CA2177564A1 - Vessel having a high-speed planing or semi-planing hull - Google Patents
Vessel having a high-speed planing or semi-planing hullInfo
- Publication number
- CA2177564A1 CA2177564A1 CA002177564A CA2177564A CA2177564A1 CA 2177564 A1 CA2177564 A1 CA 2177564A1 CA 002177564 A CA002177564 A CA 002177564A CA 2177564 A CA2177564 A CA 2177564A CA 2177564 A1 CA2177564 A1 CA 2177564A1
- Authority
- CA
- Canada
- Prior art keywords
- vessel
- cavity
- hull
- air
- planing
- Prior art date
- Legal status (The legal status 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 status listed.)
- Abandoned
Links
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 20
- 230000003068 static effect Effects 0.000 claims description 6
- 244000221110 common millet Species 0.000 claims description 4
- 230000001141 propulsive effect Effects 0.000 claims description 3
- 230000035939 shock Effects 0.000 description 4
- 238000012360 testing method Methods 0.000 description 3
- GRYSXUXXBDSYRT-WOUKDFQISA-N (2r,3r,4r,5r)-2-(hydroxymethyl)-4-methoxy-5-[6-(methylamino)purin-9-yl]oxolan-3-ol Chemical compound C1=NC=2C(NC)=NC=NC=2N1[C@@H]1O[C@H](CO)[C@@H](O)[C@H]1OC GRYSXUXXBDSYRT-WOUKDFQISA-N 0.000 description 2
- 101100523539 Mus musculus Raf1 gene Proteins 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
- B63B1/32—Other means for varying the inherent hydrodynamic characteristics of hulls
- B63B1/34—Other means for varying the inherent hydrodynamic characteristics of hulls by reducing surface friction
- B63B1/38—Other means for varying the inherent hydrodynamic characteristics of hulls by reducing surface friction using air bubbles or air layers gas filled volumes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T70/00—Maritime or waterways transport
- Y02T70/10—Measures concerning design or construction of watercraft hulls
Landscapes
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Ocean & Marine Engineering (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Filling Or Discharging Of Gas Storage Vessels (AREA)
- Other Liquid Machine Or Engine Such As Wave Power Use (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
- Structure Of Belt Conveyors (AREA)
- Mechanical Means For Catching Fish (AREA)
- Sealing Using Fluids, Sealing Without Contact, And Removal Of Oil (AREA)
Abstract
A vessel having high-speed planing or semi-planing hull comprising: (a) a first portion (12) located at the bow and configured to provide a forward planing portion; (b) a second portion (13) aft of the first portion comprising a shallow cavity (14) having a forward end defined by a step (15) extending across the hull at the forward end of the second part, a rib (16) located to each side of the hull for the length of the second portion; (c) a pressurised air source provided in the vessel and connected to the cavity (14) to deliver air under pressure to the cavity through an outlet (17) whereby the air is distributed substantially evenly into the cavity and in a manner which does not disturb the surface of the water below the cavity (14); and (d) a third portion aft of the cavity (14) providing a seal at the aft end of the cavity in the form of an aft profiled surface formed with one or more channels (20) extending from the cavity (14) to the stern to permit the controlled flow of air from the cavity (14) such that a substantial portion of the third portion has no contact with the air flowing from the cavity.
Description
Wo 95/14604 2 1 7 ~ 5 ~ 4 PCr/AUs4/00733 "VESSEB ~AVING A HIGH--SPEED PLANING OR SENI-PLANING HULL"
THIS INVE~TION relates to high speed marine craft hull forms of both mono hull and multi-hulled form.
The invention relates particularly to improving the llydLudy-lamic efficiency of high speed marine craft, principally to mono-hulled or multi-hulled vessels which would otherwise be of a planing or semiplaning nature, by the introduction of a very shallow but pressurised air cavity in the bottom of the craf t ' s rigid hull . The L~ t in overall lly~h~dy~lamic ~ ffiri~nr~y of ship hulls has been the subject of much research and the concept of introducing air beneath a ship ' s hull with the intention of improving it's llydLudy~lamic ~ff;rif-nl-y is not new. The non-i 5;h;nus side wall hovercraft (otherwise knowi. as a surface effect ship, SES) is a prime example of such an application, although there are many others. Other examples of such prior art comprise US3742888, US4393802, US1824313, ~S1389865, AU--A--33446/84, AU--A--87515/83, AU--A--44236/79, GB2112118, GB2060505, GBl311g35, JP3--243489, DE--A-3208884, DE-A-2831357, WO-A-85/00332 and EP-A-0088640.
In regard to that prior art however, the power requirement to maintain the air cavity at it ' 8 working pressure has been a relatively high proportion (typically 15% to 50%) of their main propulsion power requirements. Nany of these designs also have the disadvantage of requiring f lexible seals to ~-;nti~;n the air cavity in place. Another feature of these existing designs is the relatively large volume or depth of cavity employed which makes it ~l;ff;~nllt to maintain the design air pressure in disturbed sea conditions where air can rapidly leak from the cavity.
This ~; ff; C~ll ty is a contributing factor to the normally high ~ supply system pow--: requirement.
Wo 95/14604 PCTIAU94/00733 217~56~ - 2 -The invention relates to the ; ~ u" L of ~Iy-lLudyllamic ef f iciency of a mono or multi hulled high speed marine craft. This i8 brought about by supporting a significant proportion of the craft weight on pressurised air, in the f orm of a thin f ilm of air which is maintained under the bottom of the hull. This air film is maintained within the bounds of a shallow cavity integrated into the lower hull of the vessel. The arrangement reduces the resistance (both frictional and residuary resistance) to forward motion of the craft compared to an equivalent craft without the invention employed.
Accordingly the invention resides in a vessel having a high speed planing or semiplaning hull comprising;
( a ) 2 f irst portion located at the bow and conf igured to provide a forward planing portion;
(b) a second portion a~t of the first portion comprising a shallow cavity having a forward end defined by a step r~lrtr~ ; n~ across the hull at the forward end of the second portion and a rib located to each side of the hull for the length of the second portion;
(c) a pressurised air source being provided in the vessel and connected to the cavity to deliver air under pressure to the cavity through an outlet whereby the air is distributed substantially evenly into the cavity and in a manner which does not disturb the surface of the water below the cavity; and (d) a third portion aft of the cavity providing a seal at the aft end of the cavity and ~ormed with one or more ~h~nnf.l ~ extending from the cavity to the stern Wo 95/14604 2 1 7 ~ 5 G 4 PCr1AUs4100733 to permit the controlled loss of air from the cavity auch that a substantial portion of the third portion has no contact with the air flowing from the cavity.
According to a preferred feature of the invention the forward planing portion is formed with a central rib which extends to each side of the central longitudinal axis and which extends from a position in the region of or forward of the water line to the step or a position forward of the 6tep . The prof ile of the lower surf ace of the rib can be generally of corresponding profile to the hull to each side of the rib while the sides pre6ent a step in the profile of the hull. If desired, the depth of the step can vary along it6 length whereby it is at its maximum at an int~ te position alon~ its length. If desired the deadrise of the rib can vary along its length being at its minimum towards its aft end. In addition, the rib may t~rTni n~te forward of the step and in such a case the hull may be generally of constant profile between the aft end of the rib and the step . If desired the ~ ~wer edges of the rib may extend beyond the face of tne step. According to a preferred feature of the invention the rib is formed as a member supported from the hull which is capable of adjustment to vary the degree of protrusion of the rib from the hull. If desired, the rib is r~s; 1 i~ntly supported from the hull.
According to a pref erred f eature of the invention the forward planing portion i6 provided with a plurality of secondary ribs to each side of the central axis and which are configured and placed to control the water flow past the forward pl~ning portion such that the water flow is substantially axial.
According to a preferred feature, the substantial portion of the third portion is formed as one or more regions of positive deadri~e.
Wo 95114604 , PCr1~U94100733 2 1 7 7 ~ 6 4 4 According to a further preferred feature the third portion has negative deadrise such that the substantial portion of the third portion i6 located to either side.
According to a preferred feature the ribs extend for at least a portion of the third portion.
According to a preferred feature the face of the third portion is ;nrl ;n~d downwardly from the second portion to the stern. In addition, if desired the upper wall of the cavity is ;nrl;nP~ downwardly towards the stern.
According to a further preferred feature of the invention the substantial portion of the third portion is adapted to a~- '^te propulsive units.
According to a preferred feature o~ the invention, the second portion is formed with a plurality of longit---l;niql ly spaced shallow cavities each defined by a gtep PlrtPn~;ng transversely across the hull at its forward end and a rib located to each side of the hull, the pressurised air source being provided in the vessel and connected to the cavities to deliver air under pressure to each of the cavities through an outlet. If desired, the air source to each cavity can be; n~l~p~n~ nt of the other cavities and the air pressure maintained in the each cavity can vary f rom the air pressure in the other cavities or can be equal. In addition, the air pressure in the cavities can be varied In addition, if desired the forward cavities communicate with the adjacent aftmost cavity through passageways. If desired the pasE~ y~ may be A~sor; ~tPd with means to regulate the degree of ~ ; cAtion where the regulation i8 governed by aspects of hull motion such as hull speed, pitch and roll.
