Patent Publication Number: US-6990915-B2

Title: Stabilized watercraft such as a trimaran

Description:
Priority is based on the Provisional application Ser. No. 60/494,099 filed Aug. 12, 2003. 

   TECHNICAL FIELD 
   This invention relates to a trimaran and more particularly to a trimaran having extendible and retractable stabilizing outriggers, i.e. pontoons. 
   BACKGROUND ART 
   Sailboats use wind to move forward in the water. As such, a sailboat must balance the forces of air pressure on the sails against water pressure on the hull(s) to efficiently move the boat in a given direction. This balance, or stability, is achieved using a variety of methods and designs. 
   In the case of a single-hull sailboat, or monohull, stability is achieved primarily through the use of a ballasted keel which lowers the center of gravity. In lowering the center of gravity, the righting-moment on a monohull is located between the center of gravity and the center of buoyancy on the hull. To support the weight of the ballast, the hull of a monohull is made wider which also increases stability. 
   In the case of a multi-hull sailboat, such as a catamaran or trimaran, stability is achieved primarily through extending the distance between the two hulls of a catamaran and/or the three hulls of a trimaran. A multihull therefore does not make use of a ballasted keel. The stability of a multihull is entirely dependent on the boat&#39;s overall width (beam) and the shape of the hulls. 
   While multihulls achieve the goal of sustaining sufficient stability under normal conditions of use, their respective width make them difficult and costly to transport and store. Highway rules make transporting a trimaran wider then 8′6″ via a trailer unfeasible. The hull sizes for these watercrafts also tend to increase their manufacturing costs and hence, a greater cost to the consumer. 
   Boats having relatively narrow hulls and including features to enhance stability have heretofore been known. Typical prior art related to such boats is shown in U.S. Pat. Nos. 4,954,357; 5,647,294; 5,682,831; 5,642,682; 5,515,801; 5,771,715; 4,664,049; 4,512,275; 4,562,785; 4,730,570 and 5,174,233. Boats having narrow central hulls are particularly unstable; however, such boats are normally relatively easy to transport and relatively light in weight. Rigid or fixed laterally-mounted stabilizers for watercraft are known in the art, but such rigs are difficult to transport over land and to store when not in use. Accordingly, it is an object of the present invention to provide a watercraft having stabilizers which are selectively extendible and retractable relative to the hull of the watercraft. 
   Another object of the invention is to provide a watercraft having selectively adjustable elongated floatation members which provide lateral (side to side) stability while at the same time proving longitudinal (fore to aft) stability. 
   SUMMARY OF THE INVENTION 
   The trimaran achieves stability from two outrigger pontoons at each side of the main hull. The monohulls have the disadvantage of not only being heavier because of the weight of the ballast but has only one large hull that is harder to push through the water. The lighter un-ballasted trimaran with three narrow hulls has less resistance through the water. In addition, the trimaran has more stability and can carry more sail area per pound of displacement. 
   The inherent disadvantage of the trimaran is a beam roughly ⅔ the length. A 27′ trimaran would therefore be 18′ wide. Over the years numerous devices have been developed to reduce the beam for transporting the boat on a trailer or for marina berthing in a slip narrower then the fully-extended beam. The most common way to reduce the beam for trailering is to fold the outriggers down. Folding the outriggers down can be done in the water however; It is not suitable to leave the boat in the water for an extended time with the outriggers folded down. Yet another design involves swinging the outriggers aft and into the side of main hull to reduce the beam enough for marina storage. Unfortunately, swinging the outriggers aft can result in numerous disadvantages. In swinging the outriggers aft, the overall length increases which changes the fore and aft pitch of the boat, affecting stability. 
   The system that the inventor has developed is a link box that is half the length of the beam reduction for each side. When the link box rotates about 180 degrees the outrigger is moved inward the required amount. For example, a trimaran that is 27′ long is 18′ wide. The ink box is 28½″ long on each side of the boat. When the link boxes are rotated about 180 degrees, the outriggers turn a semicircular motion horizontally to give the trimaran a new beam of 8′6″. 
   While the concept to reduce beam is rather straight forward, it is complicated in execution. There are two sets of cross arms that join the outriggers to the main hull. Link boxes are part of the cross arms. At the front cross arm the outrigger deck is 30″ wide and 15″ thick vertically. The link box is 28½″ wide and 15″ tall at the outrigger and 20″ tall at the main hull. The link box approximates a trapezoid. In reality, the link box is faired to reduce sea water pounding on the bottom and flat on the top as a walkway. Between the fore and aft cross arms, the outrigger is cut away so that it does not interfere with the bridge deck of the main hull when folded in. The main hull is 8′6″ wide and has attachment points for the link, box at the outside edge and 20″ apart vertically. 
