Thanks Wes and Sodbuster; your comments are much appreciated.

I am playing with a method of eliminating the taped butt joints by using splines which of course make the surface a little smoother. I am using 1/16" plywood as the splines. I have a router table setup and am running tests right now to determine the relative strength of sample pieces, including the taped both sides, and one side varieties. I am comparing them against of "solid plywood" to see how well they fare. The splines certainly work well and the process is manageable with a jig I created. The setup takes about 1 minute to position the wood and about 30 secs to cut. The gluing (another area I am investigating) takes about 4 mins then the usual clamping of course. I am unlikely to start the building of my Pinguino till spring so I have the time to try some ideas on scrap material.

I felt that as Wes says, the majority of the strength comes from the cloth sheathing on both sides, but wondered if I was missing something. I suspect the "tied together" nature of the whole structure (monocoque-like?) also helps.

For those who feel I am being a masochist, you are probably right but the challenge was too tempting having read about Tom Jordin's Spline Joint on Ted Henry's web pages! I will share the results for those who are interested.

Geoff