Wo 95114604 2 1 7 ~ 5 6 ~ PCT/A1~94/00733 A benefit of the invention has been found to comprise re~ c~ion in resistance of up to 35~ with a total air supply power requirement of less than 5~ of the required design propulsive power requirement. This means that the air supply system can be very small relative to the main propulsion r~eh;n~ry of the vessel.
Although the invention is applicable to what would otherwise be Vee or Round bottom high speed craft, the introduction of the invention Pi~n;~;cAntly changes the underwater shape of the craft such that these conventional descriptions would no longer apply. The craft with the invention would be an essentially flat buL ~ vessel with small side ribs and a very low deadrise underwater Vee bow.
It is the nature of these 8; ~n i f i ~Ant changes and the effects that they have, which provides the high gain in overall ef f j ~iency which makes the present invention 80 different from the prior art. As a result, the hull is capable of a higher speed than is available in equivalent craft without an increase in power which would be expected with equivalent cr~ft of a conventional form.
According to a preferred feature the sides of the cavlty are sealed by straight or swept side ribs. The inner edges of the side ribs and the aft edges of the forward planing step are shaped to promote clean water separation and minimum turbulence.
According to a preferred feature the upper surface of the cavity top, which forms the upper boundary of the air cavity can be angled down, from its forward most end towards its aft end and the third portion is also angled down with an increased inclination. As a result, the third portion at least, by virtue of its increased angle of inclination compared to the second portion is contacted by Wo 95/14604 PCr1AU94100733 217~56~ - 6 -the water to create a seal at the aft end of the cavity, which is profiled to have 1lydLu~iyllamic ~ffir;.on~y and to control the loss of air from the cavity. The third portion of the hull is formed with one or more ~hAnn~l R to allow the air to escape to the stern of the hull through the one or more ahAnn~l R formed in the third portion. The presence of the ~hAnnel ~ serves to control and minimise the air :Elow rate from the cavities and substantially reduces the cavity air ref ill rate in rough sea conditions . In addition, the rhAnnf~l R ensure that the L- i nrl~r of the third portion is substantially free from any contact with the air from the cavity. This enables propulsion units to be located at the l~ ; nrl~r of the third portion whereby their pelLuL111a11ce will not be inhibited by the air flowing f rom the cavity .
According to a pref erred f e~ture of the invention at least A rear part of the third portion is displacable vertically with respect to the hull to vary the inclination of the third portion. In this regard, the whole of the surface of the rear part of the third portion between the side ribs can be movable or it can be subdivided into segments located between the ~hAnnf~l R . The movable rear part can have or can provide one or more channels positioned in uulle~l~u~ nce with the one or more ~h~nn~l ~ in the third portion. Support ~or the movable rear part may be of a resilient form to provide for the at least partial absorption of shocks and the like, The movable rear part serves to enhance stability of vertical ~,~ t and to reduce excessive 1OA~1;n~R on the stern portion of the ves sel .
A vessel designed in accordance with the above has a distin~-iRhins feature that the total volume of the air cavity is small compared to the static displaced volume of the hull. Typically the ratio of total air cavity volume to total static displaced volume is from 0 . 05 to 0 . 2 .
Wo 95114604 2 1 7 7 ~ 6 ~ PCTI~U94/00733 -An example of the vessel designed in accordance with the above has a distin~l;~h;ng feature that the power required to supply the air film is only a small percentage of the power required to propel the craft. Whilst the design flow rate of the air supply is related to the sealinq arrAn ~, -t.s of the particular cavity design, the design f low rate of the air supply is such that when multiplied by the design air pressure and divided by the efficiency of the pressurised air supply system, the resulting power is no greater than 5~ of the Delivered Power required to propel the craft at its design speed in its design condition ~where the Delivered Power is the power required to be delivered to the propulsion device to propel the craf t at a certain speed ) .
A vessel designed in accordance with the above has a distinguishing feature that the pressure of the air in the cavity is such that this pressure multiplied by the non-wetted platform area of the cavity is equal to a ~ir~n;f;r~nt proportion of the design weight of the craft which typically is of the order of 30~ to 60~ of the design weight of the craft.
According to a preferred feature the forward end of the upper surface of the cavity is formed with a transverse second step which reduces the depth of the cavity towards the forward end, said air being delivered to the cavity across the end face of the step and from a plurality of op~n;n~ on the lower face of the step. Preferably the majority of the air flow is from across the end face of the step. According to a preferred feature the second step is formed by a plate member mounted transversely across the cavity. I'he entry of air into the cavity is such that the surface of the water below the cavity is not ,l~f~ ' by the air f low f rom the second step .
Wo gs/l4604 ~ PCrlAU94/00733 f~l77~iG~ - 8 - ~
In an _'i t of the invention, the pressurized air is introduced from behind f a flat plate mounted horizontally within the forward end of the cavity. The plate is provided with openings in its lower face to allow some air into the forward portion of the cavity. The air is rrnt~;nf~d in the cavity by planing Yectors of the hull at the forward end which terminate in a straight or swept planing step. This step which forms the forward end of the cavity, is substantially forward in the craft, being a distance of 396 to 3596 of the static waterline length of the craft aft of the forward perp~nA;r~ r. The lower portion of this forward planing sector of the hull is made in the form of low deadrise Vee section.
If desired the plate can be angled and extended aft to a distance no more that half the length of the air cavity and provided with a sharp trailing edge to ensure clean separation of any water that should impinge on it. The deadrise angle of this plnte may be equal to or less than that at the forward planing step. This feature can lead to i ~ uv~:d perfrr~~nrr of the air cavity in disturbed sea conditions .
Furfh~ if desired, the plate can be constructed in an angled, stepped form all the way to the stern, with the deadrise angle of each step being equal to or less than the one immediately in front of it, the forward most step having a deadrise angle equal to or less than that of the forward planing step. This feature can lead to i uve:d pe.L ~ ~- - re in calm and disturbed sea conditions particularly for high length to benm ratio vessels.
Accordins to a pref erred f eature of the invention the rh~nn~ may be provided with regulation means which are able to regulate air flow from the cavity. The regulation means may comprise vanes of the like which can be moved to WO 95/14604 ~ 1 7 7 ~ ~ ~ PC r/AUs4/00733 vary the cross-sectional area of the channels. The regulation of air flow can serve to provide a control for the trim~ and heel of the vessel.
According to a f eature of an ; ).~ of the invention, the ribs are of substantially constant width throughout their length . Alternatively in another : ~ i L the ribs may decrease in width rearwardly of the step.
According to another pref erred f eature of the invention the transverse distance between the chines of the hull in the region of the step is at most equal to the transverse distance between the chineg of the hull Ami~lRhiE.-2.
The invention will be more fully understood in the light of the following description of several specific embodiments.
The description is made with reference to the ~ nying drawings of which:-Figure 1 is an underneath plan view of a hull according to the f irst F~ gure 2 is a sectional elevation of a hull according to the first ~ L;
Figures 3A, 3s and 3C are cross-sectional views of the hull of Figure 2 at lines A-A, B-B, C-C respectively;
Figures 4A, 4B, 4C, 4D, 4E, 4F, 4G and 4H illustrate a variety of profiles for the . ~~i L along line D-D
of Figure 2 and of Figure 10;
Figures 5A and Ss illustrate the relationship between the forward cavity depth and d~th of the planir,g step area of the forward and rearward portion of the cavity respectively;
~U~IllU~ SHEET (Rulc 2~j Wo 95/14604 PCTIAU94/00733 2~ 64 - lo -Figure 6 is an lln~ rn~ath plan view of a second ~ _-ir L having an r~Yfr n~ plate;
Figure 7 is an underneath plan view of a third ~ ` '; L having a set of extended plates;
Figure 8 grArhir~lly illustrates the results from model tests of an example of the first embodiment where resistance trim, heave and the pressurised air pressure and f low rate are all shown as a function of ship forward speed;
Figure 9 is an underneath ~lan view of a hull according to the f ourth ~ L;
Figure 10 is a sectional elevation of a hull according to the fourth: ` -ii L;
Figure llA, llB, llC are cross-sec~;on 1l views of the hull of Figure 10 at lines A-A, B-B, C-C respectively;
Figure 12 is a side elevation of a form of the forward portion of a hull which can be utilised in each o~ the ~"ho~; Ls; and Figures 13A, 13B, 13C, 13D, 13E, 13F and 13G are cross sections along lines A-A, B-B, C-C, D-D, E-E, F-F, G-G
of the f orward portion shown at Figure 12 .
Figure 14 is a schematic view of the stern of a vessel according to another . - ' i - L .
In all of the drawings the abbreviations CL mean Centreline and SWL means Static Water ~ine.
