Protruding Building Forms

[mick_allen]

As a typical kayak narrows toward its ends, when drawing up the building formwork the thickness of the forms doesn't work against you if you make the form thicker toward the wider part of the vessel. I've noticed that this doesn't always work - and was especially obvious in the 'sealpup' I showed a while ago. And it also showed up fairly significantly on this newer one also.
Something to keep aware of if there's sharp curvature - the 'wider' vessel parts aren't always wider in the same place! One fix is to slant the forms to follow the vessel's shape, another is to relieve the protruding parts of the form to the correct angle and another is to have one form part to the front plane and the other part matching the back plane of where the form face lies with respect to the shape.

It didn't concern me too much with 'sealpup' [mostly a thought experiment, tho' I'll make a half sizer] and most others [as it's a minor issue], but on this one I've had to make the adjustments [upper formpart uses back face plane, lower formpart uses frontface plane.

 

[JohnAbercrombie]

You are really venturing out to the edge of kayak design there!
Normal rules and methods no longer apply!

Looks like a cross between surfski and Ursa 420?

 

[mick_allen]

They're called 'waveskis'.
Typically quite high performace around 7'-6" long, this S&G approach is a slightly more quiet version for easier surfing at 9'-0" long. They use thigh or lap belts and can be rolled, but also mounted from the side if one is in the chuck.