairs of loops 24, 36 forming each of the knots 20. Varying in this way loop orientations used in forming knots 20 throughout a netting panel 62 may be advantageous for balancing torque within the netting panel 62 to obtain essentially torque balanced (torque free) netting.

Consequently, without departing from the spirit and scope of the invention, various alterations, modifications, and/or alternative applications of the invention will, no doubt, be suggested to those skilled in the art after having read the preceding disclosure. Accordingly, it is intended that the following claims be interpreted as encompassing all alterations, modifications, or alternative applications as fall within the true spirit and scope of the invention.

Claims

\The ClaimsWhat is claimed is:

1. An improved method of making knotted netting that includes mesh cells having pairs of mesh bars fabricated from at least two continuous lengths of twine, pairs of mesh bars of each mesh cell being knotted at intersections between twines, the improved method of making knotted netting comprising the knotting steps of: a) forming a first of the twines into a closed first loop thereby establishing a region in a standing portion of the first twine in which the first twine is doubled; b) passing a tag end of a second of the twines through the first loop; c) helixing the tag end of the second twine around the region in the standing portion of the first twine in which the first twine is doubled to again pass for a second time through the first loop thereby establishing a second loop in the second twine; and d) tightening a knot that now couples together the first and second twines as established by steps a) through c) above by pulling on all sections of both twines extending away from the knot.

2. The improved method of claim 1 wherein the first loop and of the second loop have opposite turn directions ("Z" and "S") .

3. The improved method of claim 1 or 2 wherein at least one of the twines has a lay direction ("Z" or "S") , further comprising the step of selecting the lay direction of the twine to be opposite to a direction ("S" or "Z") of the loop formed in the twine.

4. The improved method of claim 1 or 2 further comprising the step of juxtaposing at least one additional twine throughout the knot with at least one of the twines .

5. The improved method of claim 1 or 2 further comprising the step of, before tightening the knot, forming another loop in the first twine that is juxtaposed throughout the knot with the first loop formed therein.

6. The improved method of claim 1 or 2 further comprising the step of, before tightening the knot, forming another loop in the second twine that is juxtaposed throughout the knot with the second loop formed therein.

7. An improved netting comprising: at least two continuous lengths of twine, portions of said twines forming pairs of mesh bars that are included in mesh cells; and knots that join together mesh bars of mesh cells, each of said knots being established by: a) forming a first of the twines into a closed first loop thereby establishing a region in a standing portion of the first twine in which the first twine is doubled; b) passing a tag end of a second of the twines through the first loop; c) helixing the tag end of the second twine around the region in the standing portion of the first twine in which the first twine is doubled to again pass for a second time through the first loop thereby establishing a second loop in the second twine; and d) tightening each knot that now couples together the first and second twines as established by the preceding operations a) through c) by pulling on all sections of both twines extending away from said knot.

8 „ The improved netting of claim 7 wherein the first loop and of the second loop have opposite turn directions ("Z" and "S") .

9. The improved netting of claim 7 or 8 wherein at least one of the twines has a lay direction ("Z" or "S"), and the lay direction of the twine is opposite to the direction ("S" or "Z") of the first loop formed in the twine.

10. The improved netting of claim 7 or 8 wherein at least one of the twines forming at least one of the knots in the improved netting further comprises another twine which is juxtaposed with that twine throughout the knot.

11. The improved netting of claim 7 or 8 wherein, before tightening the knot, a another loop is formed in the first twine that is juxtaposed throughout the knot with the first loop formed therein.

12. The improved netting of claim 7 or 8 wherein, before tightening the knot, a another loop is formed in the second twine that is juxtaposed throughout the knot with the second loop formed therein.

13. An improved trawl which includes bridles, frontropes, wings, and riblines, wherein the improvement comprises knotted netting that includes : at least two continuous lengths of twine, portions of said twines forming pairs of mesh bars that are included in mesh cells, at least one of said twines having a lay direction ("Z" or "S"); and knots that join together mesh bars of mesh cells, said knots being established by: a) forming a first of said twines into a closed first loop thereby establishing a region in a standing portion of the first twine in which the first twine is doubled; when th'e first twine has a lay direction, the lay direction being opposite to the turn direction of the first loop; b) passing a tag end of a second of said twines through the first loop; c) helixing the tag end of the second twine around the region in the standing portion of the first twine in which the first twine is doubled to again pass for a second time through the first loop thereby establishing a second loop in the second twine; when the second twine has a lay direction, the lay direction being opposite to the turn direction of the second loop; and d) tightening each knot that now couples together the first and second twines as established by the preceding operations a) through c) by pulling on all sections of both twines extending away from said knot; and for twines that have a lay direction, cambered sections that are present on such twine and that face outward from an outer surface of the improved trawl being oriented generally toward the front and back of the improved trawl.

14. The improved trawl of claim 13 wherein the first loop and of the second loop have opposite turn directions ("Z" and