Are these blisters, cracks, or what? - SailNet Community

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Old 08-09-2013
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Are these blisters, cracks, or what?

I have a 1970 Contest 30. It's been sitting on a trailer for a long time. Recently I noticed some cracks and discoloration on one side of the hull. I am trying to figure out if these are blisters, cracks, or what. The boat has an encapsulated ballast keel. There is a deep bilge about where the cracks are. The bilge is dry, even after severe rain, which makes me suspect that rainwater has been getting into (and through) the fiberglass out from the bilge. Any help and advice appreciated. I am trying to sell the boat, and I don't want the next owner to sink with it.

-R
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Old 08-09-2013
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Re: Are these blisters, cracks, or what?

Only way to find out is to open up that area with a grinder. If it is wet inside then it will have to dry out before it can be re-sealed. Wet material may have to be removed and replaced. I would find a good surveyor to look at it. No way for anyone here to give you a definitive answer.
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Old 08-09-2013
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Re: Are these blisters, cracks, or what?

It doesn't look like blisters to me.
There definitely has been moisture weeping out of those crack(s) though.
This is something I'd want to have fixed before trying to re-float that boat.

Tim R.'s repair advice is spot on.
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Old 08-09-2013
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Re: Are these blisters, cracks, or what?

The thing that concerns me is the coloring. Looks like corrosion of metal but that doesn't make sense. What could be near enough to the surface to corrode like that? What is the ballast?
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Old 08-09-2013
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Re: Are these blisters, cracks, or what?

So my best guess would be water penetration between the ballast and the fibreglass, leading to corrosion between the two and thus forcing the fibreglass layer outwards, leading to cracks.

That is just a guess, though.
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Re: Are these blisters, cracks, or what?

Ballast probably contains pig iron or similar.
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Old 08-09-2013
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Re: Are these blisters, cracks, or what?

Certainly looks like cracks in the fiberglass encapsulating the keel. If the ballast is iron (which is likely) you have a big problem. As the iron rusts, it expands and that can cause major damage.
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Old 08-09-2013
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Re: Are these blisters, cracks, or what?

IMHO, unlikely to be blisters.

TimR gives good advice,

I am not familiar with the layup of your boat, but many boats with encapsulated ballast also have a "false keel", generally astern, to increase the keel size beyond that of the ballast alone. Builders often put all sorts of junk in the false keep to help fill the void without using expensive epoxy. (I pulled out milk jugs in a previous boat). Sometimes the false keel voids then fill up with bilgewater, which can't escape, and so works its way out through the keel. Often it can react with the epoxy becoming highly acidic, making matters worse.

So:
Best case: False keel cr*p. Grind, let drain, fill properly, check /repaint bilge.

Bad case: Water has penetrated around the ballast in the encapsulated keel, rotting the 'glass (yes, glass cloth not fully whetted out with epoxy can rot) possibly loosening the ballast within the keel. I have heard - but not tried: Drill holes, drain, try injecting epoxy, maybe acetone first to really dry/clean things - keep fingers crossed.

Worse case: Penetration to a cast iron ballast. Corrosion of ballast. Cast iron does not rust much, but given enough time a saltwater it will rust and expand, potentially cracking open the glass encapsulating it. Let's just hope it isn't that.

Good luck!

Last edited by paul323; 08-09-2013 at 06:00 PM. Reason: typos
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Old 08-09-2013
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Re: Are these blisters, cracks, or what?

Glass cannot rot.
An epoxy hull is extremely rare. Contest 30's were built using polyester resin not epoxy. You will only find epoxy hulls in very high end boats.
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Old 08-09-2013
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Re: Are these blisters, cracks, or what?

Looks like a core of boiler punchings. Cutting out a panel of the glass will tell how bad it is. On wooden boats with internal ballast poured in concrete the iron chunks swell with rust, forcing the planking and requiring a whole bunch of nasty hammer and chisel activity.
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