: Porter

What is the reason for a specific length such as 23ft.? In my limited experience if one was to look for a general design but modify one element of a standard design you will be working against a whole the designer was working towards.

Nick would be the one to answer about his fast double. As far as stretching a ch180 I think you would be best off designing from the ground up as the modifications wouldn't address the buoyancy in the bow given the momentum of 400lbs and 23ft driving forward in a straight keeled (no rocker) kayak.