smeaks
Well-Known Member
On a hull that has major osmosis blisters will a professional peel and subsequent treatment repair and alleviate the problem or will the osmosis reoccur?
Osmosis treatment effectiveness
- Thread starter smeaks
- Start date
Elessar
Well-Known Member
it will be better than new if done properly.
30boat
N/A
It depends on many factors,mainly how well the treatment was done,which itself depends on how well the hull was cleaned of the contaminants and which barrier coats were applied and how.There's a lot to go wrong.
smeaks
Well-Known Member
This is the proposed method.
Rotory peel the underwater area, repeatedly steam clean to remove the glycol and hygroscopic contaminants.
Dry laminate (natural air and infra red lamps)
Apply one coat of Hempels GelProtect (Solvent free epoxy)
Fil and fair with epoxy fillers
Apply four coats of GelProtect
Apply under water primer
Apply two coats of antifoul
Does it seem correct?
sailorman
Well-Known Member
My previous boat was done as i took her over & that was some 26 yrs ago. She is now being treated again this year.
Products & methods will now be improved on from 26 yrs ago.
You might try the "Hot-Vac" method to speed up drying
Products & methods will now be improved on from 26 yrs ago.
You might try the "Hot-Vac" method to speed up drying
jwilson
Well-Known Member
May re-occur - plenty of boats have now had two "treatments" and some boats have had three. There can be vast differences in quality of work, and equally great differences in the outcome. Just as new boats usually have a warranty that there will be no blisters for 5 years, the "treatments" will usually give a similar blister-free period, though fewer and fewer contractors are now guaranteeing this.
[70521]
Well-Known Member
However, it might be cheaper to buy a new boat.
30boat
N/A
Yes,except over here you won't need the infrared lamps.There's a variety of coatings to choose from.A good solvent free epoxy will work as well as something from an expensive brand.
TimBennet
Well-Known Member
It also depends on what's removed with the rotary peel. If any of the original fibre laminate is removed, then it will need to be replaced and not just 'painted' and filled with epoxy.
You need to have someone knowledgable watch the peeler operator - I've seen some horrible jobs done by cowboy operators
You need to have someone knowledgable watch the peeler operator - I've seen some horrible jobs done by cowboy operators
30boat
N/A
The gelplane is the accepted tool as it's the most efficient and controllable one.It also leaves a good finish for recoating without much fairing.
jwilson
Well-Known Member
Gelplanes tend to leave a bit too smooth a surface for recoating with epoxies: it is regarded as good practice to lightly sandblast after gelplaning to roughen the surface - after all you are taking off a mostly chemically bonded bit of glass/resin to stick something different on top, and a bit of a key is good. The whole job CAN be done with sandblasting, but it is far less controllable than a gelplane - you could sandblast right though the hull.
One snag to starting a "treatment" is that you have then almost handed a blank cheque to the yard -"... we gelplaned off the gelcoat and now we've found some delamination and wicking, we'll have to plane off more and put a new layer of glass over to replace the thickness", etc.
If the boat is a Moody 27 as listed in your profile a full commercial "treatment" is a very expensive exercise in relation to boat value: research your options thoroughly before committing. Read my web page at http://www.yachtsnet.co.uk/osmosis.htm also as much else as you can, including the book "Fibreglass Boats" by Hugo du Plessis.
One snag to starting a "treatment" is that you have then almost handed a blank cheque to the yard -"... we gelplaned off the gelcoat and now we've found some delamination and wicking, we'll have to plane off more and put a new layer of glass over to replace the thickness", etc.
If the boat is a Moody 27 as listed in your profile a full commercial "treatment" is a very expensive exercise in relation to boat value: research your options thoroughly before committing. Read my web page at http://www.yachtsnet.co.uk/osmosis.htm also as much else as you can, including the book "Fibreglass Boats" by Hugo du Plessis.
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Bosun Higgs
N/A
Epoxy like all other coatings is not completely waterproof. Indeed its less waterproof, thickness for thickness, than two pack polyester paint. And any economically viable commercial treatment is likely to leave a bit of the nasties inside the laminate becaue of time and cost constraints so the answer to your question is yes - it may come back. The quality of the work and the thickness of the epoxy coat will determine how long the treatment lasts. But then the average ownership time for a yacht is about 7 years I believe so there's an excellent cchance that the problem will not return in your ownership. And thats why most of the guarantees given were about 5 years or so.
smeaks
Well-Known Member
Not my boat but a potential purchase.......
rogerball0
N/A
Read Hugo de plessis' book and then dont bother doing anything, i have spent the last couple of years undertaking this work on my Centaur and wished i could reverse time to leave the gelcoat on and just have ground back the blisters, i budgetted £2000 to do mine as the labour was free but ended up spending nearly double that, i think the blank cheque comment is apt as once you boats peeled what are you gonna do apart from whatever the boatyard says? For what its worth i left mine for a year to air once the gelcoat was peeled then steam washed daily for three months and still only got it to about 50% dry.
Seriously dont bother, go find a boat that doesn't have the pox.
roger
www.agentlemansyacht.com
Elessar
Well-Known Member
Not quite. You need an abrasive blast after the peel. This takes the shine off that the blades leave and increases surface area, as well as blasting out any soggy mat. Most peelers will quote for a peel and blast as standard.
And you'd be bonkers after all that effort not to put coppercoat on instead of anti foul. They sell solvent free epoxy too BTW.
Elessar
Well-Known Member
It's 25 times more waterproof than gel coat. And 100s of times thicker than the paint you quote. It is waterproof enough.
It will fail if it wasn't dried properly. Get it surveyed before epoxy is applied for peace of mind.
geem
Well-Known Member
We had our catamaran peeled by Adrian Baker. The hull was then sand blasted to find any weak spots in the laminate and provide a key for the epoxy. The hull was left outside for 6months and periodically pressure washed. The hull was checked for moisture content until it was found to be dry. Adrian was the brains and the wife and I the braun. Epoxy primer was painted on, then epoxy filler. We filled and faired that hull until it was better than original. Adrian suggested that the quality of the work done was far better than any yard. We did work very hard but the total cost without our time was £3k for a 37 ft cat. We then coppercoated the hull as well. Five years later the hull is perfect and very smooth. We sold the boat at the end of last year and the surveyor found no issues with the hull or anything actually.
oldsaltoz
Well-Known Member
Older boats were over glassed with very thick and heavy hulls, for this reason it's a good idea to take a little more than the gelcoat off, this will ensure any contaminated areas will easy to spot.
Something to keep in mind if is an older boat.
The cheapest way is to have the hull stripped, then carry out any repairs yourself, with Supervision to start with if you have limited knowledge.
MOST important, ensure the moisture levels are within tolerance BEFORE anything is added to the hull, including any repairs.
Good luck and fair winds.
Something to keep in mind if is an older boat.
The cheapest way is to have the hull stripped, then carry out any repairs yourself, with Supervision to start with if you have limited knowledge.
MOST important, ensure the moisture levels are within tolerance BEFORE anything is added to the hull, including any repairs.
Good luck and fair winds.
JumbleDuck
Well-Known Member
Osmosis treatment is extremely effective for those who carry it out, many of whom are able to buy expensive cars, boats and holidays as a result.
