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PostPosted: Tue Apr 22, 2014 2:15 pm 
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Joined: Tue Apr 22, 2014 1:13 pm
Posts: 3
Hello!

I recently bought a '77 Hobie 16. It has a couple of "soft spots" and a large crack in the gel coat near the forward pylon. I read a lot of the DIY discussions here and watched the awesome YouTube videos from Any at BoatWorks Today and I'm confident enough that I think I know what I'm doing :)

I started by sanding away the gel coat and damaged glass around the crack and it turned out that the entire inner fiberglass layer had separated from the foam and had gone soft. It could be pushed in by almost an inch. I removed the entire top layer (leaving an inch and a half to re-glass the outside later on), and all the foam to reinforce the inside layer by layering up the inside with new glass (using vinylester resin).

I'm trying to find the right balance between stiffness, weight, and leaving enough space for the foam layer (I'm planning on pouring in foam to fill all the gaps).
So far I've applied 2 layers of fiberglass and it's becoming nice and stiff but I can still push it in a little bit. The question is how stiff should it be? Should there be some flexibility or is it better to have a hard surface to prevent future delamination?

Thanks for your help!


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PostPosted: Thu Apr 24, 2014 11:37 am 
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Joined: Mon May 09, 2005 10:25 am
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Location: Jersey Shore
You should try to match the original construction as closely as possible - i.e. match the skin thickness that was originally there. You don't want to make one area a lot stiffer or softer than the surrounding areas or this can lead to cracks. A single skin of fiberglass will not be very stiff. It only gains stiffness when it is built up into a sandwich construction with the foam core and outer fiberglass skin.

Also, when you mention that there is cracking around the front pylon, the first thing that comes to mind is that your pylon shoe has broken free from the hull. Repairing this would require access to the inside of the hull (generally done through a port hole).

sm


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PostPosted: Fri Apr 25, 2014 12:15 pm 
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Joined: Sat Apr 14, 2012 1:38 am
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Great videos. What foam do you plan on using? I have a hull that needs something like this and I was thinking of just trying to reuse the foam as much as possible on on the assumption that the problem is mostly delamination between the foam and the glass. Now that I think about this though, I suspect that once I get in there I will find the foam is decayed and not usable, so being able to pour new foam may be key.


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PostPosted: Fri Apr 25, 2014 1:45 pm 
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Joined: Tue Apr 22, 2014 1:13 pm
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@SRM, thank you for your response. The inner layer was too soft and would have delaminated immediately so I do think it was necessary to stiffen / thicken it bit. But I will follow your advice and just stick to 2 layers of fiberglass matting.

I was worried that the pylon shoe had broken free but luckily that wasn't the case. It had just pulled the inner fiberglass layer away from the foam. I think that by strengthening the inside layer that I've prevented that from happening again as much as possible.

@KarlR, I ordered a 2 part closed cell polyurethane foam from fiberlay.com. I'm planning on pouring it in 1 of the hulls this weekend to see how it goes. I don't think it'll be that difficult. Andy from Boatworks Today posted a great video series on the subject (http://boatworkstoday.com/archives/1546).


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