~ WQ 95~14604 21 7 7 5 ~ ~ PCT/AU94/00733 rrhe f irst ~ of the invention as shown at Figures 1, 2 and 3 comprises a high speed planing hull 11 which i8 formed with a forward portion 12 which has a generally conventional planning cnnf i ~lration except it incorporates a low deadrise planing section in its lower portion; and a second portion 13 which A' I~lAt~ the cavity 14. The forward portion 12 i8 6eparated from the second portion 13 by a step 15 which defines the forward boundary of the cavity 14. The sides of the cavity 14 are defined by a narrow ribs 16 to each side of the hull of equal width or gradually becoming wider as they extend from the stern to the forward end of the cavity and forming lateral extensions of the forward portion. The wetted area of the hull at design co~ditions is shown crosshatched at Figure 1.
Figures 3A, 3B, 3C provide an indication of the cross-sectional t~nnf i g~lration of the hull on the lines A-A, B-B, C-C of Figure 2.
A8 shown in Figures 3B and 3C the upper surface of the cavity 14 is substantially planar and as shown at Figures 2 and 3s and 3C the upper surface is in~l in~d downwardly towards the stern of the hull . The ribs which f orm the sides of the cavity in the central portion extend to the third portion aft of the cavity and can have a low positive deadrise at the inner side of the rib. In addition, the mid-portion of the third portion can be f ormed to have a portion of positive deadrise to each side of the central axis .
As a result of the ~nn Fi ~uration of the cavity and the third portion of the hull, the air in the cavity is maintained in the cavity and any 1088 of air i8 generally controlled. Furthermore, the loss of air from the rear of the cavity past the third portion is effected through ~-hAnnf.1~ 20 formed between the cavity and the stern a~d 4,30g dS -- 12 -- PCrlAU94100733 Figures 4A - 4H illustrate a variety of profiles available for the third portion along line D-D of Figure 2 where the third portion i6 formed of ~hAnn~l ~ 20 which extend between the cavity and the stern. The presence o the channels serves to control the 1055 of air from the cavity and ensures that a substantial portion of the third portion is not in contact with air or air bubble5 flowing from the cavity. This enables the location of propulsion units such a5 propellors or the like in the 5ub5tantial portion whereby they are not af f ected by the air f lowing f rom the cavity. The rhAnn~ can if desired incorporAte a flow control in the form of vanes which can be used to vary the cross-sectional area of the rhAnnRl ~ . In 80 doing some control can be provided for the trim and heel of the ves sel .
The cavity 14 is pressuri6ed from a pressure source (not shown) a~ '~ted within the vessel which is connected to an outlet 17 provided in the upper wall Qf the cavity 14 towards its forward end. The outlet is associated with a plate 18 which extends across the cavity in the region below the outlet 17 int~ te of the depth of the cavity. Air delivered from the outlet 17 i8 delivered into the cavity from the rear edge of the plate 18.
Figures 5A and 5s illustrate the proportions between the depth H1 of the f orward portion and rear portion of the air cavity respectively compared to the depth H2 of the planing step area of the rib portion 16. The relat;~n~hip between these values in the forward portion of the cavity area is such that the depth H1 of the air cavity in that region is 10% to 40% greater than the depth H2 of the planing step area of the rib . Pref erably in the f orward region of the cavity the ratio of H1 and H2 is generally less than O . 5 and can incre~se in the aft portion of the c~vity to be more than O . 5 .
~VI~ U~ SEIEET (Rule 26) W0 95/14604 `2 L 7 7 ~ 6 ~ PCTI~Ug4100733 The rela~;nn~hir between the ~orward portion 12 is 3uch that the distance L2 between the step 15 ~iPfin;n~ the forward end of the air cavity and the forward end of the waterline of the vessel 19 as compared to the waterline length Ll of the vessel is of the order of 0 . 05 and 0 . 40 .
If desired the plate 18 may be extended such that it extends for a distance equal to up to half of the length of the air cavity as shown at Figure 6.
In addition, according to a third em})odiment as shown at Figure 7 a plurality of air outlets may be provided in the upper wall of the air cavity 14 and each may be associated with a ventilating plate 18 at a spaced intervals along the cavity .
Figure 8 illustrates the results of testing an example of the ~ ; L shown at Figures 1, 2 and 3. The test model was representative of a vessel of a length of 74 metres and a displ~ L of 700 tonnes. The l~::yr ese:l-Lations provide an indication of the resistance values, degree of trim, the degree of heave, the variation in air cavity pressure and variation of air supply or f low rate . In Figure 8A the solid line indicates the resistance curve of a vessel of corresponding configuration but not in.u~oLcLting a cavity while the broken line illustrates the relatinn~hir of resistance and hull speed of the example of the L .
Similarly, in relation to Figure 8B that figure illustrates by the solid line the angle of trim of an ordinary vessel of corresponding conf iguration to the example while the broken line illustrates the angle of trim of the example of the hull according to the ~ L.
WO 95/14604 ~ PCr/AU94/00733 ~7~6~ - 14 -Similarly Figure 8C illustrates the variation in heave for the vessel without the invention (the solid line) as compared with the vessel with the invention (the broken line ) .
Figures 8D and 8E illustrate the variation in air cavity pressure and air supply flow rate in a hull inuuLyoLaLing the invention as a function of hull speed.
The fourth ~ t of the invention as shown at Figures 9, 10 and 11 has a high speed planing hull 111 which is formed with a forward portion 112 which has a generally conventional ~r~nf; gl~ration except that it in~ul~ola~es a low deadrise planing section in its lower portion and a second portion 113 which inuul~ulAtes a plurality of longit~ inAl ly spaced cavities 114. The forwardmost cavity 114 is separated from the forward portion 112 by a first step 115 which defines the forward boundary of the forwardmost cavity 114. In addition, each of the subsequent cavities is formed with a forwardmost step 115 which each represents the termination of the upper surf ace of the adjacent ~ùlw~ cavity 114. In Figure 9 the wetted area of the hull under design condition is shown as crosshatched .
Figures llA, s and C provide an indication of the cross-sectional c~nfigllration of the hull on the lines A-A, B--B and C-C of Figure lO.
The side of each cavity is defined by a narrow ribs 116 to each side of the hull of equal with or gradually becoming wider f rom the stern to the f orward end of the cavity and which in each case forms lateral and longitudinal extensions of the portion of the hull forward of the respective step.
~ Wo gSl14604 2 ~ 7 7 5 ~ ~ PCT/AU94l00733 -- 15 -- ~ -The upper walls of each cavity 114 are 5ubstantially planar but as shown in Figure g are inrl inPd downwardly towards the stern of the hull where~y the ribs 116 of the respective cavity terminate on the upper wall of that cavity intersecting the plane of the ribs. This occurs immediately prior the transverse axes of the step of the following cavity. The cavities 114 are interconnected by second rhAnnpl R 125 to enable air to flow between the cavities. If desired each second channel may be provided with regulating vanes or like elements which can be adjusted to control the degree of flow through the second ~hAnnRl ~ 114. The adjustment of the regulating vanes or the Like can be effected manually or automatically according to the hull of the vessel and for the degree of roll of the vessel.
The ribs which form the sides of the cavity in the central portion can extend into the third portion aft of the cavity and can have a low positive deadrise at the inner side. In addition, the mid-portion of the third portion is formed to have a positive deadrise to each side of the central axis.
A~ a result of the t~nnf i ~lration of the cavity and the th ~ rd portion of the hull, the air in the cavity is maintained in the cavity and any 10~8 of air is generally controlled. Fur~h~ L~:~ the 1088 of air from the rear of the cavity past the third portion is permitted in a controlled manner through channels 125 which are between the cavity and the 6tern.
The relafinnRhi~ between the forward portion 112 is such that the ratio of distance L2 between the f orward perpendicular of the fuLw~L' ~t extent of the waterline which i6 marked FP and the ~olwc~l, ,.,L cavity step 115 to the waterline length of the vessel Ll is between 0 . 03 and 0.35 .
Wo 95114604 ~ PCTl~1~94l00733 ~
21~564 - 16 -Each cavity 114 i8 pressurised from a pressure source (no~
shown) P~ dated within the vessel which i6 connected to an outlet 117 provided in the upper wall of each cavity 114 towards its forward end. Each outlet 117 i8 asBoCiated with a plate 118 which extends Rcross the cavity in the region below the outlet 117 int~ te of the depth of the cavity. Air delivered from the outlet 117 is delivered into the cavity 114 across the rear edge of the plate 118.
If desired the delivery of air to each of the outlets 117 may be effected from a common pressure source.
Alternatively the air may be delivered to each cavity ~rom an ; n~ p~ntl~nt pressure source. This can improve the p~=l r~ ..r~ of the embodiment in rough sea conditions and in certain situations enables the air being delivered to each cavity to vary, which serves to optimise control of the motion and attitude of the vessel according to sea conditions by the varying the cavity air volume in each cavity. In addition, the pressure maintained in each cavity may vary from the air pres8ure in adjacent cavities .