   The link box is 28½″ wide and 9″ to 16″ thick and is also a trapezoidal 15″ in diameter with a fared underside and flat top. At the main hull the attachment points are at the side of the hull and 16″ apart vertically. 
   When the link boxes rotate they tuck into recesses in the main hull. When this is done to both sides, the overall beam of the boat is reduced to 8′6″. 
   To keep the link boxes rotating in unison there in a shelf connected to a pivot on each box, 9″ aft of the main connections. As the boxes rotate the shelf also moves first going out, then forward, finally back in, 18″ further forward than where it started before going back in. The rear of the link boxes curve down so that they act as a cam allowing the shelf to fold down as the link boxes rotate. Conversely, the rotation of the link boxes let the shelf on the outriggers move out. The shelf offers easy movement around the cabin when the trimaran is in sailing trim with an 18′ beam. When hanging down the shelves partially fill in the gap between the underside of the main deck and the top of the outrigger deck. 
   The complication in design is to get clearance for the link boxes to rotate simultaneously into the main hull and the outriggers. The lower part of the cross arm on the main hull has to be designed strong and at the same time faired to prevent a water trap. 
   The link boxes have several important functions. The top and bottom of the boxes take the tension and compressive loads to support the outriggers. The existing invention involves a stainless steel strap bolted to the top and bottom of the link boxes. The stainless steel strap of the link box match with stainless steel straps on the outrigger and main hull forming the cross arm. The pivots are stainless steel vertical bolts. The wall between the top and bottom take the shearing loads. The box itself takes the torsion loads as the outrigger moves from out to in and back again. At the same time the boxes are fared to prevent sea water from slamming against the structure and negatively affecting the speed of the boat. The back of the box curves down 9″ aft of the pivots. The position 9″ aft of the pivot is where the shelf is attached. 
   To keep the link boxes pivoting in unison, a link arm is attached to both boxes 9″ aft of the pivots. This link arm also doubles as a horizontal shelf situated outward from the cabin side when the outriggers are fully extended. As the boxes rotate about 180 degrees, a new part of the box that supports the shelf comes into play. With the back of the box curved down the shelf can now fold down when the boxes are in. 
   The cross arm and link connextion at the outrigger are straight forward. At the main hull, the top pivot to the link of the cross arm is easy. The bottom pivot is difficult at the main hull as the link box goes over the cross arm and the outrigger goes under. The cross arm needs to be held up and fixed fore and aft at the pivot. The recess that the link box goes into must not b a sea water trap. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
     The above mentioned, and other, features and advantages of the invention will become more clearly understood from the following description of the invention read together with the drawings in which: 
       FIG. 1  is a side elevation of the trimaran of the invention with the outrigger pontoons in position for sailing and fully rigged. 
       FIG. 2  is a frontal view of the trimaran with the outrigger pontoon in a non-extended condition as seen out of the water. 
       FIG. 3  is, substantially, the view of  FIG. 2  with the outrigger pontoon in an extended condition. 
       FIG. 4  is an aft perspective view of the trimaran showing the outrigger pontoons in an extended position. 
       FIG. 5  is an aft perspective view of the trimaran with the outrigger pontoons in a non-extended position. 
       FIG. 6  is an exploded view of the important parts of the means for extending and folding of pontoon. 
       FIG. 7  shows the parta of  FIG. 6  in an attached position at the port side of the main hull and to the right of the main hull the starboard pontoon is shown retracted under the main hull as if the latter was transparent. 
       FIG. 8  shows a top partial schematic view of the fully extended pontoon with the arrows depicting the full dimension of the distance of the withdrawal. 
       FIG. 9  depicts a partial withdrawal. 
       FIG. 10  depicts a further withdrawal. 
       FIG. 11  depicts a still further withdrawal. 
       FIG. 12  depicts a continuation of the withdrawal. 
       FIG. 13  shows the completion of the withdrawal. 
       FIG. 14  is a partial top view of link box  16  with the pontoon in an outreach condition. 
       FIG. 15  is like  FIG. 14  with the outreach less severe. 
       FIG. 16  is like  FIG. 15  with the pontoon is further withdrawn. 
       FIG. 17  shows the pontoon more withdrawn. 
       FIG. 18  the pontoon is even more withdrawn. 
       FIG. 19  shows the pontoon completely withdrawn. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows a perspective view of the trimaran, generally,  11  fully rigged with the outrigger starboard pontoon  12  on one side of the main hull  13  and a port side pontoon  14  on the opposite side of the main hull  13 . The outrigger starboard pontoon  12  is connected to the main hull  13  by a forward rotatable link box  15  and at the aft of the main hull  13  by aft rotatable link box  16 , both of which act as connectors between the sides of hull  13  and their respective outrigger pontoons  12  and  14 . A like structure exists at the opposite side, i.e., port side, of the main hull  13 . 
