CA1297348C - Boat hulls - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE:

The present invention is concerned with a boat hull.
The boat hull includes a channel shaped bottom part having a keel and an undersurface having a plurality of corrugations which are located on each side of the keel thereby forming a plurality of alternating hills and valleys. Each valley has a vertex and each corrugation is V shaped in section there-by providing an oblique line and a substantially horizontal line characterized in that in section the successive lines of slope formed by adjacent oblique lines of the corruga-tions form a multiplicity of angles of deadrise which are all greater than the substantially constant angle of deadrise formed by joining a line through a row of vertices in section.

Description

3 ~3 This invention relates to an improved boat hull.
Hitherto, a first type of conventional boat hull included a plurality of planing elements or strakes on each side of the hull between the chine and the keel. These strakes were usually spaced from each other and usually 3-4 strakes were provided on each side of the hull. The strakes usually extended from the bow to the transom.
It w~s found in practice that conventional boat hulls of the type described above were disadvantageous in providing a relatively turbulent ride when the boat hull planed through the water. It was also considered that boat hulls of the a~ovementioned type were costly or relatively difficult to manufacture.
In a second type of conventional boat huil there was provided boat hulls derived from a "clinker~ or lap strake type design wherein each side of the hull between the chine and the keel was corxugated forming a plurality of alternative hills and valleys wherein each corrugation extended from bow to transomO ~owever this type of hull was found to be disadvantageous for similar reasons as described above in relation to the first type of conventional hull.
It therefore is an object of the present invention to provide a boat hull which may alleviate the abovementioned disadvantages associated with the prior art.
According to the present invention, there is provided ' ~

~, y ~
- la -a boat hull includin~ a bow, a transom, a pair of hull slde~, a ohannel ahaped bottom part havlng a keel and an under~urface havlng a plurality of aorruyation~ whlch are loaated on eaah ~ide of the kael and loaated batwean the k~el and a boundary or ahine o~ the hull under~ur~aae ~nd an a~oaiated hull side thereby orming a pluxality of alternati~g hlll~ and valleys with eaoh valley havlng a vert~x and eaoh aorrugatlon beln~ V ~haped in ~eation thsreby p~ovldlng an oblique llne and a ~ub~tantlally horlzontal line oharaaterlsed in that ln ~eotion ths ~uooes~ive llne~ of th~
~lope ~ormed by ad~acent obl~qua linas o the oorsugation~
form a multiplicity o angle~ of deadri~e whi~h are all greater than the ~ub~tan~i~lly aon~tant angle of deadri~e form~d by ~oining a line through a row of vertlaes ln ~e~tion and ~ald plur~lity od aorrugation~ lnalude an outermo~t plan~ng ~orxugatio~ ha~ng a~ end tsrminating at or ad~a~ent the tranuom, o~e or more in~ermedlate planlng aorrugations having end~ tarminatlng ~hort o ~he end o~ tha outermost pla~ing aorrugatlon and. ~n lnnermo~t planlng oorr~gation loa~tad ~d~aoant to the kael havlng an end terminating ~ho~
o~ th~ end(~) o~ ~aid ons or more lntermedl~te planlng corruga~lon8.

`~7~

The feature of the planing corrugations having differing terminating ends as described above means that a substantial advantage is achieved because ~he planing corrugations or strakes are responsible for controlling lift created by water flow when the hull is in motion. This is achieved by changing the direction o~ flow of the water, thus creating lift. It is thus important to vary the length of the planing corrugations to control the longitudinal lift of the hul]. In this regard the load carrying ability of a planing hull is directly relevant to the amount of lift generated by the hull. Positioning of the load therefore is important as the ~ift generated in the hull must be located in the required area to carry that load in a correct planing attitude. The desirable attitude is ~etween zero and eight degrees angle of attack. To control this angle of attack bet~een these limits means that the longitudinal lift must also be cont~olled and to this end the planing strakes have terminating ends as described above.

