Osmosis treatment; surveyor supervision or not?

[Charlie Boy]

40 year old boat, antifoul blasted off, hull sanded back to reveal blisters.
So the yard manager, who is extremely experienced, feels that the boat needs a ‘peel’ followed by lengthy washing, drying, filling, epoxying etc etc. I trust his judgement and for all of this I will engage appropriate people, or the yard manager will do, or I will do.

There was a discussion on the merits or otherwise of engaging a surveyor to give oversight and to sign the job off.
Is this worth it? What’s the panel’s view?

 

[RunAgroundHard]

I would be wanting an independent surveyor to justify the yard managers "feel" before committing to such an extreme process. On occasion there have been claims made on this forum where osmosis treatments not been done properly. I would want to make sure that any process used is technically established to deliver the correct results, and applied correctly. Employing a surveyor, to look after your interests, should the work be required, would be good idea. Make sure that there are clear and agreed hold points in the plan for the surveyor to check critical facts.

First of all I would be wanting to understand why, pricking the blisters, grinding back, drying off and filling, was not a suitable repair method, compared to a full hull peel. Could a hot vac process not be used or is the damage all over the hull? Lots of questions that need to be addressed to justify the "feel".

Personally, as a +40 year old GRP boat owner, I would not consider a peel at this age of boat but would want to treat each blister individually (if realistic).

Good luck with your decisions.

 

[geem]

Does it really need doing? How many blisters? What size?. You can often leave blisters for years and they get no worse. Maybe better to wait until you are selling to either sell with osmosis or repair and sell it with an osmosis 5 year warranty.

 

[Concerto]

CharlieBoy, I would read this recent thread.
Small osmosis blisters in a 50 y.o. yacht - so what or dangerous?

Personally I would only grind and fill the affected blistered areas and go sailing. Repeat this every time you see blisteres. This will cost little to do and when you do come to sell in the future, it will appear virtually osmosis free.

 

[billskip]

I would say, don't peel it...I was foolish enough to listen and forked out a lot of beer tokens and had my boat done only to find under the surface there was no problem at all.
..they made a really bad job of re coating it and you could always see slight irregularities in the shape.
As said by others dig out and repair.

 

[Chiara’s slave]

I though peeling your gel coat went out at the turn of the century. No boat has ever sunk from blisters.

 

[Charlie Boy]

Perhaps I should have mentioned that the blisters are ‘weeping’ through the gelcoat after just the sanding process

 

[Chiara’s slave]

Perhaps I should have mentioned that the blisters are ‘weeping’ through the gelcoat after just the sanding process

I have a friend that had his osmosis ‘cured’ like this, years ago. It cost a small fortune. As I understand it, the blisters are only there because they contain liquid, the weeping is unsurprising. What is now generally accepted is that other consequences are quite limited, and that spot treatment is quicker, easier, much less expensive and just as effective. If I’ve got that wrong, I’m sure we’ll be told so very shortly.

 

[neilf39]

Blisters need to be popped and ground back and flushed with fresh water several times. How many and how big. If they are wet and you want to do it properly you will need to let the hull dry out. This can be done 'quickly' by using heated vacuum plates as per Hayling Yacht Co or leaving ashore for many months. Those of us who want to go sailing just treat each as it arises. Come out over winter, pop grind and flush any blisters. Epoxy fill in spring, antifoul and go.

 

[Momac]

The surveyor can only comment of what he sees which would have little value. How often do you expect the surveyor to visit / how many visits and what do you expect to get out of it?

Really the responsibility for the work has to rest with the people doing the work. So if you want a warranty that would best come from the people do the work....... but good luck with that . All they ca say is they have done the work in accordance with a specification. Do you have a written specification for materials methods finishes and standards? If not that would be a good start .

 

[RunAgroundHard]

The surveyor can only comment of what he sees which would have little value. How often do you expect the surveyor to visit / how many visits and what do you expect to get out of it?

Really the responsibility for the work has to rest with the people doing the work. So if you want a warranty that would best come from the people do the work....... but good luck with that . All they ca say is they have done the work in accordance with a specification. Do you have a written specification for materials methods finishes and standards? If not that would be a good start .

The surveyor can review the repair process, endorse the scope of work, the project plan can contain hold points or check points for the surveyor to be present and verify critical items. Surveyors, whether housebuilding, yacht building or significant repairs can be a very worthwhile assurance activity for the bill payer. However, it will raise costs engaging a good surveyor.

