CA1127911A

CA1127911A - Sailing rig

Info

Publication number: CA1127911A
Application number: CA352,852A
Authority: CA
Inventors: Anthony M. Williams
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-05-28
Filing date: 1980-05-26
Publication date: 1982-07-20
Also published as: AU5858280A; EP0020121A1

Abstract

ABSTRACT OF THE DISCLOSURE

A rig for a sailing craft including support means adapted to support a sail assembly on the leeward side of said craft, said sail assembly being disposed and supported in such a manner that the force exerted thereby acts through the centre of resistance of said craft.
The rig of the present invention eliminates or minimises capsizing moment present in conventional sailing craft, thus en-abling a low stressed and light weight speedy craft to be constructed.
Also, the present rig allows the elimination of a rudder or other steering mechanism which reduces the cost and complexity of the craft.

Description

llZ79~1 T~IS I~TV~2~IGN relates to sailing craft and ~ore particularly to a rig for such cra~t.
Conventional sailing craft have the s~il approxi~ately above the centre of the body of the craft which means that the centre of effort prod~ced by the s?il is above the centre of resist~nce of the crRft causirAg a ca~sizing mo~ent. In order to overco~e this moment and support the conventional sailing rig~ the vessel must be counter-balanced by ballast and~or a buoyancy shift righting oment. ~he resultant stresses produced by the sail and counterbalancing re~uire that a vessel must be constructed strongly to resist such stresses.
~'urthermore, the conventional sail at its best ~enerates small turning moments which must be constantly corrected with a steeri~lg mechanism~ i~he vast majorit~
of vessels therefore re~uire a rudder to maintain zero turning moments so that the vessel remain~ on a straight course.
Both the above effects are undesirable in that they decrease the speed of t~e vessel and increase the stresses on the vessel and its fittings. ~urther, the provision of ballasting or extra buoyancy and steering mechanis~s san be complex an~ costly.
The present invention ai~s to overco~e the above disadvantages of conventional saili~g c.aft by providin~ a sailin~, L'ig which elil~inates o~ ~ini~ises the capsizing ~o~ent thus enab1ln, a lo~ stresced and l~.ght weight speed~ cra.'t to be constru^tei. r'l~rt~er~o~e, ..~,,~

llZ7911 _ ~ _ the rig of the invention allows the elimination of a rudder or other steering mechanism which reduces the cost and complexity of the craft~
. With the above and other object~ i~ view, the ~nvention resides broadl~ in a sailing vessel of the type includi~g a hull assembl~ and sail assembl~ adapted to be mcved longitudinally relative to said hull assem~ly so that the centre of effort of said sail assembly may be selectively varied to cause a change of direction of ~aid hull assembiy with respect to the wind direction;
ckaracterised in that said sail assembly includes a sail and su~porting means therefor, said sail having a supported luff and said supporting means pivotall~ supporti~g said sail on said hull assembl~ at a position substa~tially centrally of said luff foF pivotal movement about a trans-verse axis whereb~ said luff may be pivoted about said transverse axis to an operative leading po~ition with respect to either end of said hull ass~mbl~ selected to be the operative leading end of said ~essel and there bein~
provided control means to maintain said sail in its oper-ative attitud~.
Preferabl~, the craf~ to which the rig is applied is one which is s~mmetrical about a line transverse to the lo~itudi~al centre line of the cra~t such that the craft

2~ is able to sail in either direction. ~hat is, the bow of the craft whilst sailing in one direction becomes the stern when ~ailing ln another direc~ion~ Preferably also the craft is a proa 7 the main hull 3~ ~hich alwa~s remaîns ~o wind~ard.