In contrast if the planing corruga~ions were continued through to the transom or stern of the hull more lift would be generated in the stern. Because the planing area of a mono-hull is triangular in shape with the base of the triangle being at the stern and the apex of the triangle b2ing towards the bow considerably more lift is generated ~I~J ~ :~

- 2a -because of the increased planing area at the stern. Therefore to continue the planing corrugations through to the stern generating ever further lift would create an undesirahle planing attitude when the load is being carried forwardO
~ he Nangle of deadrise" defined herein means an angle formed by a transverse sectional line defining the underside of the hull to the waterline attitude athwartships.
The hull of the invention preferably has 2-4 corrugations on each side thereof adjacent the keel and /

3 ~

suit bl~ ch corrugat~on may e~tend from bow to transom with the transom end or each corruqation terminatiny short of an adJacsnt outer~ost corrugation.
The hull or tAe invention may also be of the "hard chine" variet~t whereln the sides of the boat hull e~tend out-lardl~ and upwardl~j f-om each side of the hull unders~r- ce loc~ted adjacent t:~e ~eel. ~owe~rer, the hull may be o the "solt chine" variet~ i' necessary wherein the tsansition betwesn the hull undersur-ace and side is no~ a shar? one as in the case of the "hard chine" variet~ but is usuall~f rounded and the sides of the hull may e~tend upwar~ly or inwardly f-om an associated undersurface.
T, is also pr~;~er=ed that the hull of the invention inclu~es a chine plan~n~ strake whic~ is not pr~sent in hul's or the cllnker ~uil. or derived f_om a clinker .~lpe constr1c-lon as rererr-d to above.
Refer2nce ma~ now be made to a prefe~rsd e~ncDldiment of the invention as shown in the ac_ompanying dr~winas wnerein:-F-G 1 is a bc~tom plan view of a boat hull cons-_ucted in ac_ordance with the invention;
FIG 2 is a ver~c 1 sectlon through line A-A of FIG
l;
FIG 3 ls a ve~ical sect~on through l-ne B-B of FIG
-_ l;
FIG 4 -s a ve~.ical sect~on through t ' ne C-C or FIG
l;

~i$~3~

FIG 5 is a rear perspective view of the hull shown in FIG 1;
FIG 6 is a verLical section through ~he hull of FIG
1 as well as a vertlcal section throu~h a conventional boat hull as described above;
FIG 7 is a sche~atic vertical section through the boat hull or FIG 1 illust~ating the planing corrugations const~ucted in accordânce with the invention; ana FIG 8 i5 a schematic vertical section of the hull of FIG 1 as well as a v~_t~cal sectio~ t~rough a conventional boat hul~ ustr~ting the advantages of the boat hull of the inven~ion in comparison to the prior art.
In FIG 1 there is shcwn boat hull 10 having keel 11, planing corrugatlons 12, 13 and 14, planing plank 15, t-ansom 16 and bow 17 as well as chlne planing element 13.
The underside of hull 10 is svmmetrical about an a~is 19 of bilateral symmetry. It will be noted that the transom end of corruqation 1~ t2r~inates at transom 16 while the transom ends or cor-u~ations 13 and 14 ter~inate progressively for~ardl~r of cor-ugation 1~. Each cor~uaation 17, 13 and 14 includes a horizontal e~osed surface 20 an~ obliaue or slo~ing sur-ace 21. The hull also has sides 22.
As best shown in FIG 5 the transom ends 23, 24 and 25 cr each planing cor_ugat cn 12, 13 and 14 provide reduced pressure are3s 26 which prov~de water tur_u'encP during t-avel OI t~e hull ovzr the water whlch reduc2s propulsion or t:~e neec ror ext~_ hcr_c~ower ~n r~gard to t:ne propulslon . ~

~,~f~?7 ~ 3~8 uni. or engine. ALso shown ~ rear uncorrugated part 26A
which also may provide water turbulence during travel having transvexse step 26B.
In FIG 6 on the left side is shown hull 10 cons.ructed in accordance with the invention and hull 30 of conventional design havina, spaced strakes 27, 28 and 29 which all provide a subs' ntia7ly constant angle of deadrise def7ned by angle A. Each stra~e is separated from each other by spaces 31 and e-ch strake ~7, 28 and 29 has a ver.lc~l surface 32 and horizontal surrace 33 in contrast to the 21an~ng corrugations or hull 10 which have an oblique sur--c_ 21 and hori70nt71 surface 20. Each planing cor-uaati.on 17, 13 and 1~ provides variable angles of deac_~se BT, C~ and D~ as shown measur~d by their respective ohlicue surfacos 21.
Also as shown in FIG 7 each corrugatqon 12, 13 and 14 has a ver.e~ 35 an~ peak 36. A dotted line 3~ drawn tnrouch eac:~ verte~ iS provides a substantially cons~ant an~'e of deadrlse anc e_c~ anale of deadrise ~T, CT and DT
is areater than the anqle or deadrise defined by line 37 wnir~. cor~es?cnds to ansle A in FIG 6.
~ulls const_~cted in accordance with the invention wil7 ~e found to be advantageous ha~ing regard to the prior a_ hu'ls re-ar_cd to above. Thus the increas2d ang7e or de_c--se a_~orded to e=ch planing corrugation provides a 50--C~ or more non tur~ule~t ride and manuTacture is enhancQd. The prov~sion Gr pressure areas 26 provides tur~ulencQ raaucing the ne_d for additional prooulsion and . ' 73~

