Osmosis repair....would you...wouldn't you!!

[gary111160]

I'm nearing the final stages of restoring a 1977 princess 25 and I decided to look into Osmosis repair.

When I purchased a year ago the survey showed osmosis blisters in just two localized areas about 1 or 2 sq meters on the starboard side only one near the transom the other near the bow. As the boat has a low value I wasn't going to spend £5/6k on full repair. Intending to repair just the infected areas and treat any new blisters that appear at lay up time.

However, I came across www.advancedosmosis.co.uk and after a long telephone conversation with Adrian Baker, an incredibly helpful and knowledgeable chap, I'm in two minds what to do.

He basically is suggesting a semi DIY solution. First of all he says if the boat has blisters in only a couple of areas it is pointless to just do them and not the whole hull as it will be everywhere, just not showing yet.

His approach is that he would attend the boat and peel the gelcoat to just above the waterline. (£700.00). Then its left to me 'dry' the hull using steam (he provides instructions to self build a steam cleaning kit. (cost around £220 materials) and power washing. Once the moisture readings are where he wants them I would apply the various coats of epoxy, primers and fillers etc all under his guidance. ( cost of materials around £600.00) so to have the entire hull peeled and re-epoxied for around £1700.

I can tackle most jobs but the thought of doing this myself seems daunting.

Has anyone undertaken the job or had any dealings with this company? Any thoughts greatly welcomed.

Gary

 

[Third mate]

i would do a bit more research before spending large amounts of cash as the myths surrounding osmosis are many and varied. Mainly driven by 'Osmosis repair companies'.

Osmosis is a COSMETIC problem. A boat with osmosis will not sink, nor does osmosis make it structurally unsound. The problem is that it looks unsightly, it will only get worse and it's pretty expensive to put right (unless you do it yourself). A boat with osmosis will be hard to sell because of the above, but it's not unseaworthy and it won't sink.

No doubt you will receive good advice from other members of this forum.

 

[dragoon]

I have the same thing, and it was the same with our previous boat (sail). I don't think you'll ever get your money back, and there's no guarantee it won't come back - all GRP boats will get it at some point in their life.

Your boat won't sink, and it won't stop you enjoying it. The only point it's of any relevance is if you sell it. At that point, you might be looking at getting slightly less than if it was clean. Of course, some people will say they would only buy a boat without osmosis, but we're talking a 1977 boat here, so I think they'll be hard pushed to find one that's 100% clear (this varies manufacturer to manufacturer, and also is dependent on the water that the boat's been kept in).

All IMHO of course, but life's too short.

Cheers,
Paul

 

[DAKA]

pretty much agree with dragoon, having bought, used and sold a boat with osmosis several years ago.

even if you have it repaired professionally some will not touch with a barge pole.

I would however self treat the two small areas, dig out each blister, pressure wash, detergent, pressure wash , ambient dry a month and epoxy coat, fill and antifoul, not a long job.
dry berth for at least 6 weeks a year.

many have done this and problems have not been found in later surveys.

 

[Elessar]

I'm nearing the final stages of restoring a 1977 princess 25 and I decided to look into Osmosis repair.

When I purchased a year ago the survey showed osmosis blisters in just two localized areas about 1 or 2 sq meters on the starboard side only one near the transom the other near the bow. As the boat has a low value I wasn't going to spend £5/6k on full repair. Intending to repair just the infected areas and treat any new blisters that appear at lay up time.

However, I came across www.advancedosmosis.co.uk and after a long telephone conversation with Adrian Baker, an incredibly helpful and knowledgeable chap, I'm in two minds what to do.

He basically is suggesting a semi DIY solution. First of all he says if the boat has blisters in only a couple of areas it is pointless to just do them and not the whole hull as it will be everywhere, just not showing yet.

His approach is that he would attend the boat and peel the gelcoat to just above the waterline. (£700.00). Then its left to me 'dry' the hull using steam (he provides instructions to self build a steam cleaning kit. (cost around £220 materials) and power washing. Once the moisture readings are where he wants them I would apply the various coats of epoxy, primers and fillers etc all under his guidance. ( cost of materials around £600.00) so to have the entire hull peeled and re-epoxied for around £1700.

I can tackle most jobs but the thought of doing this myself seems daunting.

Has anyone undertaken the job or had any dealings with this company? Any thoughts greatly welcomed.

Gary

Sounds like he has offered good advice and a fair price to me. If you can use a roller and a sander, and can follow instructions re mixing and overcoating times, you can do this yourself no problem.

 

[Elessar]

pretty much agree with dragoon, having bought, used and sold a boat with osmosis several years ago.

even if you have it repaired professionally some will not touch with a barge pole.

