16.5 ft tunnel hull

Cedar strips are easy enough to mechanically fasten or glue into place. What's the issue? There are two basic approaches, one is to glue and/or screw to a stringer system, the other is to glue and/or screw to a solid substrate (plywood). Both have advantages and disadvantages to consider.

The big issue is weight. Hydro don't like extra weight, especially that high up on the hull. If looking for a particular aesthetic, consider some form of faux wood finish, for the least weight penalty. If you don't care about the weight, then it can be done anyway you want, but strips over stringers will likely be lighter, if more prone to leaking than strips over a substrate.

The attached photo shows teak planking with mahogany covering boards. The mahogany was about .1" thick and the teak about half of this, both glued to a 1/4" plywood substrate. This weighed a lot more than just paint, but the design could tolerate the additional weight.

Maybe you should consider the teak and holly stripped plywood that's available, killing two birds with the same stone.

 

I really appreciate your advise ! I think I might just glue thin strips over the plywood but the extra weight does worry me. Possibly I will like the look of the plywood and be less concerned about the added weight of any extra beef I add in the structure.

 

those gielser boats do not have a glass covering and I know they don't leak.

 

the real issue is making it bigger. I want to make it 2 feet longer and probably wider and taller and its gonna be fun to figure all that out! I wonder what would happen if I changed tunnel height by a little one way or the other?