A Bazillion Blisters - Will They Get Worse?

[captsam54]

I had a 65' Hatteras motor yacht peeled last Jan for $4500.00 Then came the hard work.... Everyone suggested we grind em, fill em, paint them and go on.... But no.. I had to do it right.. Ended up costing 12+ grand... But have a new bottom now...

[bailsout]

I never worked so hard on my last haul out on the same number and size of blisters on my 1966 columbia 29. The boat had been "flxed" of blisters maybe 20 years prior. 30 days of belt sanding with 50-60 grit. Hot warm climate and didn't have the time to let it dry for 2-3 months or more which is usually recommended. 5 coats of 2000e barrier coat. 2 coats of high copper bottom paint. Final haul out expenses, my labor, under 2k. we'll see in two years how well it took. I never spent that much time on my mahogany planked Kingscruiser. Less maintenance issues on a glass boat is a myth especially with a boat cover to protect the varnish.

[Matt Johnson]

Just watched a 32' get peeled for $2,000 next to me. The total cost is estimated at $6500.00, but based on the extra work I've seen, its going to be a bit higher. Seems cost varies with location a lot.

Matt

[cabo_sailor]

I had an old Morgan with same problem. Had the hull sand blasted and refaired. Five coats of barrier coat followed by 3 coats of bottom paint. Later sold the boat to a friend whose now had it for 17 years with no new blisters.

Rich

[stevebein]

I had another French boat, a Jeanneau with hundreds or thousands of very small gel coat blisters. When stripped, there were almost no fiberglass blisters. So the thing to verify is are they gel coat or deeper. Good luck.

[carlylelk]

Originally Posted by ScottMeilicke

The surveyor thought it was not structural, and considering the builder and thickness of the hull, probably not a big issue at this time. I think I need to circle back with him.

Let's assume I get it fixed with a full peel and barrier coat. What kind of time am I looking at? I'm not excited about the stories of drying out a hull for months. Can these be washed with IPA or similar to speed up the water removal?

Thanks for the replies all.

Scott: How long will you keep the boat? If you're in the five year range, consider a peel just prior to selling it...not now. For now fix the big blisters and let the small ones go. Boats don't sink because of blisters.

[barnakiel]

If the seller is willing to adjust the price to the fact, I would stick with the boat and fix her up. If you find another you may still face the same job some way down the road. Plastics...

It will be materials, manpower, extended dry storage. Best done in a nice dry and windy place like Canary Islands. ;-)

Think about a project that may take months (not so much work but waiting for her to dry out). Then again you may end up with a hull better than new.

Lovely boat. Good choice. Fair winds.

b.

[a64pilot]

Originally Posted by carlylelk

Scott: How long will you keep the boat? If you're in the five year range, consider a peel just prior to selling it...not now. For now fix the big blisters and let the small ones go. Boats don't sink because of blisters.

I've got groups of them, not thousands, but dozens seemingly in groups. I heavily suspect they came from the bottom job before I bought the boat. From the paperwork it seems hull was sanded down, epoxy applied, painted and splashed. I suspect they essentially sealed in moisture is what happened.
A year later when I pulled the boat to get a bottom job, seemingly there were a whole lot less of them? I wanted them at least blasted and epoxy filled, but the two or so people I asked told me it was a waste of money. Seemed the consensus was it took 27 yrs to get a few .25" blisters, at that growth rate, boat will be over 50 by the time they have grown to the point of needing to get them fixed.
I'm watching them, if they start to grow or multiply, then I will get them fixed.

[monroe0]

The boat is not going to sink because of osmotic blisters. You could sail her for this season, put her back on the hard, grind and let her dry out over winter, then fill, fare, paint, and splash for next year. That's what we did with our Catalina 27. But certainly do take a heavy discount for the problem.

[Defeverboat]

I have a defever 43 has this problem. The cost to take care of it 20k. In stead of peeling you could blast it with nitrogen . Then wash two times a day for three months. This removes the salt sence water goes to salt. There will always be water in the wood.

[Defeverboat]

You can rent a nitrogen machine here. You are freezing the paint off in stead grinding it off. Plus your staying cool.

[ScottMeilicke]

Originally Posted by a64pilot

I suspect they essentially sealed in moisture is what happened.

