how long a life for gelshield

[Little Five]

Bought my boat 2 years ago and in the notes from previous owner it says boat had all antfoul removed and 2 coats of gelshield 200 applied during winter 2006/7 My question is- if I left the boat in the water how long would it be before penetration of the 2 coats took place?

 

[VicS]

Goodness knows.
It should been given a minimum of 5 coats according to International Yachtpaint

 

[alan006]

Whilst I can't give you a precise figure may I make a couple of comments. Firstly epoxy coatings are not 100% waterproof ( I know they are close and much better than polyester but they are not 100%) consequently although they will improve the resistance to moisture ingress it would seem wise to carry on letting the hull dry out at regular intervals.

 

[Little Five]

Whilst I can't give you a precise figure may I make a couple of comments. Firstly epoxy coatings are not 100% waterproof ( I know they are close and much better than polyester but they are not 100%) consequently although they will improve the resistance to moisture ingress it would seem wise to carry on letting the hull dry out at regular intervals.

Ok. Say the gelshield slows down the process of water absorbtion does the reverse apply that the boat would take longer to dry out?

 

[PeterGibbs]

Bought my boat 2 years ago and in the notes from previous owner it says boat had all antfoul removed and 2 coats of gelshield 200 applied during winter 2006/7 My question is- if I left the boat in the water how long would it be before penetration of the 2 coats took place?

2 coats of Gelshield is a minor improvement over naked gell coat and cannot be relied on.
It works by building sufficient microns to be a serious barrier to moisutre - 5 coats are needed.

The UK practice with osmosis, and removing the boat from the water regularly is an oddity, one not followed in most parts of the world. I guess it arose because GRP techniques were pioneeded in this country, and in the early days boats did show osmosis on a number of occasions. There were lurid tales of a "risk you could put your hand through the side of your boat" if struck by it! I kid you not. it was never that much of a structural threat.

Now, laying up techniques are much improved, and the risk is much lower. Even when it occurs it's not the end of the world. But it's true that stripping and washing out / drying / re-gelling is expensive. You cannot say when it might occur - there's no correlation between moisture readings and osmotic bubbling. Many boats over 20 years of age have no symptoms etc.

In many countries from New Zealand to northern Europe, GRP boats are almost never routinely taken out of the water for any length of time - as many do here - "for the winter dryout." So what can we conclude? Hauling for the winter confers no discernable advantage? Proabably.

PWG

 

[Little Five]

2 coats of Gelshield is a minor improvement over naked gell coat and cannot be relied on.
It works by building sufficient microns to be a serious barrier to moisutre - 5 coats are needed.

The UK practice with osmosis, and removing the boat from the water regularly is an oddity, one not followed in most parts of the world. I guess it arose because GRP techniques were pioneeded in this country, and in the early days boats did show osmosis on a number of occasions. There were lurid tales of a "risk you could put your hand through the side of your boat" if struck by it! I kid you not. it was never that much of a structural threat.

Now, laying up techniques are much improved, and the risk is much lower. Even when it occurs it's not the end of the world. But it's true that stripping and washing out / drying / re-gelling is expensive. You cannot say when it might occur - there's no correlation between moisture readings and osmotic bubbling. Many boats over 20 years of age have no symptoms etc.

In many countries from New Zealand to northern Europe, GRP boats are almost never routinely taken out of the water for any length of time - as many do here - "for the winter dryout." So what can we conclude? Hauling for the winter confers no discernable advantage? Proabably.

PWG

Carefully words post PWG. Are you a politician?

 

[Elessar]

Ok. Say the gelshield slows down the process of water absorbtion does the reverse apply that the boat would take longer to dry out?

Epoxy is about 25 times more waterproof than gelcoat. It slows down water ingress to the point where it is insignificant. Who knows whether 2 coats of gelshield will work, but it must be better than no epoxy at all.

