Got a question: why are we all so surprised and so concerned that a solid rubber product which we stretch onto stiff flanges, leave out for extended periods in hot sunlight, and expose regularly to salt water --- for most of us --- shows some signs of surface checking or deterioration after a few years' use? We all buy rubber tires for our cars, and, in a few years, note that the tread is worn down, and that, if we haven't regularly used 303 or similar products on the sidewalls, see surface deterioration, but we're not up in arms with Mr. Firestone. I don't get it. How many of us have had failures with VCP hatches? If we were concerned about these things cracking and falling off, sure --- then we should grill VCP for lunch. But that's not what this thread seems to be saying. My Pintail is nine years old. It is garage-stored, but will frequently live on my roof for days or a week at a time during the busier bits of paddling season, summer and year 'round. The hatches are original. They've been pretty regularly maintained with 303 --- although I hadn't heard of having to take them off during non-use (but I do loosen them and leave them over but not attached to the flanges). Are they crazed and do they have some surface cracking? Sure. Do they keep the air in and the water out? Yup, as well as when they were new. Have they cracked or fallen off or failed at a critical time? Nope. Sorry to throw water on the hatch-fire, y'all, but I don't see where the problem is. Do these things age? Sure --- as do we all. But, until these things show some significant indication of potential or impending failure, I don't see where cosmetic cracking is a problem. Nine years, same hatches, occasional 303. If it ain't broke, why fix it? Jack Martin *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced/forwarded outside PaddleWise without author's permission Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
JCMARTIN43_at_aol.com wrote: > Got a question: why are we all so surprised and so concerned that a solid rubber product which we stretch onto stiff flanges, leave out for extended periods in hot sunlight, and expose regularly to salt water --- for most of us --- shows some signs of surface checking or deterioration after a few years' use? We all buy rubber tires for our cars, and, in a few years, note that the tread is worn down, and that, if we haven't regularly used 303 or similar products on the sidewalls, see surface deterioration, but we're not up in arms with Mr. Firestone. Yeah, but when my tires quit, they had each been pounded with one quarter the weight of my car for 65,000 km over seven years at 100 kph. They hadn't failed; I just didn't trust the amount of tread left. I think the two or three year life expectancy of hatch covers is pathetic. I can't imagine why they can't get a better material. Mike *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced/forwarded outside PaddleWise without author's permission Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
In a message dated 7/29/00 1:20:02 PM, michaeldaly_at_home.com writes: << I think the two or three year life expectancy of hatch covers is pathetic. I can't imagine why they can't get a better material. >> I second this opinion. Jed *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced/forwarded outside PaddleWise without author's permission Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Okay, MTBF on VCP hatches appears to be a couple or three years for those who have responded. Is there anybody else out there who has gotten a lot of years out of their hatches? Am I it? Jack *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced/forwarded outside PaddleWise without author's permission Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Ralph wrote: > I have an hypothesis on why the underside, in defiance of the logic that > the upperside would sustain the most exposure and UV damage, is reported > to be the side with the greatest tendency to show cracks according to > paddlers reporting on this issue. It has to do with the nature of the > flexing of the lid and how the two different planes (topside and bottom > side) are affected by the action of placing the lid over the hatch hole. <<snip the rest>> > This certainly sounds plausible, but consider: IF the hatches are made of natural rubber, a contributing factor may be the physical properties of the rubber itself. Caveats: I don't know if VCP hatches are made of natural rubber (rather than some other type of elastomer) and I don't have VCP hatches on my boat (so I have no personal experience with cracking VCP hatch covers) - but the chemist in me has an idea, supported by a bit of evidence. Encarta (http://encarta.msn.com/find/concise.asp?mod=1&ti=01307000&page=2) defines rubber's physical properties this way: "Pure crude rubber is a white or colorless hydrocarbon. The simplest unit of rubber is isoprene, which has the chemical formula C5H8. At the temperature of liquid air, which is about -195° C (about -319° F), crude rubber is a hard, transparent solid; from 0° to 10° C (32° to 50° F) it is brittle and opaque, and above 20° C (68° F) it becomes soft, resilient, and translucent. When rubber is mechanically kneaded, or is heated above 50° C (122° F), it becomes plastic and sticky; above 200° C (392° F) it decomposes. Crude rubber is insoluble in water, alkali, and weak acid; it is soluble in benzene, gasoline, chlorinated hydrocarbons, and carbon disulfide. It is oxidized readily by chemical oxidizing agents, and slowly by atmospheric oxygen." The key here is the last sentence, which states that natural rubber has poor solvent/chemical resistance. I'm suggesting that the chemical vapors from the *inside* of the boat are chemically weakening the rubber so that it may be more prone to cracking. Most of the respondents to this thread have stated that the cracking occurs on the *inside* of the hatch cover, which cannot be caused by UV radiation as UV cannot penetrate through an opaque hatch cover. Physical flexing is certainly a possiblilty, but one of natural rubber's *best* properties is its elasticity and resilience, which would indicate that repeated flexure should not be a problem. These two links compare the properties of natural rubber to those of other elastomers: http://www.sasindustries.com/serv01.htm http://www.tamparubber.com/mainprop.htm I pose these questions to those who have reported cracks in their hatch covers: 1. Do you routinely keep your hatch covers installed on the hatches? 2. If so, do you smell a resin/chemical smell inside your hatch when you first remove the hatch cover? 3. Is your boat relatively new? If the answer to these questions is yes, I'm suggesting that the chemical vapors that are generated by the resin and/or the catalyst used to make the boat are either chemically degrading the rubber to the point where it cracks, or are chemically degrading the rubber to the point where the flexural stresses as described by Ralph can cause the cracking of the inside of the hatch covers. The resins used in boatbuilding achieve much of their final strength quickly, but take a *long* time to achieve full and final cure - and generate chemical vapors in this slow curing process. My supporting evidence? Jack Martin wrote: > Okay, MTBF on VCP hatches appears to be a couple or three years for those > who have responded. Is there anybody else out there who has gotten a lot > of years out of their hatches? Am I it? > but in his prior email, he had written: > I do loosen them and leave them over but not attached to the flanges > Maybe the reason that Jack gets the additional life out of his hatch covers is the simple fact that he does not leave them attached to the hatches, thereby letting any accumulated chemical vapors inside the boat dissipate. And I'll bet that since he lets the inside of his hatches breathe, he also doesn't have a strong (or any?) resin smell inside his hatches (though older boats will have less of a resin smell to them). If any of this *might* be true, then the simple solution would be to store one's boat with the VCP hatch covers OFF the hatches - especially when the boat is new. Erik Sprenne a Great Lakes paddler *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced/forwarded outside PaddleWise without author's permission Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
In a message dated 7/31/00 5:12:00 AM !!!First Boot!!!, sprenne_at_netnitco.net writes: << If any of this *might* be true, then the simple solution would be to store one's boat with the VCP hatch covers OFF the hatches - especially when the boat is new. >> I store my British boat outdoors, in Florida, VCP hatch covers off. The hatch covers are almost three years old w/o a crack and have never been treated with 303 or any such product. The expansion and contraction of the hatch covers caused by the heating and cooling of the air inside the hull worried me. It may have been a contributing factor to the deterioration of the first set of hatch covers. Bruce McC WEO *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced/forwarded outside PaddleWise without author's permission Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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