As shown at Figures 12 and 13 the forward planing portion 12 of the hull of each of the e ' ';- I s can be formed to have a central rib 26, which extends to each side of the central axis. The rib has a cross-sectional profile which is an extension of the profile of the hull to each side of the rib, at ~ny particular location along the rib however the rib serves to project its profile outwardly from the profile of the L~ ; nrl~r of the hull . In addition, the rib extends from a position forward of the water line B-3 to the step 15.
The function of the central rib is to shape the surface of the water in the region of the cavity and which f orms the lower wall of the cavity such that the there will be no ~ ~0 95/14604 2 ~ 7 7 5 6 4 Pcr/AUg4/00733 collapse of that surface and whereby the integrity of the cavity is maintained. The rib reduces in deadrise rearwardly along the hull. If desired the rib can terminate before the step in which case the profile of the hull between the central rib and step remains substantially constant .
In addition, if desired the rib can be formed as a support member which is movable inwardly and outwardly with respect to the hull according to the operating characteristics and water conditions. In addition or alternatively the member may be resiliently supported from the hull to provide some shock absorbing preparation.
In addition, the forward planing portion may be formed with (not shown) a plurality of secondary ribs in the form of f ins or thin chines to each side of the central rib to further control the flow of water past the forward most portion to the second portion.
One ' ined benefit of these features is to reduce the vertical forces or heave exerted on the vessel in rough sea conditions .
If desired the plate of each of the embodiments may be dispensed with and the upper surface of the cavity can be formed with stepped cnnfi~ration where a~r is delivered across the rear face of the step. The stepped upper wall of the c~vity in.c~ LaLes the feature of the plate of previous ' ~ Ls as an integral feature of the hull.
of course appropriate means must be provided to equalise the distribution of air across the rear face of the step.
i Air is delivered into the cavity in each of the ~ i r ts at a pressure such that the vertical force applied to the interior of the cavity is roughly equal to 309~ to 6096 of WO 95114604 PCTIAU94/00733 ~
21~5~ - 18 -the design weight oi~ the vessel. In addition, the total cavity volume of the cavity iB of the order of 5% to 20% of the displaced volume of the vessel.
According to ~mother embodiment as shown at Figure 14 the surface of the third portion is formed to be displacable.
The 6urf~ce of the third portion is formed by several more segments 230 which are pivotally supported ~rom their forward edge to be pivotable downwardly to vary the ;ncl in.q1-;nn of the surface of the third portion. ~he segments 230 are spaced to provide one or more rh~nnel ,:
which are in correspnnri~nrp with one or more channels 220 in the third portion. The 8upport for the segments (shown schematically in Figure 14 at X) i5 resilient to provide some shock ~hgQrhin~ properties. ~he rP~il ir~ntly displacable segment serve to provide some stability against vertical ~, L and reduce shock loadings on the third portion in rough sea8.
It should be appreciated that the scope of the present invention need not be limited to the particular scope of the , ~ - 1; L described above. In particular the invention has application to multi hulled vessels where each hull is fQrmed with a cavity of the form described.
THIS INVE~TION relates to high speed marine craft hull forms of both mono hull and multi-hulled form.
The invention relates particularly to improving the llydLudy-lamic efficiency of high speed marine craft, principally to mono-hulled or multi-hulled vessels which would otherwise be of a planing or semiplaning nature, by the introduction of a very shallow but pressurised air cavity in the bottom of the craf t ' s rigid hull . The L~ t in overall lly~h~dy~lamic ~ ffiri~nr~y of ship hulls has been the subject of much research and the concept of introducing air beneath a ship ' s hull with the intention of improving it's llydLudy~lamic ~ff;rif-nl-y is not new. The non-i 5;h;nus side wall hovercraft (otherwise knowi. as a surface effect ship, SES) is a prime example of such an application, although there are many others. Other examples of such prior art comprise US3742888, US4393802, US1824313, ~S1389865, AU--A--33446/84, AU--A--87515/83, AU--A--44236/79, GB2112118, GB2060505, GBl311g35, JP3--243489, DE--A-3208884, DE-A-2831357, WO-A-85/00332 and EP-A-0088640.
In regard to that prior art however, the power requirement to maintain the air cavity at it ' 8 working pressure has been a relatively high proportion (typically 15% to 50%) of their main propulsion power requirements. Nany of these designs also have the disadvantage of requiring f lexible seals to ~-;nti~;n the air cavity in place. Another feature of these existing designs is the relatively large volume or depth of cavity employed which makes it ~l;ff;~nllt to maintain the design air pressure in disturbed sea conditions where air can rapidly leak from the cavity.
This ~; ff; C~ll ty is a contributing factor to the normally high ~ supply system pow--: requirement.
Wo 95/14604 PCTIAU94/00733 217~56~ - 2 -The invention relates to the ; ~ u" L of ~Iy-lLudyllamic ef f iciency of a mono or multi hulled high speed marine craft. This i8 brought about by supporting a significant proportion of the craft weight on pressurised air, in the f orm of a thin f ilm of air which is maintained under the bottom of the hull. This air film is maintained within the bounds of a shallow cavity integrated into the lower hull of the vessel. The arrangement reduces the resistance (both frictional and residuary resistance) to forward motion of the craft compared to an equivalent craft without the invention employed.
Accordingly the invention resides in a vessel having a high speed planing or semiplaning hull comprising;
( a ) 2 f irst portion located at the bow and conf igured to provide a forward planing portion;
(b) a second portion a~t of the first portion comprising a shallow cavity having a forward end defined by a step r~lrtr~ ; n~ across the hull at the forward end of the second portion and a rib located to each side of the hull for the length of the second portion;
(c) a pressurised air source being provided in the vessel and connected to the cavity to deliver air under pressure to the cavity through an outlet whereby the air is distributed substantially evenly into the cavity and in a manner which does not disturb the surface of the water below the cavity; and (d) a third portion aft of the cavity providing a seal at the aft end of the cavity and ~ormed with one or more ~h~nnf.l ~ extending from the cavity to the stern Wo 95/14604 2 1 7 ~ 5 G 4 PCr1AUs4100733 to permit the controlled loss of air from the cavity auch that a substantial portion of the third portion has no contact with the air flowing from the cavity.
According to a preferred feature of the invention the forward planing portion is formed with a central rib which extends to each side of the central longitudinal axis and which extends from a position in the region of or forward of the water line to the step or a position forward of the 6tep . The prof ile of the lower surf ace of the rib can be generally of corresponding profile to the hull to each side of the rib while the sides pre6ent a step in the profile of the hull. If desired, the depth of the step can vary along it6 length whereby it is at its maximum at an int~ te position alon~ its length. If desired the deadrise of the rib can vary along its length being at its minimum towards its aft end. In addition, the rib may t~rTni n~te forward of the step and in such a case the hull may be generally of constant profile between the aft end of the rib and the step . If desired the ~ ~wer edges of the rib may extend beyond the face of tne step. According to a preferred feature of the invention the rib is formed as a member supported from the hull which is capable of adjustment to vary the degree of protrusion of the rib from the hull. If desired, the rib is r~s; 1 i~ntly supported from the hull.
According to a pref erred f eature of the invention the forward planing portion i6 provided with a plurality of secondary ribs to each side of the central axis and which are configured and placed to control the water flow past the forward pl~ning portion such that the water flow is substantially axial.
According to a preferred feature, the substantial portion of the third portion is formed as one or more regions of positive deadri~e.
Wo 95114604 , PCr1~U94100733 2 1 7 7 ~ 6 4 4 According to a further preferred feature the third portion has negative deadrise such that the substantial portion of the third portion i6 located to either side.
According to a preferred feature the ribs extend for at least a portion of the third portion.
According to a preferred feature the face of the third portion is ;nrl ;n~d downwardly from the second portion to the stern. In addition, if desired the upper wall of the cavity is ;nrl;nP~ downwardly towards the stern.
According to a further preferred feature of the invention the substantial portion of the third portion is adapted to a~- '^te propulsive units.
According to a preferred feature o~ the invention, the second portion is formed with a plurality of longit---l;niql ly spaced shallow cavities each defined by a gtep PlrtPn~;ng transversely across the hull at its forward end and a rib located to each side of the hull, the pressurised air source being provided in the vessel and connected to the cavities to deliver air under pressure to each of the cavities through an outlet. If desired, the air source to each cavity can be; n~l~p~n~ nt of the other cavities and the air pressure maintained in the each cavity can vary f rom the air pressure in the other cavities or can be equal. In addition, the air pressure in the cavities can be varied In addition, if desired the forward cavities communicate with the adjacent aftmost cavity through passageways. If desired the pasE~ y~ may be A~sor; ~tPd with means to regulate the degree of ~ ; cAtion where the regulation i8 governed by aspects of hull motion such as hull speed, pitch and roll.
