Building the walk through cockpit version of Harrigami.

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Week 2: Tuesday 10th - Friday 13th of December 2002

A frustrating start to the week with the materials still not arriving due to courier hassles. Timber arrived Tuesday so we started by scarfing both ends of all the planks using a jig on the bench saw. I decided to use a previously untried method of planking. I have built boats using the wet method (where all planks are prescarfed and edge glued in batches) and the dry method (where strips are screwed to the frames with a gap left between planks and thickened epoxy sqeegeed into the gaps after all planks layed). I have tended to favour the latter method because all taper cutting and screwing occurs without the hassles of glue getting onto tools and sawdust getting into the glue joints. You can also make final adjustments to any unfair frames, though this shouldn't be a problem with reputable designers. The disadvantage of the dry method is the use of more epoxy and filler thereby increasing the weight and expense (I suggest using the screws made for securing gyprock. They are sometimes called 'drywall' 'grabber' or 'bugleheads'. Drive them in using a cordless drill).

With this boat I wanted to try a combination of the two methods. We layed all the planks dry, leaving no gaps. This is a very quick and pleasant method and allows good accuracy as there are no concerns with glue. We then removed a number of planks, ran a line of Purbond polyurethane glue along the edge and replaced the next plank. Purbond polyurethane glue is far easier to use than epoxy as it is one part and come in a squeezy bottle. As the glue cures it foams slightly filling any gaps left behind between the planks. We found that as one person screwed the plank back on the other followed with the glue ready for the next plank. This method would suit a loan builder.

Is it quicker than either of the traditional strip planking methods? I'd say pretty close and far less messy. Next time I would lay and glue all untapered planks first, then fit the tapered planks dry and remove and glue them using this method. The polyurethane glue is great with the proviso that it isn't used to fill too large a gap. Any large gaps we'll backfill with epoxy filler later when filling the screw holes.

It is best to glue only a small section at a time when strip planking as intermediate straps need to be screwed between the frames to bring the strips into alignment before the glue sets. These straps are made from cheap 6mm plywood cut across the face grain so they are flexible. They are plastic taped to prevent sticking.

Once all strip planking is glued and cured the straps and screws were removed and the surfaces sanded with a rotary sander. This can be a dusty process so try to use a sander with a vacuum attachment.

By Friday knock off we had strip planked, sanded, and backfilled the screw holes ready to glass on Monday.

Hours: 64 (total 99)

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