Bulge on Keel

[David Digby]

My 1978 23' O'Day has two tennis ball sized bulges on the starboard side of the (fixed) keel. When I ground them down I saw shiny lead, surrounded by some fiberglass patching that was done professionally last year. I don't understand what's caused the bulges nor how serious this is. Does anyone have advice?

Thanks.

 

[HukilauMike]

Did the bulges have liquid in them? I've never seen them that big, but it sounds like osmotic blisters. Basically, water gets beneath the surface of the fiberglass, and "rots" the material. There is lots of detailed advice available on the net to deal with the nasty little buggers.

 

[kpgraci]

Right, liquid fillled (under pressure, wear eye protection when opening them) is the much discussed boat pox. If they came about by some other means, I guess it really doesn't matter (barring some structural cause), fix is the same, basically grind down, dry out, and patch using the correct material and technique. I fixed a few small ones and a large tennis ball size one on my boat - I've still got 30 or so small ones scattered across the bottom that I deemed no danger. On the keel I would repair them and put on a fresh coat of bottom paint.

 

[Barnacle Bill]

Bulges are not blisters and probably somehow moisture got in between the lead keel and the fairing compound which made it bulge - especially if you sail in an area where it can expand from freezing. The fix is to grind it all out, prime the lead, and apply epoxy fairing compound designed for underwater use. Fair it out and then apply your barrier coat and then bottom paint. If you find, after you grind down to lead, that there are holes in the lead or rust looking spots, you might have a lead keel that has imperfections in it. When lead is poured, there are non lead matrix that needs to be skimmed off and eliminated. If that has not been done and they were mixed in the lead, then you will not have clean lead, which will be spots where moisture can accumulate, etc. and so this could be the source of the problem too.

 

[David Digby]

Thanks everyone, for the good advice. I carefully ground down the bulges - shiny lead was inside, surrounded by some intact fiberglass patch work professionally done a couple of years ago. But the aft edge of the keel shows some delamination so I have ground and cut out the rotten stuff and am waiting for my friend who is expert in fiberglass to do the repairs -- then bottom paint -- and, hopefully, to the lake!