Blister questions

[Bad Obsession]

Last year I discovered a blister just after I bought the boat. The boat didn't have a blister that was visible during survey, but I discovered one once the boat was moved to an area in the yard so that I could do some work on the boat (bottom paint). The blister was where the jackstand was when the boat was being surveyed (I do kind of wonder about that particular placing of the jackstand). I asked the yard about the blister (it is about the size of a normal watch face). The yard said that I shouldn't worry about it, it isn't a big deal, and that most boats have or will have blisters. They said to bottom paint over it and not worry about it. That was what I did. I am going to haul out in early spring and that makes me wonder if I should grind it out and patch it or just paint it again.When I looked at the blister last year I tried to chip at it a little. It seemed that it wasn't too deep but it wasn't soft either. It was a circular place and a little water was seeping from it for a little while and then it stopped.Any suggestions or thoughts are welcome!

 

[droopy]

You got it right

grind, clean, let dry, then fill and expoy paint.

 

[Fred]

Grind but don't worry

One blister is nothing to worry about. When you grind it, don't get too carried away. A heat gun or small heater with fan on a barrel or whatever to get it to the right height (not too close. A fire is something to worry about) will help get it dry. Any epoxy resin or filler will seal it up, then fair with epoxy (maybe resin and micro baloons) sand, and bottom paint.

 

[Ross]

If I properly understand "boat blisters" they

affect the gel coat /glass matrix interface. If this is the case then removing the gelcoat blister by grinding and filling the "pothole" with filled epoxy and fairing the repair solves the problem until the next blister or swarm of blisters appears. I also understand (I think) that blisters are caused by water getting under the gelcoat and causing some swelling and thus the blister.I think that it follows then that an epoxy barrier coat will prevent the formation of gelcoat blisters and would be suggested as a first coat in preparing a new boat for antifouling paint. It might also be indicated for older boats with blister problems.

 

[Sandy Stone]

One other thing

The liquid trapped in a blister can be under a surprising amount of pressure, and it is something you really don't want to get in your eyes. So just be careful popping those blisters.My boat is out of the water now for a bottom job, and I ground out and filled several dozen blisters just as described below. Not a problem at all.

 

[Tom Spohn]

How Long

was the boat out of the water when it was surveyed? Reason for asking is that sometimes when a boat has been out of the water a long time the blisters dry out! The jack stand may have prevented the blister underneath from drying. If the boat had been out of the water a long time I would do nothing now--just put her back in the water and pull her in the spring. Then you can more properly assess the damage. If one or two large (bigger than a nickel) blisters appear they can be individually ground, dried, epoxied and painted. If a rash of pimples are all over the boat the gell coat must be ground off, boat dried, epoxied, and painted. This is an expensive, and long time process.

 

[sailortonyb Allied Mis]

Gougeon Bros.

Gougeon Bros., the makers of West System Epoxy, have a small pamphlet on how to repair blisters. I highly recommend it. Not sure, but I think West Marine may sell that pamphlet.Most times the liquid in a blister is an orange-brown color with a distinct odor. There are several theories on what causes blisters but most remedies are the same. Its a fairly simple procedure. Grind Blister, wash down with fresh water regularly, let dry and patch up.

 

[MABell]

Check out their web site

It has a wealth of info - including the how-to manualhttp://www.westsystem.com/

 

[Alain Pascal]

blisters

About the liquid in the blister: someone mentionned it and it is true, be very careful when piercing it, the water/hunidity that went throught the gel coat actually reacts with the fiberglass and creates serious pressure and it is quite toxic.Was the pads covered with carpet? Often blisters appear in the area of the jackstand because the carpet or material on the pad retain the humidity againt the hull and that humidity penetrates the gel coat.You often see boats, when taken out of the drink, that are full of little blisters quite scary but they disapear within a week.I would be more worry of a multitude of little bliters than a few larger ones.Do grind and repair as suggested even if just so the moisture won't travel along the fiber cloth.All this said, no boats ever sank because of blisters so...If I can be so bold as to suggest, for lake water, VC tar and VC17 best stuff around.Cheers,a.