: This may be tempting, but does one not need some thickness to get the oval
: final shape?

I looked at this in CADD yesterday. By adding the thickness into the core strips, 3/8" thick, there is still a 1/4" glue joint using 1/8" cap strips and a 3/4 diameter roundover bit. I dont want to experiment yet with smaller than a 1/4" glue joint, so none of the layups will be smaller than that.

: When you make test cores, always make them the same length. Also, get a
: little black book and write down all the dimensions and wood data, and
: results. Then you can add new tests years from now without needing to
: repeat anything you've already done before.

Given and given. Actually, Jeff has decided to use this as a school science project as well, so it will be pretty well documented. I was a little miffed because I need to write this test for my function, not his. The result is that i'll do my test, and he will build on it by testing actual paddles in different woods, based on the success of the initial core testing. His question is 'does the weight affect the strength', with no limitation on materials or structure. My question is 'what is the best strength/weight ratio for these given structure dimensions'.

This will be interesting....

: I'd assume that the loom is the weakest area, and just disregard any blade
: strips, since they will only add strength, some more, others less.

: I'd support the cores at each end, always the same distance apart, and hang a
: bucket at the middle, and slowly fill it until something happens. I'd make
: the distance greater than a typical loom length, then it would break
: sooner. That would also give a sort of guaranteed to survive value for the
: shorter loom on the actual paddle. This is in fact the same test you
: described, but easier to implement. Only the force pulls down instead of
: pushing up, just like in a C-to-C roll.

I think your model is a different animal - the breakage would have to occur twice - on either end of the load. By using an overhanging beam, the break will only be once - at the point of support in the middle. And by adding the first of the blade strips, I can be assured that the middle will be the weakest point in the structure - as is the case in an actual paddle anyway.

: You can also test for different materials, later on, by freezing the
: dimensions and structure instead. Both can be easily done. But not
: everything the first time you do this, naturally.

: I'd add sand or gravel or pebbles - the last would be the cleanest, no dust.
: Weigh the bucket and pebbles afterwards, or maybe also at intervals.

Buckshot, with luck Sand would be cheap and convenient. Thanks!