Wo 95114604 2 1 7 ~ 5 6 ~ PCT/A1~94/00733 A benefit of the invention has been found to comprise re~ c~ion in resistance of up to 35~ with a total air supply power requirement of less than 5~ of the required design propulsive power requirement. This means that the air supply system can be very small relative to the main propulsion r~eh;n~ry of the vessel.
Although the invention is applicable to what would otherwise be Vee or Round bottom high speed craft, the introduction of the invention Pi~n;~;cAntly changes the underwater shape of the craft such that these conventional descriptions would no longer apply. The craft with the invention would be an essentially flat buL ~ vessel with small side ribs and a very low deadrise underwater Vee bow.
It is the nature of these 8; ~n i f i ~Ant changes and the effects that they have, which provides the high gain in overall ef f j ~iency which makes the present invention 80 different from the prior art. As a result, the hull is capable of a higher speed than is available in equivalent craft without an increase in power which would be expected with equivalent cr~ft of a conventional form.
According to a preferred feature the sides of the cavlty are sealed by straight or swept side ribs. The inner edges of the side ribs and the aft edges of the forward planing step are shaped to promote clean water separation and minimum turbulence.
According to a preferred feature the upper surface of the cavity top, which forms the upper boundary of the air cavity can be angled down, from its forward most end towards its aft end and the third portion is also angled down with an increased inclination. As a result, the third portion at least, by virtue of its increased angle of inclination compared to the second portion is contacted by Wo 95/14604 PCr1AU94100733 217~56~ - 6 -the water to create a seal at the aft end of the cavity, which is profiled to have 1lydLu~iyllamic ~ffir;.on~y and to control the loss of air from the cavity. The third portion of the hull is formed with one or more ~hAnn~l R to allow the air to escape to the stern of the hull through the one or more ahAnn~l R formed in the third portion. The presence of the ~hAnnel ~ serves to control and minimise the air :Elow rate from the cavities and substantially reduces the cavity air ref ill rate in rough sea conditions . In addition, the rhAnnf~l R ensure that the L- i nrl~r of the third portion is substantially free from any contact with the air from the cavity. This enables propulsion units to be located at the l~ ; nrl~r of the third portion whereby their pelLuL111a11ce will not be inhibited by the air flowing f rom the cavity .
According to a pref erred f e~ture of the invention at least A rear part of the third portion is displacable vertically with respect to the hull to vary the inclination of the third portion. In this regard, the whole of the surface of the rear part of the third portion between the side ribs can be movable or it can be subdivided into segments located between the ~hAnnf~l R . The movable rear part can have or can provide one or more channels positioned in uulle~l~u~ nce with the one or more ~h~nn~l ~ in the third portion. Support ~or the movable rear part may be of a resilient form to provide for the at least partial absorption of shocks and the like, The movable rear part serves to enhance stability of vertical ~,~ t and to reduce excessive 1OA~1;n~R on the stern portion of the ves sel .
A vessel designed in accordance with the above has a distin~-iRhins feature that the total volume of the air cavity is small compared to the static displaced volume of the hull. Typically the ratio of total air cavity volume to total static displaced volume is from 0 . 05 to 0 . 2 .
Wo 95114604 2 1 7 7 ~ 6 ~ PCTI~U94/00733 -An example of the vessel designed in accordance with the above has a distin~l;~h;ng feature that the power required to supply the air film is only a small percentage of the power required to propel the craft. Whilst the design flow rate of the air supply is related to the sealinq arrAn ~, -t.s of the particular cavity design, the design f low rate of the air supply is such that when multiplied by the design air pressure and divided by the efficiency of the pressurised air supply system, the resulting power is no greater than 5~ of the Delivered Power required to propel the craft at its design speed in its design condition ~where the Delivered Power is the power required to be delivered to the propulsion device to propel the craf t at a certain speed ) .
A vessel designed in accordance with the above has a distinguishing feature that the pressure of the air in the cavity is such that this pressure multiplied by the non-wetted platform area of the cavity is equal to a ~ir~n;f;r~nt proportion of the design weight of the craft which typically is of the order of 30~ to 60~ of the design weight of the craft.
According to a preferred feature the forward end of the upper surface of the cavity is formed with a transverse second step which reduces the depth of the cavity towards the forward end, said air being delivered to the cavity across the end face of the step and from a plurality of op~n;n~ on the lower face of the step. Preferably the majority of the air flow is from across the end face of the step. According to a preferred feature the second step is formed by a plate member mounted transversely across the cavity. I'he entry of air into the cavity is such that the surface of the water below the cavity is not ,l~f~ ' by the air f low f rom the second step .
Wo gs/l4604 ~ PCrlAU94/00733 f~l77~iG~ - 8 - ~
In an _'i t of the invention, the pressurized air is introduced from behind f a flat plate mounted horizontally within the forward end of the cavity. The plate is provided with openings in its lower face to allow some air into the forward portion of the cavity. The air is rrnt~;nf~d in the cavity by planing Yectors of the hull at the forward end which terminate in a straight or swept planing step. This step which forms the forward end of the cavity, is substantially forward in the craft, being a distance of 396 to 3596 of the static waterline length of the craft aft of the forward perp~nA;r~ r. The lower portion of this forward planing sector of the hull is made in the form of low deadrise Vee section.
If desired the plate can be angled and extended aft to a distance no more that half the length of the air cavity and provided with a sharp trailing edge to ensure clean separation of any water that should impinge on it. The deadrise angle of this plnte may be equal to or less than that at the forward planing step. This feature can lead to i ~ uv~:d perfrr~~nrr of the air cavity in disturbed sea conditions .
Furfh~ if desired, the plate can be constructed in an angled, stepped form all the way to the stern, with the deadrise angle of each step being equal to or less than the one immediately in front of it, the forward most step having a deadrise angle equal to or less than that of the forward planing step. This feature can lead to i uve:d pe.L ~ ~- - re in calm and disturbed sea conditions particularly for high length to benm ratio vessels.
Accordins to a pref erred f eature of the invention the rh~nn~ may be provided with regulation means which are able to regulate air flow from the cavity. The regulation means may comprise vanes of the like which can be moved to WO 95/14604 ~ 1 7 7 ~ ~ ~ PC r/AUs4/00733 vary the cross-sectional area of the channels. The regulation of air flow can serve to provide a control for the trim~ and heel of the vessel.
According to a f eature of an ; ).~ of the invention, the ribs are of substantially constant width throughout their length . Alternatively in another : ~ i L the ribs may decrease in width rearwardly of the step.
According to another pref erred f eature of the invention the transverse distance between the chines of the hull in the region of the step is at most equal to the transverse distance between the chineg of the hull Ami~lRhiE.-2.
The invention will be more fully understood in the light of the following description of several specific embodiments.
The description is made with reference to the ~ nying drawings of which:-Figure 1 is an underneath plan view of a hull according to the f irst F~ gure 2 is a sectional elevation of a hull according to the first ~ L;
Figures 3A, 3s and 3C are cross-sectional views of the hull of Figure 2 at lines A-A, B-B, C-C respectively;
Figures 4A, 4B, 4C, 4D, 4E, 4F, 4G and 4H illustrate a variety of profiles for the . ~~i L along line D-D
of Figure 2 and of Figure 10;
Figures 5A and Ss illustrate the relationship between the forward cavity depth and d~th of the planir,g step area of the forward and rearward portion of the cavity respectively;
~U~IllU~ SHEET (Rulc 2~j Wo 95/14604 PCTIAU94/00733 2~ 64 - lo -Figure 6 is an lln~ rn~ath plan view of a second ~ _-ir L having an r~Yfr n~ plate;
Figure 7 is an underneath plan view of a third ~ ` '; L having a set of extended plates;
Figure 8 grArhir~lly illustrates the results from model tests of an example of the first embodiment where resistance trim, heave and the pressurised air pressure and f low rate are all shown as a function of ship forward speed;
Figure 9 is an underneath ~lan view of a hull according to the f ourth ~ L;
Figure 10 is a sectional elevation of a hull according to the fourth: ` -ii L;
Figure llA, llB, llC are cross-sec~;on 1l views of the hull of Figure 10 at lines A-A, B-B, C-C respectively;
Figure 12 is a side elevation of a form of the forward portion of a hull which can be utilised in each o~ the ~"ho~; Ls; and Figures 13A, 13B, 13C, 13D, 13E, 13F and 13G are cross sections along lines A-A, B-B, C-C, D-D, E-E, F-F, G-G
of the f orward portion shown at Figure 12 .
Figure 14 is a schematic view of the stern of a vessel according to another . - ' i - L .
In all of the drawings the abbreviations CL mean Centreline and SWL means Static Water ~ine.