From what I read in the article I posted earlier, if you don't get rid of the glycol (hydroscopic), you will still have water, which will then continue to suck water through your hull via osmosis, causing more blisters. Since glycol is molecularly much larger than water, it has a much harder time migrating out through the plastic. Therefore you have to cut/grind it out, and washing with warm water helps. Perhaps in your case the epoxy has slowed the osmosis, but it will come back at some point, perhaps through the inside!

[a64pilot]

Mine are in the gelcoat, not the glass. I'm postulating that Gelcoat by itself isn't waterproof and of course will absorb water. If you barrier coat Gelcoat without allowing it to dry out, you may be sealing in the moisture and can get small blisters in the Gelcoat that way.
Now I freely admit I am in no way any kind of composites expert, and would welcome any ideas on my theory from one. My theory may well be silly, but well, who knows?
I've been led to believe by a few that small blisters just in the Gelcoat, are of no great concern, and this from some that would profit from me having them fix them


Sent from my iPad using Cruisers Sailing Forum

[Steadman Uhlich]

The previously linked article was a very interesting read. Lots of information and well illustrated too.

Here are a few excerpts I found interesting and thought might spur some comments here in this thread:

SOURCE: http://www.passionforpaint.co.uk/pdf/osmosis3.pdf

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EXCERPTS:

PAGE 6

"Ironically, the most widely accepted answer to this problem is to ‘dry’ the hull with infra red heaters and dehumidifiers, after which the hull is quickly painted with an epoxy coating scheme ‘before the water gets back in again!'

Unfortunately, this rather simplistic approach to correcting high moisture meter readings usually causes more problems than it solves; for whilst a correctly applied epoxy may slow down the rate of moisture ingress, its densely cross-linked polymers will also prevent the escape of hygroscopic solutes - which means that blistering is even more likely to occur than if the gelcoat was left unprotected!

So: whilst ‘drying’ will undoubtedly help to reduce moisture meter readings, it will do nothing to remove the solutes which are the real cause of our problems, and will not provide a permanent cure. Osmotic breakdown is not a reversible process, so simply removing moisture will never cure it!

I am not suggesting that abnormally high moisture readings should be ignored; but there is usually no need for alarm.

In practice, many yachts are sailed for with ‘high’ moisture readings for ten years or more without their owners being aware of any problems; so the perhaps best advice at this stage would be to leave well alone, whilst keeping an eye on the problem, and delaying any further damage by wintering ashore if at all possible.
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Blistering:
Osmotic blistering is usually a comparatively superficial problem, which only affects the protective gelcoat layer on the outside of the hull. The gelcoat itself is rather like a thick coat of paint, typically about 500 μm (1⁄2 mm) or 20 thou thick; although there can be significant variations in thickness from one part of a hull to another, and between different hulls.
Crucially though, the gelcoat layer itself has very little mechanical strength, and is used only to provide a glossy, hardwearing exterior finish and to help protect the structural laminate beneath it from the effects of water ingress and ultraviolet degradation. Polyester gelcoats are also notoriously brittle, and will readily crack or shatter if stressed, resulting in the characteristic ‘spiders web’ effect.

De-Lamination:
Osmosis does not cause De-lamination, but if the laminate is poorly invested with resin, the internal hydraulic pressure generated by the osmotic process may separate (or de-laminate) any poorly adherent layers (or plies) from one another, severely weakening the hull.

This effect will usually be identified by visible undulation or large ‘swellings’ in the hull surface, although classic ‘Osmotic’ blisters need not be present in the gelcoat.

The hull may also appear slightly ‘soft’ if pressed firmly with a thumb nail or a tool, and may sound ‘dead’ or ‘dull’ if tapped gently with a plastic faced hammer.
In this context, the shape and size of any blister formations will often provide a useful indication of the laminate condition beneath:
• Small, or well formed blisters usually indicate that the gelcoat is adhering well to the laminate, and that the laminate itself has good interlaminar adhesion.
• Shallow and irregularly shaped blisters are usually formed where adhesion between the gelcoat and structural laminate is poor. In some instances, two or more blisters will merge together to form larger blisters, again indicating poor adhesion between the gelcoat and laminate.
• Very large and shallow blisters, or unevenness (lumpiness) in the hull surface usually indicates some form of de-lamination. 
Whilst most yachts can be sailed perfectly safely with their gelcoats in a blistered condition, symptoms of de-lamination must be investigated by a Surveyor as a priority. "

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END OF CLIP

[neilpride]

One thing is for sure, is a fantastic boat, and worth the osmosis job.... get a discount in my opinión,