Epoxy treatment

[david_e]

Appreciate why people might treat a new boat (although mfctrers today say not always needed) but when an older boat, say a 1982 built boat, was epoxied in 1990 is there likley to be a common recurring theme/reason for this and is it a big benefit on a used boat?

 

[oldharry]

Assuming we are talking GRP here, and not timber treatment? The usual reason for an older GRP hull to be epoxied is Osmosis cure or prevention. Once the damaged gel coat has been removed, it is replaced with the much tougher epoxy, which is (supposed!) to prevent further problems.

Epoxy sheathing a 10 year old timber hull is potentially very dodgy indeed, and is often done to botch faults in the original timber as an alternative to a proper repair. But not always: - It often needs an expert to tell the difference between preservation and botch!

 

[oldsaltoz]

G’day David.
I had to give this one some thought as blistering after only 8 years is not common, though not unheard of.
Removing 8 year old gel coat below the water line and applying an epoxy coat is not something you would do “just in case” you might have a problem later; this is an expensive exercise. It sounds more like the 8 year old gel coat failed. The fact that is has been treated is good and bad. Good, because it would have prevented further damage to the laminate. Bad, because it needed treatment so soon after manufacture. As with any purchase of a used boat, get a surveyor in and make sure he has as much history as possible.

Avagoodweekend Old Salt Oz……

 

[david_e]

Thanks for the replies, the boat(s) are or would be GRP. I suppose this answers my thoughts/query which is that if it has been done after 1st launch then it is most likely to rectify a fault, suppose with each boat the story will be different boat. Question is whether or not it is a major problem, people sell it as a feature which still has me wondering why?

 

[castaway]

The question is whether the gel coat was removed prior to the epoxy job, in which case it was to cure a problem, which is rather early in our cold UK waters. Or if someone has simply cleaned off prepared and epoxied a perfectly good and sound bottom as a precautionary measure.

If its the latter and it all looks good and sound then all should be well, and you have a bonus. The difficulty is is finding out which it is... Regards Nick

 

[Guest]

One of our most respected osmosis experts says (if my memory is correct) that 80% of 10 year old boats surveyed by him exhibit some signs of osmosis.

I have seen several second hand boats stripped back to the gel and then epoxied by new owners who either ignored signs of osmosis, or kidded themselves that what they saw wasnt important.

 

[oldharry]

The reason people quote the 'repair' as a sales point is that it is time consuming and expensive, and the end result is claimed to be better than the original.

In other words - the works already been done, so you dont need to worry about osmosis any more!

Pity its not a pefect world..... And if epoxying IS as effective as the suppliers claim, why is it not done as a matter of course to new boats? The additional build cost would be a fraction of that of 'retro-application' ( no drying out period, no stripping of original gel coat etc) - yet 'cost' is invariably the reason given for NOT including an epoxy coat at the build stage.

Any comments?

 

[david_e]

Your point seems logical and well made, the only counter point I heard from a Beneteau dealer was that the modern composites are much better than those of yesteryear and so don't need epoxy treatment. Is this true.......?

 

[Chris_Stannard]

A small point but if the boat is epoxied from new the coating is said to last eight years. I do not know if this has a bearing on boats where this is done as a cure for osmosis.

Chris Stannard

 

[billmacfarlane]

I've heard that story as well David , and frankly doubt it. The dealers might well say it as part of a sales pitch but my understanding is that modern gelcoats , the ones that use iposphalic resins are still not 100% waterproof. Even with boats built with these resins , it's advisable to use an epoxy barrier though I've been advised that if you're thinking of getting it done to a new boat , you're best waiting for 2 or 3 years , the reason being that that it allows time for any uncured styrenes to evaporate before you apply the epoxy.

 

[david_e]

Will you be getting your Maxi done in a few years Bill?

 

[billmacfarlane]

Yep . nm

ddff

 

[david_e]

ddff

..can't work that one out.

 

[vyv_cox]

My 1985 Sadler was professionally coated with Gelshield 200 in about 1993 after high water content was found. It looks to me as though only two coats were applied. No further osmosis problems until last year, when some blistering was found. Taking advice from International, over this winter we stripped all antifouling and some of the Gelshield 200, then recoated with three coats. However, our experience does support the suggestion that Gelshield 200 coating lasts around 8 years. But note that the latest International leaflet talks about 6 coats.

Gelshield is a different matter, normally used to replace gel coat after grit blasting the old stuff off. This has no solvent carrier and could be expected to be more impervious to water. Its dry film thickness is higher than that of Gelshield 200. I would expect to get 15 years at least.

All timing is dependent upon various factors. My boat has been mostly in fresh water, increasing risk of osmosis, without wintering ashore for the past five years, also increasing the risk.

 

[david_e]

Thanks vyv.