~ WQ 95~14604 21 7 7 5 ~ ~ PCT/AU94/00733 rrhe f irst ~ of the invention as shown at Figures 1, 2 and 3 comprises a high speed planing hull 11 which i8 formed with a forward portion 12 which has a generally conventional planning cnnf i ~lration except it incorporates a low deadrise planing section in its lower portion; and a second portion 13 which A' I~lAt~ the cavity 14. The forward portion 12 i8 6eparated from the second portion 13 by a step 15 which defines the forward boundary of the cavity 14. The sides of the cavity 14 are defined by a narrow ribs 16 to each side of the hull of equal width or gradually becoming wider as they extend from the stern to the forward end of the cavity and forming lateral extensions of the forward portion. The wetted area of the hull at design co~ditions is shown crosshatched at Figure 1.
Figures 3A, 3B, 3C provide an indication of the cross-sectional t~nnf i g~lration of the hull on the lines A-A, B-B, C-C of Figure 2.
A8 shown in Figures 3B and 3C the upper surface of the cavity 14 is substantially planar and as shown at Figures 2 and 3s and 3C the upper surface is in~l in~d downwardly towards the stern of the hull . The ribs which f orm the sides of the cavity in the central portion extend to the third portion aft of the cavity and can have a low positive deadrise at the inner side of the rib. In addition, the mid-portion of the third portion can be f ormed to have a portion of positive deadrise to each side of the central axis .
As a result of the ~nn Fi ~uration of the cavity and the third portion of the hull, the air in the cavity is maintained in the cavity and any 1088 of air i8 generally controlled. Furthermore, the loss of air from the rear of the cavity past the third portion is effected through ~-hAnnf.1~ 20 formed between the cavity and the stern a~d 4,30g dS -- 12 -- PCrlAU94100733 Figures 4A - 4H illustrate a variety of profiles available for the third portion along line D-D of Figure 2 where the third portion i6 formed of ~hAnn~l ~ 20 which extend between the cavity and the stern. The presence o the channels serves to control the 1055 of air from the cavity and ensures that a substantial portion of the third portion is not in contact with air or air bubble5 flowing from the cavity. This enables the location of propulsion units such a5 propellors or the like in the 5ub5tantial portion whereby they are not af f ected by the air f lowing f rom the cavity. The rhAnn~ can if desired incorporAte a flow control in the form of vanes which can be used to vary the cross-sectional area of the rhAnnRl ~ . In 80 doing some control can be provided for the trim and heel of the ves sel .
The cavity 14 is pressuri6ed from a pressure source (not shown) a~ '~ted within the vessel which is connected to an outlet 17 provided in the upper wall Qf the cavity 14 towards its forward end. The outlet is associated with a plate 18 which extends across the cavity in the region below the outlet 17 int~ te of the depth of the cavity. Air delivered from the outlet 17 i8 delivered into the cavity from the rear edge of the plate 18.
Figures 5A and 5s illustrate the proportions between the depth H1 of the f orward portion and rear portion of the air cavity respectively compared to the depth H2 of the planing step area of the rib portion 16. The relat;~n~hip between these values in the forward portion of the cavity area is such that the depth H1 of the air cavity in that region is 10% to 40% greater than the depth H2 of the planing step area of the rib . Pref erably in the f orward region of the cavity the ratio of H1 and H2 is generally less than O . 5 and can incre~se in the aft portion of the c~vity to be more than O . 5 .
~VI~ U~ SEIEET (Rule 26) W0 95/14604 `2 L 7 7 ~ 6 ~ PCTI~Ug4100733 The rela~;nn~hir between the ~orward portion 12 is 3uch that the distance L2 between the step 15 ~iPfin;n~ the forward end of the air cavity and the forward end of the waterline of the vessel 19 as compared to the waterline length Ll of the vessel is of the order of 0 . 05 and 0 . 40 .
If desired the plate 18 may be extended such that it extends for a distance equal to up to half of the length of the air cavity as shown at Figure 6.
In addition, according to a third em})odiment as shown at Figure 7 a plurality of air outlets may be provided in the upper wall of the air cavity 14 and each may be associated with a ventilating plate 18 at a spaced intervals along the cavity .
Figure 8 illustrates the results of testing an example of the ~ ; L shown at Figures 1, 2 and 3. The test model was representative of a vessel of a length of 74 metres and a displ~ L of 700 tonnes. The l~::yr ese:l-Lations provide an indication of the resistance values, degree of trim, the degree of heave, the variation in air cavity pressure and variation of air supply or f low rate . In Figure 8A the solid line indicates the resistance curve of a vessel of corresponding configuration but not in.u~oLcLting a cavity while the broken line illustrates the relatinn~hir of resistance and hull speed of the example of the L .
Similarly, in relation to Figure 8B that figure illustrates by the solid line the angle of trim of an ordinary vessel of corresponding conf iguration to the example while the broken line illustrates the angle of trim of the example of the hull according to the ~ L.
WO 95/14604 ~ PCr/AU94/00733 ~7~6~ - 14 -Similarly Figure 8C illustrates the variation in heave for the vessel without the invention (the solid line) as compared with the vessel with the invention (the broken line ) .
Figures 8D and 8E illustrate the variation in air cavity pressure and air supply flow rate in a hull inuuLyoLaLing the invention as a function of hull speed.
The fourth ~ t of the invention as shown at Figures 9, 10 and 11 has a high speed planing hull 111 which is formed with a forward portion 112 which has a generally conventional ~r~nf; gl~ration except that it in~ul~ola~es a low deadrise planing section in its lower portion and a second portion 113 which inuul~ulAtes a plurality of longit~ inAl ly spaced cavities 114. The forwardmost cavity 114 is separated from the forward portion 112 by a first step 115 which defines the forward boundary of the forwardmost cavity 114. In addition, each of the subsequent cavities is formed with a forwardmost step 115 which each represents the termination of the upper surf ace of the adjacent ~ùlw~ cavity 114. In Figure 9 the wetted area of the hull under design condition is shown as crosshatched .
Figures llA, s and C provide an indication of the cross-sectional c~nfigllration of the hull on the lines A-A, B--B and C-C of Figure lO.
The side of each cavity is defined by a narrow ribs 116 to each side of the hull of equal with or gradually becoming wider f rom the stern to the f orward end of the cavity and which in each case forms lateral and longitudinal extensions of the portion of the hull forward of the respective step.
~ Wo gSl14604 2 ~ 7 7 5 ~ ~ PCT/AU94l00733 -- 15 -- ~ -The upper walls of each cavity 114 are 5ubstantially planar but as shown in Figure g are inrl inPd downwardly towards the stern of the hull where~y the ribs 116 of the respective cavity terminate on the upper wall of that cavity intersecting the plane of the ribs. This occurs immediately prior the transverse axes of the step of the following cavity. The cavities 114 are interconnected by second rhAnnpl R 125 to enable air to flow between the cavities. If desired each second channel may be provided with regulating vanes or like elements which can be adjusted to control the degree of flow through the second ~hAnnRl ~ 114. The adjustment of the regulating vanes or the Like can be effected manually or automatically according to the hull of the vessel and for the degree of roll of the vessel.
The ribs which form the sides of the cavity in the central portion can extend into the third portion aft of the cavity and can have a low positive deadrise at the inner side. In addition, the mid-portion of the third portion is formed to have a positive deadrise to each side of the central axis.
A~ a result of the t~nnf i ~lration of the cavity and the th ~ rd portion of the hull, the air in the cavity is maintained in the cavity and any 10~8 of air is generally controlled. Fur~h~ L~:~ the 1088 of air from the rear of the cavity past the third portion is permitted in a controlled manner through channels 125 which are between the cavity and the 6tern.
The relafinnRhi~ between the forward portion 112 is such that the ratio of distance L2 between the f orward perpendicular of the fuLw~L' ~t extent of the waterline which i6 marked FP and the ~olwc~l, ,.,L cavity step 115 to the waterline length of the vessel Ll is between 0 . 03 and 0.35 .
Wo 95114604 ~ PCTl~1~94l00733 ~
21~564 - 16 -Each cavity 114 i8 pressurised from a pressure source (no~
shown) P~ dated within the vessel which i6 connected to an outlet 117 provided in the upper wall of each cavity 114 towards its forward end. Each outlet 117 i8 asBoCiated with a plate 118 which extends Rcross the cavity in the region below the outlet 117 int~ te of the depth of the cavity. Air delivered from the outlet 117 is delivered into the cavity 114 across the rear edge of the plate 118.
If desired the delivery of air to each of the outlets 117 may be effected from a common pressure source.
Alternatively the air may be delivered to each cavity ~rom an ; n~ p~ntl~nt pressure source. This can improve the p~=l r~ ..r~ of the embodiment in rough sea conditions and in certain situations enables the air being delivered to each cavity to vary, which serves to optimise control of the motion and attitude of the vessel according to sea conditions by the varying the cavity air volume in each cavity. In addition, the pressure maintained in each cavity may vary from the air pres8ure in adjacent cavities .
As shown at Figures 12 and 13 the forward planing portion 12 of the hull of each of the e ' ';- I s can be formed to have a central rib 26, which extends to each side of the central axis. The rib has a cross-sectional profile which is an extension of the profile of the hull to each side of the rib, at ~ny particular location along the rib however the rib serves to project its profile outwardly from the profile of the L~ ; nrl~r of the hull . In addition, the rib extends from a position forward of the water line B-3 to the step 15.