It is a myth though that boats dry out over the winter. Boats dry over a couple of days, (or a couple of weeks for older gelcoats) , but the water that's passed through the gelcoat - an inevitable process- does not come back out again I'm afraid.

If you haven't got an epoxy coat you have got the advantage that the boat isn't getting wetter over the winter if you come ashore, but it isn't really getting any drier either.

BTW the solvent free epoxies we use will give you 400 microns or so of protection (enough) in just 2 coats applied by roller and you can actually put it on up to an incredible 1000 microns (1mm) in 1 coat by spray. This isn't possible with solvented epoxies because even if it didn't run you'd get solvent entrapment and it'll bubble. This is why products like gelshield need lots of thin coats. But it doesn't matter how you get the epoxy on the boat or which one you use - once cured it will protect your boat from water ingress.

________________

ARC. Antifoul Removal, Epoxy Coatings, CopperCoat

Noisekiller Marine. Automotive acoustic technology now available for your boat

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[Elessar]

Bought my boat 2 years ago and in the notes from previous owner it says boat had all antfoul removed and 2 coats of gelshield 200 applied during winter 2006/7 My question is- if I left the boat in the water how long would it be before penetration of the 2 coats took place?

Not possible to answer your question - except to say longer than if there were no gelshield.

If it were my boat, I'd lose no sleep over it until I had some time available, then I'd put some extra layers of epoxy on for peace of mind.

________________

ARC. Antifoul Removal, Epoxy Coatings, CopperCoat

Noisekiller Marine. Automotive acoustic technology now available for your boat

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[Little Five]

Not possible to answer your question - except to say longer than if there were no gelshield.

If it were my boat, I'd lose no sleep over it until I had some time available, then I'd put some extra layers of epoxy on for peace of mind.

________________

ARC. Antifoul Removal, Epoxy Coatings, CopperCoat

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Hi Elessar.
Thanks for reply. Another question I am afraid. How best to remove antifoul without affecting gelshield and how to prep gelshield to receive more layers.
Thanks.

 

[Elessar]

Hi Elessar.
Thanks for reply. Another question I am afraid. How best to remove antifoul without affecting gelshield and how to prep gelshield to receive more layers.
Thanks.

If you're lucky you'll only have 1 lot of antifoul over the gelshield and it will come off quite easily. Gelshield does give a naturally matt surface which gives a good key though. Try scraping it and see you might be lucky.
You can use chemical removers, if you do put clingfilm over the wet remover to keep it wet for long enough for it to work, wear protective clothing and whatever you do don't sit on the spoils even with protective gear. Ignore that last bit at your peril.
We and other like us can of course remove it (and leave the gelshiled on) but that will cost you money.....
Once scraped, give it a once over with a sander to remove any imperfections and you can apply more gelshield or other epoxy at will.

________________

ARC. Antifoul Removal, Epoxy Coatings, CopperCoat

Noisekiller Marine. Automotive acoustic technology now available for your boat

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[Boo2]

So what can we conclude? Hauling for the winter confers no discernable advantage?

To reach that conclusion wouldn't we need to know the relative frequency of osmosis in boats from countries where drying out is routine compared with those where it is not ?

Boo2

 

[Deleted member 36384]

.... It is a myth though that boats dry out over the winter. Boats dry over a couple of days, (or a couple of weeks for older gelcoats) , but the water that's passed through the gelcoat - an inevitable process- does not come back out again I'm afraid......

I would like to understand why you think this is the case. You cant have it both ways, drying out and water (or rather its molecules) "not coming back out again. So how does this mass elimination happen when it "does not come back out"?

 

[Seajet]

The whole point of Gelshield is that it's SOLVENT FREE epoxy.

Solvents in normal epoxies have been found to damage gelcoats...

One is supposed to apply 5 coats, it comes in grey & green so that alternating colours may be used, giving a visual clue as to coverage.

 

[Elessar]

The whole point of Gelshield is that it's SOLVENT FREE epoxy.

Solvents in normal epoxies have been found to damage gelcoats...

