Craig Olson wrote: > Michael J Edelman wrote: > > SNIP > > Given a hypothetical kayak of 10 ft^3 volume, we could get 64 lbs of ballast > > from 0.133 ft^3 of water or .012 ft^3 of lead. Assuming the rest of the space > > is air filled, the boat has the same displacement in either case, but a greater > > resistance to heeling with the lead. > > Your points are well taken. One little thing, though. You'd need 1.0 ft^3 of water > to get 62.4 lbs. of ballast. (0.133 is one divided by 7.48, the number of gallons > per cubic foot) The same ballast using lead would require about 0.13 ft^3. - i.e. > One ft^3 of water weighs 62.4 lbs. and 1 ft^3 of lead weighs about 490 lbs. Lead > probably weighs a good bit more than this, since the 490 figure is for steel. (My > book didn't list the weight of lead.) Whoops. Right. I had a beer with lunch. But the relationships hold. The specific gravity of lead is 11.43, I think. > Let's say we wanted 62.4 lbs. of ballast. Then we'd need 0.13 ft^3 of lead, which > could fit in a 6" diameter by 7.8" long tube strapped to the inside centerline of > the hull. Or - we'd need 7.5 gallons of water strapped down somewhere. A cubic > foot of water (or anything for that matter) takes up a lot of space! > > Having said all that, I agree that for most applications, the time needed to > assemble and install the ballast system might be better spent working on paddling > skills - braces & rolls - although that extra 50 FT-LBS. or so of righting-heel > torque could be very helpful to a roll in rough water. Of course, those of us who use folding kayaks don't really know how to roll- since we never have to. ;-) But I do recall Derek Hutchinson writing how he used a lead filled tube to add ballast for photography from the boat. Even the experts use it! -- ---------------------------------------- Michael J Edelman mje_at_mich.com http://www.mich.com/~mje http://www.mich.com/~mje/kayak.html http://www.mich.com/~mje/scope.html *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net ***************************************************************************Received on Fri Feb 13 1998 - 15:33:17 PST
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