Cost of osmosis repair

[Sarh Dee]

We have a 33 ft fin keel yacht that needs osmosis treatment. Any ideas on a worst case scenario ball park figure on cost to get sorted . We are hoping to take her to Portishead to get her out of the water so any local recommendations would be appreciated

 

[Topcat47]

My 26'er was done for £3k about ten years ago. Scaling up for vessel size means that it would have cost around £5k for a 33 so I'd be looking about £6-6.5k now.

 

[pcatterall]

The time it will take to dry out can be significant, it can be a long process. There are many ways to speed the process and these can add a lot more to the expense. Once dry the cost of protecting the hull is more straight forward to calculate. You may wish to consider copper coat at the 'protection stage'.
Our own hull dried out 'naturally over an English summer and winter, the hull had been blasted so we epoxied her ourselves which took 2 days and a few hundred pounds using the West 'system'.

 

[macd]

...the hull had been blasted so we epoxied her ourselves which took 2 days and a few hundred pounds using the West 'system'.

I very much hope it went well, but can't think of an epoxy less suited to barrier-coating in UK conditions than West. It's propensity for amine blush in cool, humid conditions is both legendary and a pain in the underwater profile. And it's silly money.

 

[sailaboutvic]

Ok hang on to your horse .
Some months back a guy I know asked a well known guy who does GRP work , copper coating , ossmosis treatment ,in Greece .
He happen to be English , he shown me the email reply , I nearly died 14k . Euros , on a 42 foot boa

 

[pcatterall]

I very much hope it went well, but can't think of an epoxy less suited to barrier-coating in UK conditions than West. It's propensity for amine blush in cool, humid conditions is both legendary and a pain in the underwater profile. And it's silly money.

Yes it went well and is fine 5 years on, we applied wet on 'tacky' and were spared any blushes.

 

[CFarr]

I had my 36' done in 2013/14.
Estimate was £4800, final cost was nearer £8000.
Also took about a year longer than we thought it would.
If I had that time over again I'd just take it sailing.

 

[savageseadog]

It's a very basic job that can be DIY'd, I wouldn't spend major monies having a yard or specialist do it.

 

[Trundlebug]

It's a very basic job that can be DIY'd, I wouldn't spend major monies having a yard or specialist do it.

+1.
And this is the PBO forum after all.

Lift the boat out, clean it off, crawl underneath and pop the blisters.
Rinse them thoroughly with fresh water.
Leave for a month (or several, e.g. over the winter) to dry out.
Buy some epoxy paste / filler stuff (can't remember which stuff it is so do your own research) and return in the spring to fill the blister holes.

Antifoul and go sailing.
Repeat every time you haul out until the blisters stop appearing.

That's what a friend of mine does on his boat. The epoxy isn't cheap IIRC, around £50 a tin, but rather cheaper than the £thousands some are espousing on here.
At the last lift out there were no blisters, so job done. And there's no disruption to his boating.

I'll admit the crawling around underneath the boat in the cold weather to fill the holes isn't the nicest of jobs, but worth it considering the savings.

 

[macd]

Trundlebugs running repair approach has much to commend it, particularly on a boat without high value.

I'd do a little more than pop any blisters, wash, wait and fill, though. Osmosis produces chemicals which are hygroscopic and will attract water for ever. So grinding out all the affected material in any particular blister is a better approach, then repeated high-pressure washing to get rid of the hygroscopic elements. Then dry, then fill.

It's usually the case that the blisters are close to the surface, typically one side or the other of the tissue layer immediately below the gelcoat. That being so, quite aggressive grinding is possible. Blisters are rarely deep or large enough to compromise mechanical strength, but if they are, a more comprehensive approach may be necessary.

 

[MagicalArmchair]

My late father was a shipwright and was scathing about osmosis. How many GRP boats do you know that have actually sunk from it? (queue the many googled responses ) My father gel peeled and treated many boats, he would usually advise the people coming to him asking for the (exceedingly expensive) process to just go sailing and stop worrying about it.

My boat, when I purchased her was nearly bought by someone else. They had a per purchase survey done that claimed she had osmosis leading to the sale falling through (the survey was done without a moisture meter)! My father put his moisture meter on her, she was dry as a bone, and the very few bubbles the surveyor suggested were osmosis we very few and likely from original manufacture. I've had her ten years, no bubbles and no problems...

How bad is your osmosis?

 

[Steve_N]

Trundlebugs running repair approach has much to commend it, particularly on a boat without high value.

I'd do a little more than pop any blisters, wash, wait and fill, though. Osmosis produces chemicals which are hygroscopic and will attract water for ever. So grinding out all the affected material in any particular blister is a better approach, then repeated high-pressure washing to get rid of the hygroscopic elements. Then dry, then fill.

It's usually the case that the blisters are close to the surface, typically one side or the other of the tissue layer immediately below the gelcoat. That being so, quite aggressive grinding is possible. Blisters are rarely deep or large enough to compromise mechanical strength, but if they are, a more comprehensive approach may be necessary.