One is supposed to apply 5 coats, it comes in grey & green so that alternating colours may be used, giving a visual clue as to coverage.

Gelshield plus is solvent free the OP is talking about gelshield 200 which is solvented. Only 45% solids in fact. I don't use it but I very much suspect you're also wrong about it damaging gelcoat as International sell loads of it.

________________

ARC. Antifoul Removal, Epoxy Coatings, CopperCoat

Noisekiller Marine. Automotive acoustic technology now available for your boat

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[Elessar]

I would like to understand why you think this is the case. You cant have it both ways, drying out and water (or rather its molecules) "not coming back out again. So how does this mass elimination happen when it "does not come back out"?

I agree it seems somewhat counter intuitive.

The water passes into the laminate and dissolves hydroscopic elements of the layup - such as propylene glycol. The resultant solute is heavier than water (just as salt water is heavier than fresh) and cannot pass back through the gelcoat.

It the same reason that osmosis happens faster in fresh water, the less dense water can pass through the gelcoat more quickly than salt water.

________________

ARC. Antifoul Removal, Epoxy Coatings, CopperCoat

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[2Tizwoz]

Do fibreglass septic tanks and sewage systems suffer from osmosis?

Are domestic and sectional water tanks similarly susceptible?

They seem to last for decades without problems.

 

[Elessar]

Do fibreglass septic tanks and sewage systems suffer from osmosis?

Are domestic and sectional water tanks similarly susceptible?

They seem to last for decades without problems.

If they are made from GRP with a gelcoat finish then yes. I don't know what they're made of.

Osmosis is “The equalisation of solution strengths by the passage of a solvent (usually water) through a semi permeable membrane”.

Gelcoat is a semi permeable membrane. Thus strictly speaking you get osmosis from day 1 of a new boat - but that's not what people mean by the term osmosis when talking about boats.

Usually they mean stage 3 of the osmotic process when bubbling starts.

But who cares if a tank has a bubble on the inside?

________________

ARC. Antifoul Removal, Epoxy Coatings, CopperCoat

Noisekiller Marine. Automotive acoustic technology now available for your boat

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[doug748]

But who cares if a tank has a bubble on the inside?

-----------

Yes, my water tank has huge bubbles, they may burst someday, I monitor them with interest.

On the topic of Gelshield. I guess mine has been on for 17 years and still seems ok. I have no idea what the condition of the hull was when it went on but I suspect the application was not very well done. Anybody beat 17 years?

 

[Heckler]

But who cares if a tank has a bubble on the inside?

-----------

Yes, my water tank has huge bubbles, they may burst someday, I monitor them with interest.

On the topic of Gelshield. I guess mine has been on for 17 years and still seems ok. I have no idea what the condition of the hull was when it went on but I suspect the application was not very well done. Anybody beat 17 years?

My Bene 351 had them in the water tanks when I bought her, the survey picked them up. they were just little bumps, after 7 years they turned in to larger ones. The survey got me a couple of grand knocked off, the buyers surveyor didnt look for them. My surveyor told me that they would get bigger, they did, that they would make the water taste a bit funny, they did, and that they were not structural and wouldnt let the tanks rupture, they didnt. I suspect all Bnes with integral tanks of that age, 1995, suffer from it!
Stu

 

[Elessar]

My Bene 351 had them in the water tanks when I bought her, the survey picked them up. they were just little bumps, after 7 years they turned in to larger ones. The survey got me a couple of grand knocked off, the buyers surveyor didnt look for them. My surveyor told me that they would get bigger, they did, that they would make the water taste a bit funny, they did, and that they were not structural and wouldnt let the tanks rupture, they didnt. I suspect all Bnes with integral tanks of that age, 1995, suffer from it!
Stu

Bet they do too - fresh water.......

________________

ARC. Antifoul Removal, Epoxy Coatings, CopperCoat

Noisekiller Marine. Automotive acoustic technology now available for your boat

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