Returned home to take advantage of cover, routing table, and band-saw etc. The cardboard templates have been used to make more robust templates on thin plywood. Shown below is the larger template along with a sample of end grain balsa. This being the challenge not mentioned in the books that end grain balsa does not support its-self and simply folds over as the picture shows. Of course this is not a problem when working with gravity on a mould, but upside down this could be tricky.
Plan B, a layer of 450g chop strand mat (CMS) was glassed to the surface of a piece of balsa larger that the plywood template, which seems to have given it some support whilst retaining the ability to flex.
Ultimately there is to be two circular marine ply pads inserted into the balsa, so that the pads on the stainless steel poles clamp onto solid ply and not balsa – this potentially being an improvement to when the boat was new. If these could simply be circular pieces of ply then this wold be straight forward, however, as the experts out there will know you should not create hard edges against fibreglass or it may stress and crack – not good. So the edge of the ply needs to be chamfered, and with that of course so does the balsa into which it is inserted. The dust cover from the routing table has been removed and setup.
Whilst tempting to do this from the cardboard template, some thought will be given as to whether to do a final fit on the plywood template and check the locating holes etc. This will also give a chance to do a dummy run on setting up a vacuum to hold it all in place – who in their right mind would do their first vacuum layup – upside down – needs must. Yes the initial layer of CSM could have been done as a vacuum layup on the balsa but that might / would have forced the resin into the kerfs in the balsa which would have made it solid.