Blistering under epoxy coat

[bonzo]

I have a 4 year old survey on a boat that reports: "..widespread blistering between the epoxy and the gel coat, no penetration found into gel coat or laminate some of the blisters are fluid filled. Thought to have been caused failure of epoxy coat. With no blistering within the gel coat or laminate it is not considered of structural concern". Is it worth continuing to look at the boat and get my own survey done or better to walk away? Thanks for any help.

 

[jonjo]

It is a point for financial negotiation, say £3k.

Depending in how eager you are to go sailing, get the hull slurry or pumice blasted to strip off the failing paint layer. Leave the hull to stand for 4 warm summer months, then DIY reapply a couple of epoxy paint layers and finish off with Coppercoat.

 

[Bilgediver]

It is a point for financial negotiation, say £3k.

Depending in how eager you are to go sailing, get the hull slurry or pumice blasted to strip off the failing paint layer. Leave the hull to stand for 4 warm summer months, then DIY reapply a couple of epoxy paint layers and finish off with Coppercoat.

Don t forget the hot water washing of the hull while it is "drying" out. Most important for a good job.

 

[Elessar]

I have a 4 year old survey on a boat that reports: "..widespread blistering between the epoxy and the gel coat, no penetration found into gel coat or laminate some of the blisters are fluid filled. Thought to have been caused failure of epoxy coat. With no blistering within the gel coat or laminate it is not considered of structural concern". Is it worth continuing to look at the boat and get my own survey done or better to walk away? Thanks for any help.

Hmmm....

Difficult to blast off epoxy. It will need a lot of sanding afterwards.

How old is the boat? How big is it and what's it worth?

Hot water washing only relevant if the hull is peeled, not if the gelcoat remains.

 

[bonzo]

Blister under epoxy

Hello Elessar,

It's around 35/40 years with an asking price of 9000. If treatment is required it probably isn't worth doing - it would be such a significant percentage of the asking price. It's a heavily laid up hull (not uncommon for boats from the 60s/70s) so I doubt there will be any structural difficulties. I guess it's more a question of resale value.

 

[dombuckley]

Sounds like the epoxy has suffered from "amine sweating", due to incorrect mixing / temperature - this will only affect the epoxy, and will not spread to the underlying polyester gelcoat.

The key statement in the report is that no blistering was found in the gelcoat or laminate (4 years ago), and she was structurally sound. So, if she ticks all the other boxes, I wouldn't walk away from her just because of the failed epoxy.

If you go ahead, definitely get a survey done, to ensure the situation hasn't worsened. If possible be there when its done: a good surveyor will have a lot of practical advice.

 

[Bosun Higgs]

I had this problem when a boat I bought was epoxied with West. The job wasnt done properly and West is prone to amine blush, so it developed blisters that looked for all the world like osmosis. But the fluid in the blisters was alkaline which was the giveaway.

The yard who had cocked up re-pealed the boat and epoxied properly the second time. It didnt need this in all areas since the blush was patchy - its usually caused by cold and damp ( an open shed doorway in my case) between coats.

Personally I would avoid the boat, not for structural reasons but because its all aggro.

 

[robmcg]

Have also owned a boat with this issue and I agree, the boat looks like it has osmosis, with fluid filled blisters etc. I agree with Elessar, the epoxy, although failing will be very hard to remove from the original gel coat. In my case, the easiest and most cost effective solution was to peel the hull as per an osmosis treatment and have her re-epoxied properly. When she was peeled and washed, the surveyor turned up the next day to take moisture readings and declared the hull was dry enough for the work to begin - indicating that the moisture had not penetrated further into the laminate. If you can live with it, no problem but it will have an effect on resale value if you do not correct the problem and it is a fair bit of hassle getting it sorted. I would want a chunk of money taken off to reflect this.

 

[onenyala]

How does the fluid from alkaline filled blisters smell ?
I have the same scenario with my 1972 boat. In 1991 it was peeled down to the glass fibre and dried with over a winter with help from heaters in a boat shed. In the spring of 1992 it was epoxied.
About 5-6 years later there was blistering of the epoxy. The smell of the fluid from the blisters was vinegery. I assume this was due to osmosis possibly as a result of the hull not being washed during drying.
Periodically I have popped the larger blisters and epoxied them. After the initial blistering there does not seem to be an increasing rate of blistering.
The glass fibre which I exposed beneath the blisters seems a sound and hard as a bell.

 

[jonjo]

the epoxy, although failing will be very hard to remove from the original gel coat. In my case, the easiest and most cost effective solution was to peel the hull as per an osmosis treatment and have her re-epoxied properly.

That sounds a bit extreme, did you not investigate other more exotic forms of blast stripping, Co2, Soda, pumice, slurry?