The boats that are being discussed belong to my wife and I. They were not a light lay-up, and acording to family members who sail for Stars & Stripes, America Cup etc. the color has little to do with the failure. The issue is probably a combination of a bad batch of resin, air tight hatches, and moving from 7500 ft. elevation to sea level plus the color and sun. The boats are Pintails and in my opinion the finest boats I have ever paddled. They make even the best boats I have paddled feel like bricks. They are not very heavy either. The Britts are just way ahead of the rest of the market, again my not so humble oppinion. When conditions get interesting these boats shine whether in storm surge in Sothern CA. on tide rips under the Golden Gate Bridge. GRO is standing 100 % behind the problem and are sending replacements. Good Hunting Lew *************************************************************************** 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/ ***************************************************************************
>...the color has little to do with the failure. The issue is >probably a combination of a bad batch of resin, air tight hatches, and moving >from 7500 ft. elevation to sea level plus the color and sun. Actually, the dark color (at least in part) helped. If moving the boats from 7500' to sea level really caused the problem, the color may have both helped and hurt. If you assume a 50 deg F (10 deg C, 283 deg K) temperature at altitude, the pressure difference relative to ambient (at sea level) varies between -7.3 psi (with no internal temperature change) to -4.1 psi (with an internal temperature of 120F = 49C = 322K). If heated up enough (to about 213F in this example) the pressure difference would be zero. Where the color may have hurt is in the strength of the hull. Does a fiberglass (or carbon fiber or kevlar) layup get weaker when heated to 100-120 degrees or so? I converted these pressures into feet of water to put it into a context to which most of us can relate: 7.3 psi == 16.5 feet of water, 4.1 == 9.4 feet of water. Brian Curtiss *************************************************************************** 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/ ***************************************************************************
I think that what Brian is saying is: the solar heating and positive pressure due thereto held off the "crumple" until the boat was placed in water and the interior pressure fell. This argument relies heavily on very good thermal conduction by hull resin, as the entire interior volume has to cool off to effect a great pressure change (irrespective of kayak cargo, not expected to shrink). Consider instead, that the resin itself is a very _poor_ thermal conductor, and thus shrank itself only in the bits that were immersed. Very like cutting a glass bottle by tying an alcohol-soaked string around it, lighting on fire, and dousing it in ice. Kevlar and fiberglass are actually pretty heat resistant (notice that your fireplace glass doors are very likely sealed with fiberglass, and that a bulletproof vest converts mechanical energy to thermal). So, resin is really the issue, as we could expect the fiberglass to actually act more like rebar inside concrete, spreading stress out over a greater area. In this scenario, parti-colored hulls (white underneath, black on top?), kayak loading (oops stressing the weak 'glass free resinous bit) all contribute to the failure. So: either the resin was weak with pinholes in it, or (restarting a tired hare) vacuumbagging is the true ticket to durability. P. Gudac Brian Curtiss <bc_at_asdi.com> wrote:>...the color has little to do with the failure. The issue is >probably a combination of a bad batch of resin, air tight hatches, and moving >from 7500 ft. elevation to sea level plus the color and sun. Actually, the dark color (at least in part) helped. If moving the boats from 7500' to sea level really caused the problem, the color may have both helped and hurt. If you assume a 50 deg F (10 deg C, 283 deg K) temperature at altitude, the pressure difference relative to ambient (at sea level) varies between -7.3 psi (with no internal temperature change) to -4.1 psi (with an internal temperature of 120F = 49C = 322K). If heated up enough (to about 213F in this example) the pressure difference would be zero. Where the color may have hurt is in the strength of the hull. Does a fiberglass (or carbon fiber or kevlar) layup get weaker when heated to 100-120 degrees or so? I converted these pressures into feet of water to put it into a context to which most of us can relate: 7.3 psi == 16.5 feet of water, 4.1 == 9.4 feet of water. Brian Curtiss --------------------------------- Do you Yahoo!? The New Yahoo! Search - Faster. Easier. Bingo. *************************************************************************** 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/ ***************************************************************************
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