Blisters in splash zone/boot top

[webcraft]

Cleaned the waterline from the dinghy today. The antifoul comes about 2" above the waterline. There is no boot top stripe.

Immediately above the a/f, in the splash zone, there was brown growth to a height on one to two inches above the a/f. When I cleaned it off there were small blisters all the way along.

Is this osmosis or something else? (The hull is painted, could be paint failure?)

- W

 

[Concerto]

It would be helpful to mention the type of boat you are talking about. Without seeing some photos of the problem it is a bit of guesswork.

Small blisters that are 2 to 3mm diameter are could be small air bubbles trapped in the gel coat from poor brushing out during application. However you mention the hull is painted, so it is likely moisture has got between the gel coat and paint due to poor preparation. It is highly unlikely to be osmosis.

 

[Kelpie]

Good chance it's just the paint. Can you squish them back down? Have you popped any? Osmosis has that distinct smell.