Join Date: Mar 2010
Location: SF - South Bay
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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.
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.
Last edited by paul323; 08-09-2013 at 07:00 PM.