: Those are all good ideas Paul, thanks. You really think it'll be 4,5 or 600#?
: I'll need a way to fill a 35 gallon drum with sand... This will be
: interesting...

Instead of a big drum, maybe fill some sandbags and preweigh them. Try to make them all 25 pounds for instance. When they fall they won't even bounce, and probably won't spill. No dents in the floor, either. What about a 2 foot square piece of 3/4 inch plywood held up with aircraft cable running from the corners? This would give you a platform you could pile sandbags on, and place a bucket in the center. If you fill the bucket, stop, weigh your platform, empty the sand from the bucket, add a sandbag with a little less weight than what you emptied from the bucket, and put the empty bucket back. Then go back to adding sand.

The local hardware store sells 45 to 80 pound tubes of sand for cars for traction in winter. (For those of your in warm climates who don't understand this, the sand is kept in the trunk to add weight over the rear wheels, to hopeflly allow better road contact in icy and wet road conditions. Should the car get stuck in snow or ice the bag of sand can be opened and the sand applied directly to the ice, giving added friction and traction. For those of you in REALLY nice climates, and who don't know what snow and ice are, but have plenty of sand -- can I come to your place next January?)

Consider: how strong is the 4 ounce glass you'll be putting on the bottom side of the paddle shaft? The glass on the tops doesn't matter, as it is jsut being folded by the pressure, but the glass fabric on the bottom has to stretch and rupture -- or the resin has to go -- before the shaft can bend enough for the wood to fracture.

Even after the wood crushes, your paddle is not necessarily going to fall apart. You would have to shear, break thru or stretch out the glass to have that happen. And THAT takes a lot of weight.

A one inch wide strip of nylon, or polypropylene webbing, such as used for holding on hatches, can take a load of hundreds of pounds before it breaks. Your epoxy-impregnated glass fabric is going to be less flexible than webbing, but probably stronger than nylon. Of course the manner you are testing applies your load in totally different directions, and you have to consider the leverage effect of longer or shorter lengths of the paddle shafts -- but I've seen some awfully big hockey players put all their weight, and momentum, on the end of a hockey stick --- and the blades are about the same thickness of wood, and fiberglass reinforced as your paddle shafts.

I think by extending the shaft fully, putting the maximum
: leverage onto the break point, that number will drop.

Put your moounting points as close to where the paddle blades would attach, and keep the length of your test shafts as sloe to what you would produce for a paddle. Then not only do you get some interesting data, but you get data that is directly related to what you are building. If you see that some 6 foot long test shaft breaks at 45 pounds, the answer is less meaningful than finding that your 3.75 foot paddle shaft won't break with over 200 pounds of force applied. With actual paddle shaft lengths you'll have numbers that you can later tie together with real-life situations (stresses exerted during rolls, for instance).

: Keep in mind, for
: this initial run I'm not interested in the actual breaking strength of a
: paddle. I am interested in the relative deflection / strengths of
: different core strip thicknesses and with or without glass.

Aw, come on. Sure you're interested in breaking strength

: If there is a clear winner, then I'll break some actual paddles. I already
: have two candidates, paddles with flaws that I dont think I'd sell to
: somebody. Theyre perfectly good paddles, and I thought about giving them
: away at R2K2, but I think this data will be more valuable in the long run.

Testing paddles that you know are flawed might be a waste of time, and confuse the limited data you've gathered. Unless you intend to produce paddles with the same "flaws" these would normally be rejected (or given away).

Test what you are best capable of making as that will become your only product. If you can make a strong and a weak paddle, who would buy the one that is more likely to break? Nobody wants the inferior stuff.

: I wish I had a video, that is a great idea, but unfortunately not...

Since you are on this board you have a computer. I've been getting "free" web cameras that plug into the computer from Office Depot or Office Max. These are uaually products that sell in the $40 or less range which have compound rebates that refund almost all your money. You still pay sales tax and postage on the rebate. The software with them allows you to make movies which are a bit jerky, but should be suitable for this. Move the camera in close and save the file on your hard drive. Edit out the boring stuff (endless pours of sand) to make a smaller file and reclaim some disk space. You may not have your video on tape, but every frame is a digital image ready to be uploaded. Select a few choice stills for us.

Just some thoughts

PGJ