Evening Gordon....even with the planned hull at 22", I would avoid any form or thickness of plywood for hull planking
By the nature of its construction....eg., 3 ply...we have both outer layers with the grain in the horizontal plane & the inner layer with the grain in the vertical plane...which is great for mechanical strength but it does not want to bend in the 3rd plane ...and is a hard material
Cedar planking can be bent & twisted in two planes, steamed if needed, is a much softer material which can easily be sanded
This sandability has the advantage that it is easy to sand a chamfer on adjoining plank edges to ensure a good profile fit
So again even for a 22" hull, I would consider 1/8" thickness x 1/4' width cedar planking worthy of consideration for a good start
.... Derek
