OK, so I'm Sanding My Bottom... - Page 5 - SailNet Community
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post #41 of 98 Old 04-23-2012
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Re: OK, so I'm Sanding My Bottom...

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Originally Posted by CapnBilll View Post
Regelcoating the whole bottom may not be what you want to do right now.
Don't EVER bother with that. If & when you decide to do the bottom properly, get it soda blasted or sand & scrape it down to a good surface, fill the blister divots properly with thickened epoxy, fair it up with orbitals and longboards then coat it with Interprotect per the manufacturers directions.

Presto changeo - a racing bottom!

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post #42 of 98 Old 04-23-2012
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Re: OK, so I'm Sanding My Bottom...

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I've had good luck with polyurathane, and with polyester. I would skp the bondo.
Bondo and other auto body fillers ARE polyester. They shouldn't be used on boats as they will permit water absorption - use epoxy fillers only.

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post #43 of 98 Old 04-23-2012
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Re: OK, so I'm Sanding My Bottom...

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Originally Posted by Sailormon6 View Post
If you'll look at the photo of the strainer, it is surrounded by white surface. I think that's your gelcoat. Everything on top of that surface is either old paint, or dirt or algae covered with old paint. I don't think most of the pits you are seeing are "boat pox." I think they are simply many layers of peeling paint. If you get all the red and brown and blue stuff off, eventually you'll get down to the white gelcoat, which is where you want to be. You don't want to remove the white gelcoat.

I wouldn't apply any filler to try to smooth it out, because I believe you'll be filling pits in old bottom paint and dirt, sealing them there forever. You have done a terrific amount of hard, nasty work, and smoothed out the original mess fairly well. My suggestion is that you apply one coat of ablative antifouling and enjoy sailing the boat for the summer, and then, next spring, have another go at it, and finish the job. After it's finally done, if you use no more than one coat of good quality ablative each year, you'll probably never have to strip it again. After you get rid of all that old paint, you'll be able to see whether there really are any osmotic blisters under it. At that time, you can decide whether you need to do anything about them.
Mon has it right - where there is bare glass showing, it is surrounded by white - almost certainly gelcoat. I would at least paint some epoxy resin over the bare glass that's showing before putting on bottom paint.

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post #44 of 98 Old 04-23-2012
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Re: OK, so I'm Sanding My Bottom...

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Bondo and other auto body fillers ARE polyester. They shouldn't be used on boats as they will permit water absorption - use epoxy fillers only.
SJB,

With respect, that's a pretty categorical condemnation of polyester fillers.

Like everything else, they have their place in the vast order of things. I'd agree that in almost every case, properly thickened epoxy is a superior product -- particularly below the waterline. For cosmetic repairs that are going to be top coated with a good paint, gelcoat or epoxy sealer, polyester fillers are fine (as well as quicker and less expensive).
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post #45 of 98 Old 04-23-2012
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Re: OK, so I'm Sanding My Bottom...

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Originally Posted by Squidd View Post
Exactly...

My goal is to fill, fair, put a sealer/barrier coat on and biocide paint...

See what it looks like next spring and "maybe" in a couple years a total redo...

But really it's a $3k boat...I'm not planning on putting $5k bottom job on it...
Totally agree. Good you got the old paint off, but I would epoxy her up now, paint her and get sailing.


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post #46 of 98 Old 04-23-2012
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Re: OK, so I'm Sanding My Bottom...

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SJB,With respect, that's a pretty categorical condemnation of polyester fillers.
Indeed it is - on boats. The only problem I've ever had with any filler on any of my boats was with a polyester glaze filler - used for pinholes and such - it failed in several cases.

I've used epoxy exclusively ever since. The cost difference is so minor in the quantities we're talking about that I don't regard any potential savings as worth the increased risk of "do-over" - especially when you figure the cost of quality topcoats.
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Re: OK, so I'm Sanding My Bottom...

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Indeed it is - on boats. The only problem I've ever had with any filler on any of my boats was with a polyester glaze filler - used for pinholes and such - it failed in several cases.

I've used epoxy exclusively ever since. The cost difference is so minor in the quantities we're talking about that I don't regard any potential savings as worth the increased risk of "do-over" - especially when you figure the cost of quality topcoats.
Like I said, epoxy is almost always a superior solution but at times it's overkill.

Sorry about your experience with the glazing putty -- I've been there myself (but only with cars, not boats.) The only thing I've used glazing putty for related to the boat is when making plugs/molds for fiberglass projects.
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post #48 of 98 Old 04-23-2012
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Re: OK, so I'm Sanding My Bottom...

I know everyone is just trying to be helpful which is what makes this a great place. I know that Squid has done a lot of research on this and actually read these articles on blister repair (posted earlier): Hull Blisters on Boats and Yachts - by David Pascoe, Marine Surveyor
and: Sea Lake Yacht Sales (Kemah, TX) (posted by Brian/Mitiempo)
written by surveyors with quite a bit of experience in hull blisters.
If you guys and gals read the articles you will find that neither surveyor has a high degree of confidence in conventional blister repair techniques recommended by most boat yards. Can any of you say that you have heard of, seen, or experienced a blister repair job that was effective and lasting, whatever the method?

Squiddo is in Wisconsin and wants to sail his boat this summer during the short sailing season. I can't blame him. Given the likelyhood of eventual failure of the patches (no matter what method or materials) I'd be thinking of using the cheapest, quickest method (polyester) to fair the bottom and go sailing - hoping the patches last a year or two before needing to be readdressed.

I've seen it time and time again on my boat and on other boats in my yard. The owner diligently applies an epoxy patch to the keel or hull and in a few years that same patch needs to be redone. Faulty method you say? Perhaps, or perhaps that is just the way it is.
I hope I'm wrong as my friends Endeavor 32' got a case of the blisters after being left in the water in the Chesapeake for 5 years. One hundred twenty dime sized blisters in that thin laminate would make Squidd's hull look pretty good.
Anyone know of a sure fire method for fixing blisters? Anyone?
Didn't think so. Conventional wisdom is so... conventional.

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Re: OK, so I'm Sanding My Bottom...

So if the theories are correct, that the blisters are caused by unsaturated mat, is there anything to be said for applying penetrating epoxy (in the hope that it will penetrate and seal the mat better) before the thickened epoxy filler?

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post #50 of 98 Old 04-23-2012
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Re: OK, so I'm Sanding My Bottom...

Blisters are not caused by unsaturated mat. The mat looks unsaturated after osmotic wicking has destroyed the resin that used to be in the fiber. Caleb - we have a couple boats that were done in the early 80's and still look great. Does that count?
If EVERY step is done correctly, a proper blister job will last decades. EVERY SINGLE STEP!
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