The hull shell for first of my V16 pedal boat variant has been produced in a female mould by a builder in Maine. The shape was generated using the 32 parameter shape function in Michlet resulting in variable flare and a small transom. Previous variants were generated with the 7 parameter shape function. There is about 3% reduction in drag using more shape parameters.
This hull will displace about 120kg with heavy pilot and is optimised for power input of 120W. It is 6.4m long. The trimmed shell, ready for bulkheads and deck panels is 6kg. This is a good start to producing a completed boat weighing less than 20kg.
He built a simple female mould from melamine coated compressed timber board. The hull shell was layed up in a single stage and vacuum bagged. It is not infused as this would have been riskier particularly for a first time builder. The melamine had no additional coating than release agent, which enabled the shell to be removed with a little encouragement.
Linked photos show the standard of finish and there is also a photo of the shell upside down on the mould to give some proportions:
The weight saving over normal flat panel comes in avoiding the chine seam as well as the high standard of surface finish almost eliminating fairing.
In terms of time - the time taken to make the mould out of a gently curved keel board with two hull sides attached is considerably less than making flat panels, cutting, mounting on strongback, joining then fairing. The 3mm thick foam used is easily cut with scissors. Thicker foam for larger hulls may take a more powerful tool but still trivial compared with cutting pre-glassed panel.
The value of flat panels is that the mould becomes a trivial item in the project but still results in a good finish, weight saving and fast layup. Seems a shame to only make one hull from it but it is not expensive.
Although the builder is new to glass/foam composites he is an experienced craftsman with wood as his workshop suggests.
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