 

[Obi]

My yacht had the full strip back, treat, leech, harden, reapply and paint. It was about £30,000 on a 40' in 2006 at Desty's IIRC. There was surveyor oversight, don't regret it for the small additional cost in the light of the over all costs. Future proofed the yacht and after the gel coat and a new pseudo teak deck it looked great. Worth every penny.

However, someone else has a lot to say on the subject and it might be worth a read: Which sailboat?

 

[billskip]

Perhaps I should have mentioned that the blisters are ‘weeping’ through the gelcoat after just the sanding process

This is really down to your peace of mind, and how much you want to spend.
I think an answer to the questions asked above .." how big and how many blisters" would help others trying to give advice.
I can only speak of my experience, which at that time there was no Internet forums to seek opinions.
I would advise (not having seen the problem) "peeling off" to be the last resort .
However it's your peace of mind about your boat that matters most.

 

[Refueler]

Lets look at this in real terms :

First need information >

1. What boat is it ?
2. Is the value of the boat greater than the cost of the treatment suggested by Yard Manager ?
3. How extensive is the blistering ?
4. How large are the blisters ?

A 40yr old boat blasted - then sanded ... blisters weeping ... TBH - that would be expected as the sanding would most likely have nipped the top of the blisters allowing them to weep, as blisters are caused by the pressure of the fluid inside.
40yr old boat with blisters - she's probably had blisters for most of her life and they have just become more visible now - with the blasting etc.

Personally - it would have to be bad before I would pay out on a 40yr old boat for peeling and recoating. The method of Pop - Grind - Wash - Fill - sand - paint is the more reasonable IMHO ....

 

[Dellquay13]

This quote about Osmosis from a very recent Duncan Kent article in YM has probably alarmed a lot of people

‘These can usually be sorted out using relatively non-invasive methods but voids deep inside the composite can cause the hull to delaminate, eventually creating a high risk of the vessel actually sinking.’

Lots of us just sort out the individual blisters as they pop up, but some people will read that and get very worried.

I’m not endorsing that article in any way, just pointing it out to others who might have missed it.

 

[billskip]

, eventually creating a high risk of the vessel actually sinking.’

Can you or anyone quote an actual instance? Do insurance companies consider it high (or any) risk?
I have seen "delamination" exposed hull and yes it looks ugly, however I think extremely rare....there is normally a "history " of specific builders (suggesting caution with their make /model,) so if the make model is known more information could possibly be gained.

 

[Dellquay13]

Can you or anyone quote an actual instance? Do insurance companies consider it high (or any) risk?
I have seen "delamination" exposed hull and yes it looks ugly, however I think extremely rare....there is normally a "history " of specific builders (suggesting caution with their make /model,) so if the make model is known more information could possibly be gained.

You will have to ask Duncan Kent, I only highlighted his recent article for anyone who wants to comment further. I don’t know enough about it to make any statement.
If he chooses to publish his opinion without reference to evidence, then it is his choice

 

[Stemar]

I haven't read the article, but I'd want to know what sort of voids, how big and under what circumstances could they sink a boat. ISTM that a gelcoat peel isn't going to uncover deep voids anyway, unless they're huge - dinner plate sized, not just blisters, but areas of serious delamination, like a couple of big boats (Oysters?) a few years ago. If it hasn't shown up a long time ago on a 40 year old boat, I reckon the chances of such an issue being present is vanishingly small.

Isolated blisters, even a lot of them, aren't something I'd be too concerned about, As others have said, dig'em out, fill 'em in with epoxy and go sailing. Chances are there'll be more next year, so give them the same treatment.

 

[Charlie Boy]

Surveyor on Thursday for the (hopefully) definitive view. Visually there appear to be patches of voids with occasional weepers. The patches are fairly widespread.
We shall see, I’ll report back

 

[Charlie Boy]

So, surveyor yesterday. NOT full blisters; he calls it ‘wicking’. Moisture readings just at the top of amber/low reds. Tap testing produced nothing but solid noises. All good for a 40 year Sadler 32. Problems would be more likely if double hull foam filled.
Conclusion; Fill, fair, Gelshield (or equivalent), go sailing.
All very reassuring and a thoroughly nice bloke.
Joe Kershaw - Yacht and Small Craft Surveyor Suffolk