Yes..another question on hull blisters

[preserved_killick]

I'll start by saying that in spite of everything I've read on this site and through other sources with hours of searching and reading, I'd like some feedback before I do anything.

Here's my situation. I just stripped my hull of VC17 and found some craters from small blisters. There's lots of them, none larger than a half centimeter. They are all very shallow. Not bad on a 44 year old hull. At first I was concerned, now less so. I figure if this is all have in 44 years it should last a few more. Should I be?



Full size image: http://www.fongemie.com/boatbottom/boat-bottom-102.jpg





Full size: http://www.fongemie.com/boatbottom/boat-bottom-090.jpg


From reading every post in the Alberg 30 Association's email list archives I gather that Alberg 30s are not particularly prone to blisters, except for those who have added a barrier coat. There's a number of posts where a blister free hull had a "protective" barrier coat added only to have blisters appear a year later.

In my case, I wish I knew the history of this hull and why the blisters. At first I thought the grey layer between the hull and the gelcoat might have been a barrier coat, now I don't think so since it softens up quickly using SoyStrip. More likely a primer or tie coat I'm guessing. Was there ever a barrier coat? Definately some heavy sanding has taken place.

Here's my plan: leave it alone. I'll finish getting all the old VC17 off, then put on anti-fouling paint. See what I get when I haul out in the fall. I may try to fair out some of the craters, but I may not. They are so shallow that I any fairing would be for my peace of mind with this boat.

There is one section that might deserve some attention, and the area was sanded trough the gelcoat to bare fiberglass.



Does bare fiberglass need to be covered? I'll trowel on some epoxy/low-density filler mix before painting. Note that there does not appear to be a skinout mat of chopped glass, just a first layer of cloth. Perhaps that might contribute to A30s not having major blister problems.
I also believe that the blisters I see are small because they are limited to just under the gelcoat, and don't go deeper into the fiberglass cloth since there is less chance for voids.

Does this sound ok? I've never had a boat with any blisters before so my first reaction was to sand to bare gelcoat and epoxy the heck out of it. After researching the issue, that may do nothing to help..it might even cause more problems.

I'm open to any and all opinions on this. My knowledge on the matter spans one week of reading.

This photo is added because I just like the curves:

http://www.fongemie.com/boatbottom/boat-bottom-119.jpg

Jeff

[Tim]

Those aren't really blisters, at least not in the sense that everyone worries about. Hydraulic blistering is the result of a chemical reaction between uncured styrene, a major component of polyester resin, and the minerals found in salt water.

What you have there are areas where, over the years, the gelcoat has formed small bubbles (I am not going to call them blisters lest this cause confusion) where water has been trapped, often beneath layers of bottom paint and/or, in your case, that gray layer.

This happens for many reasons, but the mechanism behind what you are seeing is not the same as that which causes true blisters. You have gelcoat "failure" as it were (and it's not, but for lack of a better term...), not hydraulic blisters.

Nearly all boats the age of yours have these sorts of minor gelcoat interruptions. As with yours, these seem to be most prone to formation in the keel area and deadwood. I had the same thing.

Here's my plan: leave it alone...

A good plan. Go with it.

I've never had a boat with any blisters...

You still don't. Carry on.

[preserved_killick]

Thanks Tim.

Very glad to have your opinion.

-jeff