   The trimaran  11  is fitted with conventional rigging  9 , conventionally and suitably mounted on a vertical mast  20 . The mast  20  has a conventional boom  21 . The trimaran  11  as depicted is seen to have an outboard motor  22  shown in a swung up position, i.e., out of the way in an unutilizable position. The trimaran is depicted with a conventional cabin  23 . 
   While more will be taught about the link boxes  15  and  16  and their respective functions, at this juncture it is pointed out that the upwardly facing surfaces define an essentially cam whereby the thickness of the link boxes progressively varies so that its thinnest is presented when in one position closest to the outermost side of the hull  13  and the thickest portion is presented at the same locale when the pontoon is in an outrigger position. 
   It is also pointed out that each of the respective rotatable circular link boxes are pivotally secured between respective vertical pin points on the hull  13  and respective inwardly depicted projections  19 , fore and aft on each of the pontoons  12  and  14 . Said projections  19  acting together with their respective link boxes  15  or  16  as part of the outrigging of the said pontoons. 
   From  FIG. 2 , the pontoon  12  is shown to be in a withdrawn condition laterally to the main hull  13  with the forward link box  15  shown in an inwardly pivoted condition, shown to be in an overlying condition of outrigger projection  19 . Note that the thickest part of link box  15  is facing outwardly. The same positions are attendant the aft link boxes  16  and projections  19 . Note the end view of a shelf  24  which is positioned downwardly in  FIG. 2 , additional information in connection therewith will be provided hereinafter. 
   In  FIG. 3 , the fully rigged trimaran is a front view. The starboard pontoon  12  is shown in a laterally extended condition with the link box  15  outwardly pivoted whereby the pontoon  12  is at its outermost reach to thereby gain the utmost stability. The port side is similarly depicted. Note shelves  24  which are shown in an essentially horizontal position and overlie a portion of upwardly facing cam surfaces of link boxes  15  and  16 . 
   The said shelves  24  are pivotally secured to the thickest end of the respective link boxes by a short linkage with essentially a universal joint whereby each shelf acts as an elongated linkage between the fore and aft link boxes  15  and  16 , on each side of the trimaran so that the fore and aft link boxes on a given side will act in unison. As stated heretofore, the shelf  24  rests essentially horizontally on the cam surface of the fore and aft link boxes. 
     FIG. 4  is a perspective partial view of the trimaran  11  with the starboard pontoon  12  depicted in a laterally extending position with a clear view of aft pivotable link box  16  and forward link box  15  are seen extending towards projections  19  to which they are pivotally secured. It will be noted that the space defined between the outer edge of the shelf  24  and the pontoon  12  is breached with a net  25  secured there between to catch items that without the net could fall into the water. The net  25  naturally folds into a plurality of horizontal folds as the starboard pontoon  12  moves laterally in the direction of the hull  13  to a collapsed position. 
   As the support and strength imparting brackets as seen or will be seen in connection with the various link boxes  15  and  16  have an important role to play in the present invention, more information will be provided in connection therewith hereinafter. 
     FIG. 5  shows the laterally withdrawn pontoon  14 . Note therefrom the positioning of the shelf  24  shown to be essentially vertical and has filled the gap, that otherwise would be present, between the upper leading edge  13   a  of the hull  13  and the top surface  14   a  of pontoon  14 . 
   In the configuration of the trimaran shown by  FIG. 4 , the vessel has an approximate 18 foot beam. In the configuration of the trimaran shown by  FIG. 5  the beam is only 8 feet 6 inches which is eminently acceptable for highway trailering. 
     FIGS. 6 and 7  should be viewed together.  FIG. 6  shows the operable components as shown in an exploded fashion. The pontoon  14  shown is on the port side. Forwardly, the pontoon  14  is seen outfitted with projections  19  both fore and aft. The foward projection  19  is fortified with a strong cross-arm  32  ending in an eyelet  31  to which link box  15  is pivotally  15  attached through a bolt  30  secured to strong bracket  28  which is secured to link box  15  from arcuate end to an opposite essentially straight edge  29 . A short lever  34  is attached to a pivot point  39 , the latter is pivotally attached to the hull  13  at an outer edge  50  of a recess  51  on the side of the hull detailed to accept the major portion of the link boxes  15  and  16  when the pontoon  14  is in the withdrawn position. The shelf  24  has a pivot point  37  detailed to accept the outer end of lever  34  in a pivoting and hingeing manner. 