~lZ7911 - 3a -In order that the invention may be more readil~ 1ln~erstood and put into practical effect, reference will now be made to the accompanyi~g drawings which illustrate the invention and wherein:-Fig. 1 illustrates a schematic elevational view of a sailing craft incorporating the rig according to the invention;
~ig. 2 ill~trates a schematic end view of the craft and rig; and ~ig. ~ illustrates a schematic plan view of 11~7911 the craft and rig.
Referring to the figures, there is sho~n a saili~g craft 10 having hulls 11 and 12 joined by a deck-ing 30 which incorporates cross beams with the hull 12 comprising an outrigger to the ~ain hull 11, the craft being in the form of a proa and sy~metrical about a line transverse to the longitudinal direc~ion of said hulls. The rig includes a sail supporting mechanism which comprises a stub mast 13, a support pole 14 pivotally mounted adjacent the base of the mast 1~
and a line 15 running from the remote end 26 of the support pole 14 to the top of the mast 13. The mast 13 which is of li~ited height as illustrated in Fig. 1 is supported on the hull 11 by stays 16. Pivotally 1~ mounted at the remote end 26 of the support pole 14 is a sail assembly which includes a sail 17 attached to a luf~ spar 18 ~"'nich is'~ivotal ly att~ched to pole end 26 and a boom 19 which extends fro~ end 26 to a free corner 20 of the sail 17~ The sail 17 in this e~bod~,ment is of generally isosceles triangular form, the unequal side thereof forming the s~il lu~ and being attached in a convertional manner to the spar 1~.
The sail, being of isosceles form t`~erefore has the leech and foot of equal length so that the sail assembly is sym~PtricRl ~d of simil~r s'nape in either direction of sailinO.
The spar 1~ prefPra31,; has a sail trac'~ on theleeside thereof to receive the s~il edge ard provide for a clear air flo-~ therep?~st.

~ he support pole 14 is under co~pression only in calm conditions, otherwise it is in tension when the winds are of medium and strong strength. As shown in the figures, the main hull 11 is to windward and always remains in this position relative to the wind whilst the sail 17 is always to leeward of the centre of resistance. The purpose of the outrigger is to provide the craft with static stability and provide a sheeting base for controlling the sail but it has little reserve buoyancy so that there is little stress on the outrigger hull. The drawings show the normal position of the sail rig when the vessel is sailing to windward on a starboard tack with the wind direction indicated by the arrow X in Fig. 3 and the point ll' on the main hull 11 indicating the bow of the vessel while point 25 indicates the stern.

The rig also includes a nu~ber of control lines which are not sho~n in the drawings ~or the purpose of clarity. One line A extends from the point 20 at the end of the boo~ 19 through a pulley at point 21 on the spar 18 and back to a cleat near point 22 to support the end of the boom 19. A further line B
extends from a point 23 on t.~e spar 18 and through pulle~s at the points 24 near the end of ~he outrigger 12 and 25 on the end of the hull 12 to another cleat near poi~t 22 to control the raXe of the spar 18. A
third line C e~tends from a point at the free end 26 of the pole 14 through a pulley on the endll' of the A

11279:1 1 main hull 11 and back to another cleat near point 22 to pull the rig forward. A main sheet D extends from the point 20 at the end of the boom 19 to a further cleat at point 22. The area around point 22 constitutes a central control area where all the lines terminate and from where the craft can be controlled. The`lines A, 3, C, and D are all in tersion while the vessel is on a starboard tac'~. Line A on this tack supports the end of the boom, thus freeing the leech to maintain the sail at the correct angle as shown in Fig. 2. Line B puts tension on line A and controls the luff spar rake, whilst line C acts to pivot the whole rig forward about the axis of the mast 13 against the pull of line ~.
Lines A, B and C are duplicated on respective opposite sides of the spar 18 and the mast 13 for sailing on a port tack. Furthermore, lines B and C can be uncleated and joined together for quick manouvering in confined spaces which maintains desired luff spar rake for all rotational positions of the sail supporting mechanism.
Turning moments are automatically zeroed by virtue of the sail being to leeward of the centre of resistance of the vessel and the force exerted by the sail ~cting through the centre of gravity. The 2~ boat is self steering because of the relative position of the centre of effort of the sail and the centre of resisGance. Should the boat go slightly off course, a small turning moment is auto~atically created to turn the boat back on course. All that is needed to steer A