The function of the central rib is to shape the surface of the water in the region of the cavity and which f orms the lower wall of the cavity such that the there will be no ~ ~0 95/14604 2 ~ 7 7 5 6 4 Pcr/AUg4/00733 collapse of that surface and whereby the integrity of the cavity is maintained. The rib reduces in deadrise rearwardly along the hull. If desired the rib can terminate before the step in which case the profile of the hull between the central rib and step remains substantially constant .
In addition, if desired the rib can be formed as a support member which is movable inwardly and outwardly with respect to the hull according to the operating characteristics and water conditions. In addition or alternatively the member may be resiliently supported from the hull to provide some shock absorbing preparation.
In addition, the forward planing portion may be formed with (not shown) a plurality of secondary ribs in the form of f ins or thin chines to each side of the central rib to further control the flow of water past the forward most portion to the second portion.
One ' ined benefit of these features is to reduce the vertical forces or heave exerted on the vessel in rough sea conditions .
If desired the plate of each of the embodiments may be dispensed with and the upper surface of the cavity can be formed with stepped cnnfi~ration where a~r is delivered across the rear face of the step. The stepped upper wall of the c~vity in.c~ LaLes the feature of the plate of previous ' ~ Ls as an integral feature of the hull.
of course appropriate means must be provided to equalise the distribution of air across the rear face of the step.
i Air is delivered into the cavity in each of the ~ i r ts at a pressure such that the vertical force applied to the interior of the cavity is roughly equal to 309~ to 6096 of WO 95114604 PCTIAU94/00733 ~
21~5~ - 18 -the design weight oi~ the vessel. In addition, the total cavity volume of the cavity iB of the order of 5% to 20% of the displaced volume of the vessel.
According to ~mother embodiment as shown at Figure 14 the surface of the third portion is formed to be displacable.
The 6urf~ce of the third portion is formed by several more segments 230 which are pivotally supported ~rom their forward edge to be pivotable downwardly to vary the ;ncl in.q1-;nn of the surface of the third portion. ~he segments 230 are spaced to provide one or more rh~nnel ,:
which are in correspnnri~nrp with one or more channels 220 in the third portion. The 8upport for the segments (shown schematically in Figure 14 at X) i5 resilient to provide some shock ~hgQrhin~ properties. ~he rP~il ir~ntly displacable segment serve to provide some stability against vertical ~, L and reduce shock loadings on the third portion in rough sea8.
It should be appreciated that the scope of the present invention need not be limited to the particular scope of the , ~ - 1; L described above. In particular the invention has application to multi hulled vessels where each hull is fQrmed with a cavity of the form described.
Claims (45)
1. A vessel having high-speed planing or semi-planing hull comprising;
(a) a first portion located at the bow and configured to provide a forward planing portion;
(b) a second portion aft of the first portion comprising a shallow cavity having a forward end defined by a step extending across the hull at the forward end of the second part, a rib located to each side of the hull for the length of the second portion;
(c) a pressurised air source being provided in the vessel and connected to the cavity to deliver air under pressure to the cavity through an outlet whereby the air is distributed substantially evenly into the cavity and in a manner which does not disturb the surface of the water below the cavity; and (d) a third portion aft of the cavity providing a seal at the aft end of the cavity in the form of an aft profiled surface formed with one or more channels extending from the cavity to the stern to permit the controlled flow of air from the cavity such that a substantial portion of the third portion has no contact with the air flowing from the cavity.
(a) a first portion located at the bow and configured to provide a forward planing portion;
(b) a second portion aft of the first portion comprising a shallow cavity having a forward end defined by a step extending across the hull at the forward end of the second part, a rib located to each side of the hull for the length of the second portion;
(c) a pressurised air source being provided in the vessel and connected to the cavity to deliver air under pressure to the cavity through an outlet whereby the air is distributed substantially evenly into the cavity and in a manner which does not disturb the surface of the water below the cavity; and (d) a third portion aft of the cavity providing a seal at the aft end of the cavity in the form of an aft profiled surface formed with one or more channels extending from the cavity to the stern to permit the controlled flow of air from the cavity such that a substantial portion of the third portion has no contact with the air flowing from the cavity.
2. A vessel as claimed at claim 1 wherein the forward planing portion is formed with a central rib which extends to each side of the central longitudinal axis and which extends from a position in the region of or forward of the waterline to the step or a position forward of the step.
3. A vessel as claimed at claim 2 wherein the profile of the lower surface of the central rib is generally of corresponding profile to the hull to each side of the central rib and the sides of the central rib present a step in the profile of the hull.
4. A vessel as claimed at claim 3 wherein the depth of the step varies along the length of the step.
5. A vessel as claimed at claim 4 wherein the depth of the step varies in depth from a maximum depth at the steps forward end and a minimum at the steps aft end.
6. A vessel as claimed at claim 4 wherein the step has its maximum depth at an intermediate position along its length.
7. A rib as claimed at any one of claims 2, 3, 4, 5 or 6 wherein the deadrise of the central rib varies along its length to be at its minimum at its aft end.
8. A vessel as claimed at any one of claims 2, 3, 4, 5, 6 or 7 wherein the central rib terminates forward of the step wherein the profile of the hull between the end of the central rib and the step is of substantially constant profile.
9. A vessel as claimed at any one of claims 3 to 8 wherein the lower edges of the central rib extend beyond the face of the step.
10. A vessel as claimed at any one of claims 2 to 8 wherein the central rib is formed as a member, separately supported from the hull and which is movable from the hull to vary the degree of protrusion of the central rib from the hull.
11. A vessel as claimed at claim 10 wherein the central rib is resiliently supported from the hull.
12. A vessel as claimed at any one of the preceding claims wherein the forward planing portion is formed with a plurality of secondary ribs to each side of the central axis which are configured and placed to control water flow past the forward planing portion such that the water flow over the forward planing portion past the secondary ribs is substantially axial.
13. A vessel as claimed at any one of the preceding claims wherein the substantial portion of the third portion is profiled to have one or more regions of positive deadrise.
14. A vessel as claimed at any one of claims 1 to 11 wherein the third portion is profiled to have a negative deadrise such that the substantial portion of the third portion is located to either side of the central axis and wherein the one or more channels are provided along the centre of said third portion.
15. A vessel as claimed at any one of the preceding claims wherein the ribs extend for the length of the second portion to each side of the cavity to and for at least a portion of the third portion.
16. A vessel as claimed at any one of the preceding claims wherein the substantial portion of the third portion is profiled to accommodate propulsive units for said vessel.
17. A vessel as claimed at any one of claims 1 to 16 wherein the face of the third portion is inclined downwardly from the second portion to the stern.
18. A vessel as claimed at any one of the preceding claims wherein the upper wall of the cavity is inclined downwardly towards the stern.
19. A vessel as claimed in any one of the preceding claims wherein the second portion is formed with a plurality of longitudinally spaced shallow cavities where each cavity is defined by a step extending transversely across the hull at its forward end and a rib located to each side of the hull, pressurised air source being provided in the vessel and connected to the cavities to deliver air under pressure to each of the cavities through an outlet.
20. A vessel as claimed at claim 19 wherein the air source to each cavity is independent of the air source to the other cavities.
21. A vessel as claimed at claim 19 or 20 wherein by the air pressure maintained in each cavity varies from the air pressure in the other cavities.
22. A vessel as claimed at any one of claims 19, 20 or 21 wherein the air pressure in the cavities is capable of being varied.
23. A vessel as claimed at any one of claims 19, 20, 21 or 22 where the cavities communicate with adjacent cavities through passageways.
24. A vessel as claimed at claim 23 wherein the passageways are associated with regulation means to regulate the degree of communication.
25. A vessel as claimed at claim 24 wherein the regulation means is controlled by a control means to control the degree of communication through said passageways in accordance with aspects of hull motion such as hull speed, pitch and roll.
26. A vessel as claimed at anyone of the preceding claims wherein the forward end of the upper surface of the cavity is formed with a transverse second step which reduces the depth of the cavity toward the forward end, said air being delivered to the cavity across the end face of the step and from a plurality of openings in the lower face of the step.
27. A vessel as claimed at claim 26 wherein a majority of air flow is from across the end face of the step.
28. A vessel as claimed at any one of claims 26 or 27 wherein the second step is formed by a plate member mounted transversely across the cavity.
29. A vessel as claimed at claim 28 wherein the length of the second step is between 3% to 35% of the static waterline length of the vessel.
30. A vessel as claimed at any one of the preceding claims wherein the ratio of air cavity volume to static displaced volume of the vessel is between 0.05 to 0.2.
31. A vessel as claimed at any one of claims 26, 27, 28 or 29 wherein the upper face of the cavity is formed with a plurality of longitudinally spaced second steps and air is delivered from the end face and lower face of each second step.