   The aft link box  16  of pontoon  14  is detailed in a similar manner wherein projection  19  is fitted with a strong bracket  49  which terminates in a bearing eyelet  35  which is pivotally attached at  36  to one end of a strong bracket  38 . The other end is attached as heretofore with regard to box link  15  to a bearing eyelet  40  to which is attached a lever  41 . The end of lever  41  is universally attached to pivot point  42  at the aft end of the shelf  24 . The shelf acts as a linkage to insure that link boxes  15  act in unison. 
   In  FIG. 7 , the pontoon  14  on the port side is shown assembled with the components shown in FIG.  6 . The bearing  40  is fitted with a crank handle, not shown, detailed to provide a mechanical advantage to rotate clockwise link box  16 ; to thereby secure arcuately clockwise, said link box  16  towards and into a recess  51  in hull  13  while at the same time shelf  24  acting as aa linkage acts on the pivot point  39  to move link box  15  clockwise into a similar recess  51  in the fore part of the port side of the hull. The concomitant movement of the clockwise multi-degree movement of the link boxes  15  and  16  laterally inwardly move the pontoon somewhat forwardly of the hull and back thereby completing the designed withdraw or lateral collapse. A similar path is described in reverse when the pontoon is moved to its outrigged position. 
   On the starboard side of the hull one can see the lateral inward positioning of the hull and respective link boxes  15  and  16  in a manner as if that side of the trimaran was transparent so the retracted components can be seen at rest. 
     FIGS. 8 through 13  are schematic renditions designed to show in greater clarity the ingenious function of the component parts to effect the smooth lateral movement of the pontoons  12  and  14 . These drawings should be viewed in seriatum to show the operation in sequence. Each of the views is depicted as a top view. Starting with  FIG. 8  one can see that the pontoon  14  is in its furthermost outrigged reach. The bold arrows depicted are merely for the purpose of illustrating the extent of the lateral movement of the pontoon to achieve essentially a complete withdrawal as seen in the final rendition of FIG.  13 . Note the link box  15  of the pontoon  12  and link box  16  of the aft portion of the pontoon. Each link box  15  and  16  describe from a top view a sort of trapezoidal housing configuration. Link box  16  is connected to the pontoon at  30  by a vertical pivot  31  and is secured to the pontoon by a strong metal strap  32 . Likewise link box  16  is secured to the pontoon  14  by a vertical pin  36  and is secured to the aft portion by a metal strap  49 . An elongated metal strap  38  is secured to the surface of link box  16  and terminates substantially near the edge  43  with a vertical pivot point  40  to which is pivotally attached a relatively short lever  41  ending in a vertically extending pivot point  42  ending in a vertically extending pivot point  40  which is attached near the top edge portion of the shelf  24 . Similarly, link box  16  has a metal strap  38  secured to the link box  16  which also terminates near the edge  43  with a vertical pivot point  40  to which is attached a relatively short lever  41  terminating in a vertically extending pivot point  42 . Pivot  40  has a crank handle having a mechanical advantage whereby the link box  16  may be rotated clockwise through an angle into the aft recess  51  on the port side of hull  13 . 
     FIG. 9  depicts the same structure as in  FIG. 8  but depicts a small angular clockwise motion of each link box  15  and  16  moving about their respective pivot points  39  and  40  with the pontoon also describing a relatively small foreward linear motion. 
   As stated the main hull has suitable recesses or cavities built there into at their respective sides to accommodate the laterally extending link boxes  15  and  16 . These recesses or cavities are relatively simple to fabricate as the main hull is made of epoxy and fiber glass. 
   In  FIG. 10  one can easily observe a still further motion of link boxes  15  and  16  in a further follow through. Then,  FIG. 11  shows a still further follow through, but in this position shelf  24  is in a stage of hinged arcuate movement from a near horizontal position as in  FIG. 8  to the angular result while acting as a linkage means to synchronize movement between link box  16  and link box  15  which is driven by the former. In  FIG. 12 , the link box  15  and link box  16  have almost achieved their complete clockwise arcuate motion and the shelf  24  is more vertical. In the final depiction the respective link boxes  15  and  16  are in their most extreme position with link box  16  positioned in a recess  511  located in the side of the hull  13 . Similarly, a recess  51  is provided in the aft portion of the side of hull  13 . In its final position, as depicted in  FIG. 13  it will be noted that the arrows depicted illustrates the extent of the withdrawal. At the same time the pontoon has returned to its same fore-aft position as when the pontoon was in its extended position relative to the main hull  13 . 
     FIG. 14 through 19  should also be viewed in seriaturn as  FIGS. 8-13  and are the same views but only of the aft position of the portion showing link box  16  and angle enlarged for purposes of achieving even greater clarity. The reference numerals are the same as the previously recited discussion pertains, especially with regard to  FIGS. 8  to  13 .