llZ79:~

the boat is an ability to swing the sail fore and aft.
To lay off the position shown in the drawings, the sail is simply swung forward by tension on the line C which rotates the support mechanism about the axis of the mast 13. ~he sail force then does not act through the centre of resistance but causes a turning moment about the centre of resistance and the vessel to turn until the sail force again acts through the centre of resistance to thus establish a new set course..
When it is desired to tack, the support pole 14 is rotated aft towards.the stern 25 which causes the vessel to point higher into the wind and across the wind until the boom 19 is swung or flips to the other side of the mast 13 and the vessel proceeds on its new tack with the old stern point 25 constituting the new bow of the vessel and the old foot of the sail becomes the new leech. In very calm weather, the luff spar 1~ can be rotated to a vertical position to give a higher aspect ratio sail shape.
~he above described sail rig as well as reducing turning moments in the vessel to a negligible amount also keeps the capsizing moments negligible as the incl.ination of the sail and its lee-~ard position ensures that the propulsive force pulls tnrough the centre of resistance. Furthermore, as the force is acting in this m~nner, the boat is partially lifted out of the water in a similar fashion to ~he windward hull of a catamaran due to the sail providing an upward vertica' component of driving force causing the llZ79~1 ap arent displacement to decrease which consequentially gives the vessel a higher speed potential.
One advantage of the foregoing described craft is that the hulls can be made of relatively light materials. For example, in a sixteen foot proa design, one person with a strop between the cross beams can carry the boat fully rigged down to the beach. Due to the low stress on the hulls quick release cross beams can be easily arranged which enable the hulls to be quickly disconnected and placed on a car roofrack for easy transport which reduces transport costs and the amount of storage space required.
As a modification an extended dec~ portion ~1 may be arranged to windward of the main hull and a footwell 32 recessed into the hull as shown in ~ig. 3.
This will improve crew comfort and move the lateral centre of gravity very close to the centre of the main hull which will reduce wetted surface area. In further modifications of the rig, an equilateral triangular shaped, a square shaped or ri~id "wing-type" sail may be employed. It is also desirable that buoyancy be built into the rig preferably the luff spar to stop complete overturning and assist in righting if a capsize does occur.
~he sail as illustrated in the draw1ngs is a variation of an o'd lateen type of sail which has low stress factors on both the spars and the sail cloth.
It also has a very low centre of effort and does not have to be finely tuned as in conventional rigs.

llZ79~1 It is also envisaged that instead of using.
a system of iines to control the rig, mechanical equivalents may be employed. For example, in place of the main sheet steering m~y be achieved by the use of steering vanes arranged behind the leech of the sail.
The rig of the invention may also be used on mono-hulled craft with ballast although a ~.ulti-hulled craft is preferred for simpl1city in achieving static balance.
While the above has been given by way of illustrative example of the invention, all such modifications and variations which are apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as herein set forth and defined by the claims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A sailing vessel of the type including a hull assembly and sail assembly adapted to be moved lougitud-inally relative to said hull assembly so that the centre of effort of said sail assembly may be selectively varied to cause a change of direction of said hull assembly with respect to the wind direction; characterised in that said sail assembly includes a sail and supporting means therefor, said sail having a supported luff and said supporting means pivotally supporting said sail on said hull assembly at a position substantially centrally of said luff for pivotal movement about a transverse axis thereby said luff may be pivoted about said transverse axis to an operative leading position with respect to either end of said hull assembly selected to be the operative leading end of said vessel and there being provided control means to maintain said sail in its operative attitude.

2. A sailing vessel according to Claim 1, wherein said hull assembly includes a pair of spaced apart hulls comprising a windward hull and a leeward hull and wherein said sail is supported to the leeward of said windward hull.

3. A sailing vessel according to Claim 2, wherein said windward hull is a windward hull of a proa and said sail is positioned so that its operative centre of effort acts substantially through the centre of gravity of said hull assembly.

4. A sailing vessel according to Claim 3, wherein said sail is triangular and a boom extends from the centre of said luff to the free corner of said sail.

5. A sailing vessel according to Claim 4, wherein said triangular sail is of isosceles shape, the unequal side thereof constituting the luff of said sail.

6. A sailing vessel according to Claim 5, wherein said supporting means includes a stub mast, a support pole extending upwardly and outwardly from the base of said mast and a line between the remote end of said pole and the top of said mast supporting said pole at an angle to said mast, the remote end of said pole being pivotally connected to the luff of said sail centrally thereof and said pole being pivotal about said stub mast to move said sail assembly longitudinally relative to said hull assembly.

7. A sailing vessel according to Claim 6, wherein said control means include control lines extending from said sail assembly towards a central operating position on said windward hull.