32. A vessel as claimed at any one of the preceding claims wherein the ratio of the length of the waterline of the forward planing portion to the waterline length of the vessel is of the order of 0.05 to 0.40.
33. A vessel as claimed at any one of the preceding claims wherein the air is delivered into the second portion at a pressure such that the vertical force applied to the interior of the cavity is roughly equal to 30% to 60% of the design weight of the vessel.
34. A vessel as claimed at any one of the preceding claims wherein the surf ace of the third portion to each side of the one or more channels is profiled to provide a stable planing surface which is to be in constant contact with the water.
35. A vessel as claimed at any one of the preceding claims wherein the one or more channels are provided with a regulation means adapted to vary the cross-sectional area of the one or more channels.
36. A vessel as claimed at any one of the preceding claims wherein at least the rear part of the third portion is displaceable vertically to vary the inclination of the rear portion of the third portion.
37. A vessel as claimed at claim 36 wherein the rear part is resiliently supported.
38. A vessel as claimed at claim 36 or 37 wherein the rear part is formed with one or more channels which are in correspondence with the one or more channels in the third portion.
39. A vessel as claimed at any one of the preceding claims wherein the ribs are of substantially constant width throughout their length.
40. A vessel as claimed at any one of the claims 1 to 38 wherein the ribs decrease in width rearwardly from the step.
41. A vessel as claimed at any one of the preceding claims wherein the transverse distance between the chines of the hull in the region of the step is at most equal to the transverse distance between the chines of the hull amidships.
42. A vessel as claimed at any one of the preceding claims wherein the ratio of the distance between the forward perpendicular of the forwardmost extent of the water line and the step to the water line length of the vessel is between 0.03 and 0.35.
43. A vessel as claimed at any one of the preceding claims wherein the vessel comprises a mono-hulled vessel.
44. A vessel as claimed at any one of claims 1 to 42 wherein the vessel comprises a multi-hulled vessel.
45. A vessel substantially as herein described with reference to the accompanying drawings.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPM268693 | 1993-11-29 | ||
| AUPM2686 | 1993-11-29 | ||
| AUPM268493 | 1993-11-29 | ||
| AUPM2684 | 1993-11-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2177564A1 true CA2177564A1 (en) | 1995-06-01 |
Family
ID=25644585
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002177564A Abandoned CA2177564A1 (en) | 1993-11-29 | 1994-11-28 | Vessel having a high-speed planing or semi-planing hull |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP0731766A4 (en) |
| JP (1) | JPH09505253A (en) |
| KR (1) | KR960706426A (en) |
| CN (1) | CN1142804A (en) |
| AU (1) | AU668665B2 (en) |
| CA (1) | CA2177564A1 (en) |
| FI (1) | FI962229A0 (en) |
| NO (1) | NO962154L (en) |
| WO (1) | WO1995014604A1 (en) |
Families Citing this family (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2299974B (en) * | 1995-04-18 | 1999-01-06 | Tovarishestvo S Ogranichennoi | Improvements relating to vessels |
| US5787829A (en) * | 1995-09-05 | 1998-08-04 | Kawasaki Jukogyo Kabushiki Kaisha | Apparatus and method for suppressing drag for small planing watercraft |
| US5746146A (en) * | 1996-10-18 | 1998-05-05 | Bixel, Jr.; Charles Gilbert | Surface effect planing pontoon seaplane (SEPPS) |
| US6604478B2 (en) | 1999-11-16 | 2003-08-12 | Bruce R. Barsumian | Hull configuration utilizing multiple effects for enhanced speed, range and efficiency |
| US6789491B2 (en) * | 2000-04-03 | 2004-09-14 | Ishikawajima-Harima Heavy Industries Co., Ltd. | Friction reducing ship and method for reducing frictional resistance |
| GB2382801A (en) * | 2001-12-07 | 2003-06-11 | Gordon Arthur Snape | Vessel hull air lubrication means |
| US6575106B1 (en) * | 2002-04-18 | 2003-06-10 | Advanced Marine Concepts, Llc | Air induction system for marine vessel |
| DE102005052118A1 (en) * | 2005-10-25 | 2007-05-31 | Mathias Schmitz | hull |
| WO2007136269A1 (en) | 2006-05-24 | 2007-11-29 | Dk Group N.A. N.V. | Air cavity vessel |
| CN101857080B (en) * | 2009-04-08 | 2012-04-25 | 深圳市海斯比船艇科技股份有限公司 | Shake-proof anti-drag aerodynamic ship |
| CN101891006B (en) * | 2010-06-29 | 2013-03-27 | 中国船舶重工集团公司第七〇二研究所 | High-speed rounded bilge type boat utilizing air cavity to reduce resistance |
| CN102167133A (en) * | 2011-04-12 | 2011-08-31 | 上海珐伊玻璃钢船艇有限公司 | Rubber dinghy |
| CN106627983B (en) * | 2012-02-21 | 2020-03-17 | 银流技术公司 | System for providing air lubrication layer, operation method thereof and drainage ship |
| RU2530905C1 (en) * | 2013-04-29 | 2014-10-20 | Российская Федерация, От Имени Которой Выступает Министерство Промышленности И Торговли Российской Федерации | Vessel with bottom air cavity |
| SE539235C2 (en) * | 2015-01-13 | 2017-05-23 | Stena Rederi Ab | Vessels fitted with air cavities |
| CN106005242A (en) * | 2016-05-27 | 2016-10-12 | 武汉理工大学 | Air-lubricated ship |
| NL2023149B1 (en) * | 2019-05-16 | 2020-12-01 | Silverstream Tech Bv | Air release unit with diverging side walls |
| CN110450903B (en) * | 2019-07-05 | 2021-04-27 | 哈尔滨工程大学 | Longitudinal flow transition type semi-planing boat |
| CN111591388B (en) * | 2020-06-04 | 2021-01-29 | 中国船舶科学研究中心 | Vortex control air pocket device for ship air layer resistance reduction |
| RU2750686C1 (en) * | 2020-10-29 | 2021-07-01 | Юрий Павлович Кондрашов | Planing hovercraft |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2015907A1 (en) * | 1969-04-18 | 1970-11-19 | ||
| DE1926148A1 (en) * | 1969-05-22 | 1970-12-03 | Weyhausen Kg Maschf H | Flat-bottom boat with increased driving performance without additional energy input to the normal drive |
| AU456662B2 (en) * | 1971-01-13 | 1975-01-09 | Leonard Dirk Stolk | Improved air cushioned planing hull |
| US5000107A (en) * | 1976-11-01 | 1991-03-19 | Burg Donald E | Extended bow and multiple air cushion air ride boat hull |
| US4587918A (en) * | 1976-11-01 | 1986-05-13 | Burg Donald E | Fine entry air ride boat hull |
| GB2060505B (en) * | 1979-10-11 | 1984-11-28 | Walker H | Watercraft |
| US4393802A (en) * | 1980-05-16 | 1983-07-19 | Rizzo Salvatore A | Boat hull with underside channel |
| JPS58152699A (en) * | 1982-03-09 | 1983-09-10 | Akira Ikeda | Bottom exhaust type high-speed boat |
| NL190717C (en) * | 1983-06-07 | 1994-07-18 | Meijer Sjoerd | Vessel with diminished draft. |
| EP0149603B1 (en) * | 1983-07-11 | 1989-05-17 | Donald E. Burg | Flexible bow seal air ride boat hull |
| AU3344684A (en) * | 1983-10-06 | 1985-04-18 | Ateliers et Chantiers De La Manche (Societe Anonyme) | Boat |
-
1994
- 1994-11-28 KR KR1019960702819A patent/KR960706426A/en not_active Application Discontinuation
- 1994-11-28 JP JP7514704A patent/JPH09505253A/en active Pending
- 1994-11-28 WO PCT/AU1994/000733 patent/WO1995014604A1/en not_active Application Discontinuation
- 1994-11-28 EP EP95901996A patent/EP0731766A4/en not_active Withdrawn
- 1994-11-28 CN CN94194890A patent/CN1142804A/en active Pending
- 1994-11-28 CA CA002177564A patent/CA2177564A1/en not_active Abandoned
- 1994-11-28 AU AU11029/95A patent/AU668665B2/en not_active Ceased
-
1996
- 1996-05-28 NO NO962154A patent/NO962154L/en unknown
- 1996-05-28 FI FI962229A patent/FI962229A0/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| AU668665B2 (en) | 1996-05-09 |
| WO1995014604A1 (en) | 1995-06-01 |
| NO962154D0 (en) | 1996-05-28 |
| JPH09505253A (en) | 1997-05-27 |
| EP0731766A1 (en) | 1996-09-18 |
| AU1102995A (en) | 1995-06-13 |
| FI962229A (en) | 1996-05-28 |
| FI962229A0 (en) | 1996-05-28 |
| NO962154L (en) | 1996-07-29 |
| EP0731766A4 (en) | 1997-03-05 |
| KR960706426A (en) | 1996-12-09 |
| CN1142804A (en) | 1997-02-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |