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| H18 Hull construction http://www.hobie.com/au/en/forums/viewtopic.php?f=20&t=9431 |
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| Author: | Adrio [ Sun May 18, 2008 8:24 pm ] |
| Post subject: | H18 Hull construction |
I was reading up on how to repair composite structures and one of the things they seem to say is to use the same material as the original construction (same number, weight and types of cloth, same type of resin etc.) To that end does anyone know how many layers and of what type (as in woven of mat etc.) and weight were used in the Hobie 18 hull. I guess there are different numbers and types on the outside of the foam, the inside of the foam and the none foam area on the bottom. Also what type of resin was used, was it polyester or vinyl ester or epoxy resin? And lastly, what type of foam was it? Sorry for the verbose post and long list of questions, but I would like to ensure my repair is done right. Thanks in advance, Adrio |
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| Author: | Rick Buchanan [ Mon May 19, 2008 9:23 am ] |
| Post subject: | |
Adrio, Yes, you should use the same type materials, but there can be an exception to this depending on the repair being made. Vinylester resin is a high grade polyester resin. It was recommended to me years ago when I was doing repairs to our Police boats in Oceanside....Yeah, I was a Harbor cop in my past life. The recommendation to use vinylester came from Crystaliner boat company (they made our $300,000. boats). This resin is a bit thinner than a regular boat yard type and flows out into the fabric quicker. As for the foam the factory uses, it's 3/8" thick Divinicell, and is PVC based. The factory used both a Matt type glass along with cloth similar to an 8oz weight. However, depending on what type of fix you're going to do you may want to use something different. For small dings, and holes 2oz Matt might be the best choice, but if it's a big hole like the one in the past HOTLINE article you may find a Dual Bias works better. |
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| Author: | Sail Revolution [ Mon May 19, 2008 11:05 am ] |
| Post subject: | |
Epoxy and Hobies. Rick's right about the Vinylester (as always;). Vinylester actually approaches the adhesion properties seen with Epoxy resin. So, on repairs like the one Rick so beautifully illustrated in the Hotline where he 'adhered' green glass to existing fully cured glass, Vinylester is a great choice. It's less expensive than epoxy, and there is less chance of having problems curing gelcoat over top. I always hotcoat (thick layer of gel placed over curing resin) the first layer of gel to make sure there is a good chemical bond, then for the topcoat add Duratec clear additive. By using a hotcoat between the fresh repair and finish gelcoat, you greatly reduce the possibility of pinair (tiny pin sized holes in the fresh gelcoat). Pinair will allow water to seep into the fresh glass and into the foam. If epoxy is used as a substrate under gel you are relying on basically a mechanical bond between the epoxy and gel, and the inner layers of gel may not cure. I think the reason people use epoxy is that the popular West Systems brand is well marketed and comes in easy to use pumps, so it's easy for the garage repairman to use. At over double the price, and possible adverse chemical reactions with polyester products, it's definitely not the best choice for Hobie repairs...other than delam. |
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| Author: | Adrio [ Mon May 19, 2008 2:56 pm ] |
| Post subject: | |
Thanks for the replies. Just for your information I am looking at a (three or four actually) repair similar to the one in the Hobie Hotline. our record snow fall this year was too much for the boat (and the trailer) even with me shoveling several times over the winter. We had a total close to 4 meters and one late storm (very wet and heavy) of 35cm or so. I think that is the one that did the poor boat in. |
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