CP. IF as I divine you are entertaining this cabin for either or your hulls, I would simply go by eye, or, as I do, get some card and a hot glue gun and make a cabin. The hot glue gun is great for this sort of thing, and enables you to cut`n`shut until you end up with a cabin the sort of size you are comfortable with. Also, a couple of figures on the boat always looks nice, and this may influence the size of superstructure, ie figure availability. Ash
PS Just possibly may have the new boat out on Sunday, so you can see how fast yours needs to be to beat me !!