Join Date: Feb 2010
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Originally Posted by 75R20
OK, I searched and found very little to help.
While diving on my boat swimming, and scrubing the hull, I believe I found some blistering on the hull. They appear to be ~ 1/4" in size and not uniform in placement or numbers. Questions.....
Why/What causes this ?
Is it serious ?
Should it be repaired ?
The boat was built in 1975, and has been in the water at a moorage in fresh water for ~ 8 months. It has been trailered most all of it life, and is a fresh water boat, seeing salt for only a week or two at a time. Hull/boat is in excellant condition, buffed, polished, and waxed.
The boat is in the Seattle area.
Tiny blisters like that are often just paint
blisters. Try pushing on them with your fingernail; if they "give" then they aren't in the gel coat. Not much to worry about. But, if they are just paint
blisters, part or all of the problem could be an incompatibility between new and older layers of bottom paint
. You may need to strip off all the old paint
the next time you do a bottom job.
If you start seeing larger blisters that feel as hard as the surrounding surface, then they are probably in the gel coat and MAY need to be addressed at some point. In any case, the cause is osmotic pressure from the water trying to migrate under the paint, or into the fiberglass. It's a little complicated (and its not completely understood why some boats are more prone to the problem than others), but you should be able to find lots of info on the internet if you search for "osmotic blisters fiberglass".