My approach has been similar i.e. DIY and then running repairs to the blistered 37' boat that I bought 14 years ago.
I ground out the blisters down to clean, dry laminate using either a flap disc in an angle grider or a blunted countersink bit in an electric drill; the latter is less dramatic!
I washed and dried the resulting craters several times but didn't power wash.
Then repaired with West epoxy and small cut circles of laminate where big/deep enough and filled first with epoxy mixed with colloidal silica then epoxy and West lightweight filler for ease of fairing.

I must have done around 500 blisters I would think using less than £125 of supplies.
12 seasons later (admittedly our seasons are quite short and we never winter afloat) running repairs have been limited to the areas underneath the cradle pads with nothing worthy of treatment appearing elsewhere on the hull.

For this particular boat it was definately the correct course of action.

 

[CFarr]

+1.
And this is the PBO forum after all.

Lift the boat out, clean it off, crawl underneath and pop the blisters.
Rinse them thoroughly with fresh water.
Leave for a month (or several, e.g. over the winter) to dry out.
Buy some epoxy paste / filler stuff (can't remember which stuff it is so do your own research) and return in the spring to fill the blister holes.

Antifoul and go sailing.
Repeat every time you haul out until the blisters stop appearing.

That's what a friend of mine does on his boat. The epoxy isn't cheap IIRC, around £50 a tin, but rather cheaper than the £thousands some are espousing on here.
At the last lift out there were no blisters, so job done. And there's no disruption to his boating.

I'll admit the crawling around underneath the boat in the cold weather to fill the holes isn't the nicest of jobs, but worth it considering the savings.

Depends on the level of osmosis I suppose.
My boat had many, many blisters all over the hull so I needed a full gelcoat peel followed nearly a year later by skimming off a layer of laminate as she just wasn't drying.
This then needed a new layer of biaxial cloth and finishing off with epoxy.
A superb job in the end but as I said, if I'd known then what I know now I'd have just gone sailing.

 

[jwilson]

I had my 36' done in 2013/14.
Estimate was £4800, final cost was nearer £8000.
Also took about a year longer than we thought it would.
If I had that time over again I'd just take it sailing.

Yes - this is the problem with getting a yard to do the work: once they have started you have more or less written a blank cheque for any other work found necessary: ie delamination patches, not drying so cut/blast deeper, then relaminate with cloth to restore hull thickness, etc. Also the time taken to dry can vary greatly. I have known of boats out of action 2 years (and clocking up storage bills).

 

[pcatterall]

Prior to the boat I described working on in my previous comment we had an old Colvic Atlanta. There were quite a few blisters and we used the clean out and fill method described by others.
In year one we did about a quarter of the hull, in year 2 we did another quarter and returned to do a few ( but significantly less than in year one) in the year one area,.
We then sold the boat but the method seemed that it would have worked.
Why not just use this DIY method on a good sized area this winter and see how it goes? remembering the good advice that there are no reports of boats sinking due to osmosis.

 

[Bandit]

Does it really need doing?

What kind of value is the boat? Is it worth doing.

if it's high value and you intend selling I would do it.

Years ago I had an in depth conversation with a paint/grp expert consultant his view was don try and do a quick job.

Take it out of the water as early as possible, August or September have all underwater area slurry blasted with a coarse grit to remove gelcoat, pressure wash with a hot water pressure washer or steam cleaner many times, leave it completely bare to dry off over the winter outside in wind and rain. Buy a moisture meter and monitor the moisture level until it comes down to a good level then when it gets warmer May or June then fill and then recoat.

He did not believe in vacuum pads, hot pads or infra red lights as he reckoned all it did was dry the surface and concentrate the solvents deep in the grp to cause problems in the future.

 

[salignac]

A friend has recently been getting quotes regarding Osmosis repair on a 28 footer. Costs run to approx £3,500 to £4,000.

A similar process to Bandit's previous post was suggested without the steam cleaning though.

 

[lapis12]

Thanks friend for sharing this, I was just about to start the process without drying.and it literally takes a lot of time

 

[neilf39]

I had a quote from Hayling Yacht Company for about £6k for a 29 ft boat a while back. About a third the value of the boat. They strip the gel coat and put drying pads on. Needless to say I did not do this. I had the hull soda blasted and then just sanded and filled the blisters (most were small) after letting them dry out for about 3 months before filling. I then gelshielded the hull with 4 coats on the basis that if it did not stay on nothing lost. It has been on for four years now with no issues. Cost under £400 for soda blast and all materials, just took a bit of time.

 

[CAPTAIN FANTASTIC]

This is an old post but the comments and solutions to osmosis are still valid. Boats don't sink due to osmosis. Osmosis is similar to Japanese Knotweed, peope can get hysterical and paranoic about it and can spend huge amount of money. I know that there is the occational case where osmosis has been confused with delamination; delamination is very different to osmosis with the occational structural failure.