t~ s is a Eeature àis~inctl y zcvant~gerus having regard to conventlonal boat hulls de~ v~r' frc~ or constructed in ac^orGanCe with a cl n.~er t~tpe desi~n.
A convent~ onai Uae~? -lee" ~OW6- bo~t hull is l .~ited t~ a deadr 52 anqls oS appro~ci.. ? .~ly 20-23 degr24s .
recarc to a conve~iona1 bcat hull ~:se dea~r~ se ar~gle of 2û-23 dearees cannot usual~ ~ 3~ e:~c~ec~e_ }:ecause a gre~ter an~7~ deadrise c~ es Lns ~bili~ 2' res~ when the boat is s~ztionary. Th~ bc~t hull o~ th~ L.~/ention in being a~le 10 to obta~n for example a 3a de~,~2es ~nc~e of deadrise ap~;ro:~imately gî~es a iess tuY ulent r de to passengers.
T~ s f~ature is illus.,~ated ~^ PIG 8 wr.arein at rest the hu 1 10 of the invent on assu~es a w~a~_ water line A ~han cor.vent~ onal hull 30 which prcvides a r.2rrower water line B
}5 The wide_ waterline A proYide~ grea.a- s'ability ln rough condi~ions or when a load is ~plie- such as the arrows shcwn due ~o movem~nt ~f p2sse!lgers ~or exampl e . Th~
conve~t~ onal boat hul' 30 bec~use c~_ e~tra buoyancy beoause it is deepex in the water wher compæri~g the respective ke~l 2~ po~ t~ons 11~ and llB has a much re~ucE~ wæ~erline be~m or wic'h a~ shown and becaus~ of this is ~ery ~mstable a~ rest.
A f urther d ~ sadvantace of cDn~ntional boat hulls is tnat the greate~ e angle of deadr-se the narrowe~ ~he .
hu'1 has 'o be t~ rem2~n s'~'e at res.. Th~s 1~ shown by 25 w~ ct~s C and ~ refar_ad to i~ ~IG 8 . The anales of ce~ rise aand ~Bare ats~ shcwr..

h~,.. 1..~;

Claims (4)

1. A boat hull including a bow, a transom, a pair of hull sides, a channel shaped bottom part having a keel and an undersurface having a plurality of corrugations which are located on each side of the keel and located between the keel and a boundary or chine of the hull undersurface and an associated hull side thereby forming a plurality of alternating hills and valleys with each valley having a vertex and each corrugation being V shaped in section thereby providing an oblique line and a substantially horizontal line characterised in that in section the successive lines of the slope formed by adjacent oblique lines of the corrugations form a multiplicity of angles of deadrise which are all greater than the substantially constant angle of deadrise formed by joining a line through a row of vertices in section and said plurality od corrugations include an outermost planing corrugation having an end terminating at an adjacent the transom, one or more intermediate planing corrugations having ends terminating short of the end of the outermost planing corrugation and an innermost planing corrugation located adjacent to the keel having an end terminating short of the end(s) of said one or more intermediate planing corrugations.

2. A boat hull as claimed in claim 1, wherein the undersurface of the hull is divided into a corrugated part containing said plurality of corrugations and an uncorrugated part located adjacent a transom end and a transverse step is provided separating the corrugated part from the uncorrugated part.

3. A boat hull as claimed in claim 1 wherein there are provided 2 to 4 corrugations on each side of the hull.

4. A boat hull as claimed in claim 2, wherein each corrugation extends from a bow end to said transverse step with the transom end of each corrugation terminating short of an adjacent outermost corrugtion.