ralph diaz wrote: > > I like to add some comments to what Sandy Kramer discusses below and > also to followup on comments by Joan Spinner and Dave Gutierrez. > > 1. Those inflatable pads from Target would worry me based strictly on > the question of reliabliity of anything inflatable under lots of > pressure. While the payload seems OK at 80 kg, that is just laying > downt the weight on the inflatable pad. You really are going to add > more pressure in tying the boat down on to the inflatable pad. > Regardless, if the the inflatable pad fails, you are in trouble. Agreed the pads can puncture. How likely is that? Even if made of cheap vinyl, they probably can withstand the service pressure -- see below for my rationale. Assuming surface area of contact to the pads measures 3 inches by 10 inches on each pad (conservative estimates, I think), that makes a total of 60 sq inches to distribute the added load over. If you are really a buff brute, you might double the load by pulling extremely hard on the straps to make the kayak press harder on the pads. Suppose your kayak is a Doug Lloyd tank (80 lbs), and you double the load to 160 lbs. Now the miracle of division: 160 lbs / 60 sq inches = 2.7 lbs/sq inch That is a very small pressure increase (compare to atmospheric pressure of 14.7 lbs/sq inch and an ordinary tire pressure of 30-35 lbs/sq inch), not "lots of pressure." The actual pressure increase will be smaller yet, I suspect, probably close to less than a half of what I have calculated, because a typical single kayak weighs only 50-60 lbs, and pulling hard on the straps probably only increases the loading another 30-40 lbs, max. I would not worry about the pads failing unless someone purposely punctures them. -- Dave Kruger Astoria, OR *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************Received on Sat Dec 09 2000 - 23:07:42 PST
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