Fitting & Shaping the Polystyrene Core
Now came the messy part (I hated this part and was glad when it was finished) I had purchased blocks of polystyrene from the local builder’s merchant. I cut them roughly to size and fitted them to the deck with waterproof mastic

Once this was set you must start to cut the polystyrene to the shape of the hull. To do this I welded two tenon saw blades together and used metal shelving rod to produce a saw. The blade was at 90 deg to the handle so that it was possible to hold the handle while cutting a horizontal cut. Using the keel and the side of the deck as a reference I cut the blocks to shape. At this stage you have to have a either a very understanding wife or be extremely careful. I was extremely careful! The polystyrene goes into little balls which stick on everything and go everywhere. Get them in the house at your peril!

A tip for those whose wife may not understand the finer points of boat building. I kept a change of clothes in the garage so I could change out of the polystyrene covered ones before I went near the house.

As the polystyrene is weak it can sometimes break off especially as you get to the edge of a sheet. To fill the resultant holes I used expanding foam, the type you get in a spray can from hardware stores.

Once the foam was cut to shape (it took a long while to get it right) it is time to cut the hull sheets. It is easy to get the main part of the hull sheet to the correct shape as it is no more than an oblong sheet. Bending the bow sheet round was another matter. This was where I came up against the building frame being oblong. I had cut the sheets very roughly to shape and tried to bend them round the hull and keel. Unfortunately they fouled the building frame and I could not bend them round with out them being cut accurately to shape. I could not cut them accurately to shape with out bending them round the deck and keel. The only solution was to cut the building frame. The problem was the legs were on the corners!

Bonding the Hull Sheets