The problem of shaping material to fit around the complex curves of a boat has many solutions.
Here is a way that is simple and quick and produces very accurate results. The only down side is that it is slightly wasteful of material.
The secret ingredient is a really neat and very inexpensive little tool – the hot glue gun. The glue gun melts the glue sticks and extrudes the melted glue from its nozzle. The extruded glue sets very quickly and is strong enough for this task.
The hot glue gun - a great tool for making templates
The other ingredient is some scrap strips of timber. At least one of the pieces has to be flexible enough and long enough to be bent around the curve to be templated without breaking.
Fortunately I have piles of thin strips of timber that are offcuts from straightening and sizing framing timber.
The trick is to bend a thin strip around the curve and hold it in shape with bracing and hot glue. Its a bit like the way the spokes of a bicycle wheel hold the rim in shape.
A finished template. Note the solid post at the left to brace against.
The bracing holds the strip in shape
Once you have enough bracing to be sure the timber strip is firmly held the whole assembly can be removed and laid out on ply or whatever to trace the shape.
Template laid out on ply to mark it for cutting
Finally cut out the ply and it should fit nicely as long as your cutting is accurate.
The cut out ply in place for checking
Its a reasonably close fit - good enough for this job
With the new sections made and fitted the bulkheads around the cockpit are slowly taking shape.
Aft bulkheads coming together