I would however self treat the two small areas, dig out each blister, pressure wash, detergent, pressure wash , ambient dry a month and epoxy coat, fill and antifoul, not a long job.
dry berth for at least 6 weeks a year.

many have done this and problems have not been found in later surveys.

tell me what the 6 weeks a year acheives then please

 

[DAKA]

If bilges are empted, hatches left open then 6 weeks allows drying time and delays the onset/rate of ?wikking? leading to blistering.

imho

 

[SailingEcosse]

I'm nearing the end (hopefully) of the same process, and also spoke to Adrian several times and at length, definitely a top guy and knows his stuff.
One word of warning before going down this route though, the steam cleaning process didn't work for me (the extra peeling required that would have allowed it to work would have left very little laminate ) and I had to go down the hotvac route (search for osmosis and blowtorch ) in order to get the hull to dry enough for epoxy (1980 colvic) all of which has soaked up a lot of my time, although certainly saved a lot of hard cash in the process.

But it is a lot of work no matter what method it needs, so make sure you understand just how much before starting down this route.

I would also agree with what others have said, in that it rarely appears to cure the problem, but if done properly will certainly put it back for a number of years (how long seems to depend on a lot of different factors)

All the best with it though

 

[Elessar]

If bilges are empted, hatches left open then 6 weeks allows drying time and delays the onset/rate of ?wikking? leading to blistering.

imho

it certainly is often believed that the boat will dry a little if left out.

It won't dry - the water when it passes through the porous gelcoat, which it does from the day the boat is launched, desolves part of the resin and becomes heavier. Just like salt water is heavier than fresh. So it can't come out again without peeling, the gelcoat is a 1 way valve.

However you are out of the water for 10% of the time so will have 10% less water absorbed, so there is a benefit, just not as much as is the folklore suggests.

and thats imho.....

 

[DAKA]

it certainly is often believed that the boat will dry a little if left out.

It won't dry - the water when it passes through the porous gelcoat, which it does from the day the boat is launched, desolves part of the resin and becomes heavier. Just like salt water is heavier than fresh. So it can't come out again without peeling, the gelcoat is a 1 way valve.

However you are out of the water for 10% of the time so will have 10% less water absorbed, so there is a benefit, just not as much as is the folklore suggests.

and thats imho.....

very interesting and I am not up to date on the subject to argue, now just thinking out loud.............

If the boat is removed from the water, bilges emptied/drained and hatches opened, accepting your theory then there is still a very good opportunity to dry from the inside through wikking .
Once out the water the hull would normally increase in temperature during the day to help evaporation .

Otherwise I am at a loss as to explain why so many old boats that lift out for the winter dry out so well including blisters shrinking in size(depth not circumference).

Just a thought, not even an opinion never mind an argument !

 

[Elessar]

very interesting and I am not up to date on the subject to argue, now just thinking out loud.............

If the boat is removed from the water, bilges emptied/drained and hatches opened, accepting your theory then there is still a very good opportunity to dry from the inside through wikking .
Once out the water the hull would normally increase in temperature during the day to help evaporation .

Otherwise I am at a loss as to explain why so many old boats that lift out for the winter dry out so well including blisters shrinking in size(depth not circumference).

Just a thought, not even an opinion never mind an argument !

not taken as an argument!!

afaik, once you get to stage 3 osmosis (ie visible bubbles) the gelcoat is damaged enought to be permeable. So bubbles will dry out and shrink.

in its normal state, gelcoat is semi permeable, so the water won't dry out of the "good" bits of boat, where the 1 way valve theory applies.

the most amazing effect thoough is a stage 3 osmotic boat that is blasted using our hot water system. The water in the bubbles gets warm and you watch them grow significantly over the hour after the blast has finished. Osmosis before your very eyes. They shrink again of course and the boat overdue for attention by then.

 

[gary111160]

Thanks for input. Think I'll stick with localized repairs rather than full osmosis treatment.

However on a boat of greater value I do think this option at the price is really viable.

The research I've done certainley demonstrates that repairing a boat with osmosis does not have to cost a fortune.

Thanks again for all your comments

Gary

 

[[27631]]

.........peeling gelcoat..

Hi... 2 years ago I got Paul at Symblast..[Simblast]??? from Poole to peel a 38 ft Finnsailer for me ...about £700.
I then spent 2-3 hours/day with a h/duty steam cleaner...used at point blank range..at 140 deg C and about 100 bar [1400 psi] going over the bottom really slowly and intensely for 21 days.
Then left it for May,June,July,,....Then repeated the above steam treatment for about 7 days...left it for about 3 weeks.
It was amazing at the quantity of milky looking acids etc that came out!!
Then laid it up with Blakes epoxy filler and finish....cost £1000 materials.
JWS ..Southsea Marina loaned their cleaner..about £ 140
Achieved a cheap superb finish for a job quoted at £8-9000.....
BUT....it was seriously hot hard work.
Got an independent party to take and record moisture readings on completion..

