: Interesting! Have you considered just thin epoxy on the insides, to seal the
: moisture with very little extra weight?

That thought has occurred to me, yes. I need some laminating resin, and I'll give it a try. Also, I'm not sure there is much gain by glassing the inside of the core strips - it's the cap strips that give the structure most of it's strength.

: Yes. If you prefer thin cap strips, then a stronger (and a bit heavier) wood
: might well be just the ticket!

Or thin cap strips with a layer of glass...

I think I'll do four cores - one with all 1/4" strips and poly glue. One with 3/8" x 3/4" core strips, 1/4" cap strips, and poly glue. One with 7/8" x 3/8" core strips, 1/8" caps w/4oz glass inside the caps only - and one with 7/8 x 1/4" core strips, and 1/8" caps w/4oz...

I think that it's reasonable to assume that the blades themselves add roughly the same strength to the finished paddle, no matter what the core construction. Therfore, simlply putting the first 1/4" blade strips on should be a sufficient imitation of the 'core structure' including the strength that the blades add to it.

If I laid up these four cores, and set them up on a lever at the midpoint - representing an extended paddle brace, which commom sense tells me should put the most stress on a paddle - after all, I did break one that way once - then adding weight to the end until it fails oughta give me a reasonable indication of the relative strength of each technique, wouldnt you say? Especially if I made all four cores out of the same board - eliminating material differences.
Whats a good way to add weight? A bucket of water?