Assembling the Catapult catamaran: the frame

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  Catapult is a one-design class for hull, spars and sail, still allowing helms latitude in sail controls and details of rigging---and similarly boat assembly is basically the same for all boats, while individual sailors work out their own best routines. The basics and some of the different approaches are described here. (Whichever technique is used, getting into a familiar routine makes it easier and quicker.)  

    Above: Chris rigs cheerfully in the sunshine beside Bassenthwaite Lake. The main beams are laid out parallel and his routine is to put the rear beam in place, and then pull the trampoline along the tracks, with the front beam threaded through the sleeve at the front of the trampoline.

   A key point is that the ground should carefully chosen to be flat, so the main beams lie parallel in the vertical plane, as any “racking” distortion makes inserting (or removing) the bolts difficult. (The ground can slope somewhat, as long as it is a flat surface.) In the photo above, the near main beam appears not to be level with the far one---this is probably just a camera angle distortion, but if not, he will have difficulty getting all the bolts into place, at least needing to lift the far left and near right corners to juggle them in.

  Gareth, above, has a slightly different approach. He drops both cross beams into place (above left) and then pulls the tramp through, above right. (This is not a two-man job, but is slightly easier pulling directly along the tracks!) The frames are then bolted at each corner, below.)

catapult assembly
Left:  fastening the beams

The inner bolts  are fitted first at each of the four corners , and then the four outer bolts 

(The photo also shows the orientation of the front beam, with the cast alumium mast step facing aft towards the trampoline)


   Even at this early stage in the process, different helms have several different routines.

   Alastair leaves the two beams initially closer and roughly parallel, pulling the trampoline deck through the side channels still loose. (Photo below left)
He then puts the rear beam in one bracket, bolted in the inner channel, photo below right . When the free end is lifted slightly, this gives an  accurate fore and aft position for the other main beam. (The cross beam is very vulnerable while loose at the other end, but he has so far avoided kicking it or stumbling to wrench the fastenings)

  The forward beam is then threaded through the trampoline deck, put roughly in place, and the second main beam pulled out to the width set by the trampoline, so the cross beams can be dropped in.

( The mainsheet, forestay bridle, bolts bag and towrope are stored ready inside the folded tramp )

Right:  The line is tightened successively around the studs on the aft face of the rear cross-beam.

On this boat, the line finishes at a clam cleat, as a quick fastening.

The blue ball prevents the line from unwinding through the tramp bars.
 Lacing the tramp

NOTE: Pulling the trampoline as tight as possible will help keep the boat stiff. The line should be Dyneema (as it will not slacken at all when wet.) One thing to watch when tensioning the edges of the trampoline is that extreme tension may pull back the slots in the trampoline for the daggerboards so they do not quite align with the daggerboard arms.

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