 

[PCUK]

tell me what the 6 weeks a year acheives then please

It allows the hull to dry and therefore greatly reduces the chances of Osmosis occurring in the first place - A very well known and proven method of Osmosis prevention.

 

[sarabande]

First of all he says if the boat has blisters in only a couple of areas it is pointless to just do them and not the whole hull as it will be everywhere, just not showing yet.

Gary

That is not true (for any given value of true ) There may be parts of the hull where the layup and gel coat is such that no osmosis will occur. It may be true, but it looks as if a partial treatment may be the cheapest option. Whether that is the best long-term solution for when you sell.....

I must add that the website seems to show he has a healthily open approach to and sound knowledge of osmosis,

 

[DAKA]

but it looks as if a partial treatment may be the cheapest option. Whether that is the best long-term solution for when you sell.....

I think so yes.

Many will not buy a boat that has had osmosis.
Fully professionally treated means its had a serious problem.

a 25 year old boat that had a patch treated 3-4 years ago which hasnt re occurred is acceptable to many.

There are wet patches in a boat.

aft which is often wet in the bilges and had wood strengtheners to soak up water .

for what ever reason the bow section, perhaps the sharpness makes it awkward to layup or perhaps the mould is cooler in the bow section as air circulates more freely outside the mould.

I know of many boats (20-40 years old) that have been owner treated in these areas , then left to dry part of each winter and osmosis has not been found by a surveyor several years later.


PCUK

I think he wants us all to get it so he can grit blast our gel off

 

[gary111160]

That is not true (for any given value of true ) There may be parts of the hull where the layup and gel coat is such that no osmosis will occur. It may be true, but it looks as if a partial treatment may be the cheapest option. Whether that is the best long-term solution for when you sell.....

I must add that the website seems to show he has a healthily open approach to and sound knowledge of osmosis,

Thats what I thought. Surveyor did seem to think it was likely that as the port side is fine that it may have been exasperated due to a difference in build layup at the time.

Also as the boat was open to the elements( broken window) the bilges had been under 6 inches of fresh water for the 6 years prior to me buying her so that wouldn't help and she has spent most, if not all, her life in fresh water as far as I can deduct from dozens of license stickers plastered all over the place!!

I'm going to invest in a moisture meter and monitor readings over the next year and just repair the sections currently blistered.

 

[gary111160]

Hi... 2 years ago I got Paul at Symblast..[Simblast]??? from Poole to peel a 38 ft Finnsailer for me ...about £700.
I then spent 2-3 hours/day with a h/duty steam cleaner...used at point blank range..at 140 deg C and about 100 bar [1400 psi] going over the bottom really slowly and intensely for 21 days.
Then left it for May,June,July,,....Then repeated the above steam treatment for about 7 days...left it for about 3 weeks.
It was amazing at the quantity of milky looking acids etc that came out!!
Then laid it up with Blakes epoxy filler and finish....cost £1000 materials.
JWS ..Southsea Marina loaned their cleaner..about £ 140
Achieved a cheap superb finish for a job quoted at £8-9000.....
BUT....it was seriously hot hard work.
Got an independent party to take and record moisture readings on completion..

Good to get feedback from someone that has actually done it! The savings for hard work are clear. However as the boat is an hour and a half away from me spending all that time just wouldn't be possible. I guess its the man hours that makes professional quotes so expensive.

Did you have any problems with applying the epoxy and or fillers to get a smooth finish?

 

[[27631]]

.man hours

ummmmm.....yes..mmm..about 150...man hours that is...saved say £6000...good pay per hour..but...hard work..and..you gotta get it right.....£40 / hour on a job like that may well be the labour content of the job by a company...2/3 of their cost is labour on an osmosis job..
hope that gives you a better view of costing......

 

[penfold]

Thats what I thought. Surveyor did seem to think it was likely that as the port side is fine that it may have been exasperated due to a difference in build layup at the time.

That's it in a nutshell; one side is fine and the other not, perhaps because one was moulded on a damp cold day with the shed door open, or laminated by the YTS kid who shouldn't have been promoted from floorsweeping, or the pot was mixed badly or from stale resin, or the laminator went for lunch halfway through the layup. There are myriad potential reasons one part of the hull remains sound while another goes bad.