Blisters: Are They Life Or Death?

[JiffyLube]

I know that all fiberglass hulls in the water long enough will get blisters, but depending on the size or quanity of them is it really necessary to repair them. One yard thought they should be repaired, and another yard thought repairing them just invited more the next year but in different places...and both yards are considered reputable.

What do you do?

[mitiempo]

Blisters that are just in the gelcoat are more like acne. Mostly cosmetic.

Blisters deep in the laminate are more like leprosy. These will make the laminate weaker. These need a thorough grinding and repair.

[PalmettoSailor]

Originally Posted by mitiempo

Blisters that are just in the gelcoat are more like acne. Mostly cosmetic.

Blisters deep in the laminate are more like leprosy. These will make the laminate weaker. These need a thorough grinding and repair.

I agree that the answer is "It depends". In all the posts regarding blisters I've ever read I've yet to hear of a boat being sunk or even put in peril by blisters. I have read of tons of money being spent to perform various sorts of repairs. So, I tend to believe blisters are more of a cosmetic issue than a real threat to the safety of the boat.

I do know that many, many, many boat sales have been sunk by blisters though, so if you want to sell the boat you need to fix them one way or the other and then find a buyer that believes your chosen fix is adequate. There are some that probably would not be satisfied with grinding a filling and would want a price concession towards a full peel, bottom rebuild and barrier coat.

[tommays]

On a cored hull with only 1/8" between the water and there a BIG deal

[SEMIJim]

Originally Posted by JiffyLube

... another yard thought repairing them just invited more the next year but in different places...

That makes no sense. I would be cautious of taking this yard's advice in the future. As to whether to repair them: That depends. We did. (And no: More did not appear elsewhere as a result .)

Jim

[Stillraining]

Actually it does heed advice and makes sense.

If not repaired properly and even if properly..repairing blisters opens up further edges of resin starved mat ( This is 99% the problem) for water osmosis to have access to at a future date.

I have blisters on my boat...I have repaired a couple but the tiney ones I just leave...All of them are in the reason starved mat used as a print through barrier for the gel coat fairness....The underlining roving and cloth is a translucent green and very shiny indication a stellar layup.

It is this cross section that is the culprit 99 % of the time...I could personally care less if that cross section of the hull bottom fell completely off my boat in one huge shed like a snake skin....Actually I would prefer that.as pealing a hull damages the roving in the process...Id take the opportunity to lay up another payer of roving and fair it with thickened epoxy for a much stronger hull cross section better suited for my needs.

Here is a picture of two I repaired....I didn't even bother fairing them back flush with the hull....Its an experiment to see what happens now at the edged of the repair..

I exposed back to solid mat ( as solid as there is ) and applied 2 coats of epoxy over the exposed roving as a barrier coat...slapped on two coats of bottom paint and called it good....If after a couple years in the water more do not appear around the edges I will fair them.

They were two of the three biggest blisters on my boat at 1/2 dollar size...all the other are nickel size of smaller....they are about 3 or 4"each now to get back to good mat.

CSM has little if any structural function on our boats ...it is used as a filler and or like i said a fairing layer nothing more...I have personally yet to see roving on any boat affected with blisters...saying roving NEEDS CSM for blister protection is just plain heresy.

There are many old boats that have roving as their only skin with a faring compound used to hide the roving s pattern...These boats seldom if ever incur any blisters of any kind.

[JiffyLube]

I don't plan on selling out boat, so I'm not concerned about addressing any blisters for that purpose...It's really for my own edification. I guess what should be done is to open all the blisters up, to see if they are in the gel coat or deeper. So what do you think...Fix the deep ones and leave the gel coat ones?

[Stillraining]

Gel coat blisters are not the same as osmotic blisters and are due to other issues...they can be found on topsides as well ...most blisters are osmotic which are below the water line and deeper into the CSM....but there again are not a structural issue and CANNOT lead to further penetration any deeper then the resin starved fiberglass extends.which is almost always limited to the CSM..If your structural lay up is resin starved you have potentially a nightmare on your hands and a peal job with new layup of epoxy resin glass is the best recourse.

I have personally inspected quite a few peal jobs now...and they are effective in removing the problem CSM from the rest of the hull....what I don't like about the procedure is that in doing so ther is no way not to damage individual fibers on the surface of that structural mat...effectively turning the layer into CSM...Saturating every fiber once again with epoxy is critical to making sure your now new surface dosent become the next front of osmotic attack.

This is why I said I would love it if all the CSM would just all fall off my boat...as I have no plan to peal it and dammage its surface to lay another one up on a perfectly sound structural layer.

If its just in the CSM as is 99% of the issues if seen..leave them or repair them to suit your fancy...they CAN NOT sink you...they are the equivalent to a pimple on your skin....unsightly and annoying but your guts cant fall out of your body due to them.

[JiffyLube]

Thank you the advice guys.

[RichH]

Hull Blisters on Boats and Yachts - by David Pascoe, Marine Surveyor