Gelshield, or not?

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RadiumRob

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My (new to me) 28 year old yacht underwent full osmosis treatment in 1994. This involved gelcoat removal, laying up a layer of biax cloth, then epoxy coating.

I have just has around ten coats of anti-foul removed by blasting (Farrow) and the hull prepped ready for painting. The hull condition appears to be very good, and there are no blisters or signs of wicking.

I am contemplating treating the hull with Gelshield 200, but am apprehensive, my fear being that the application could go wrong (fail to cure, hull too damp, temperature too low, general incompetence etc), and I would end up busting something that doesn't need to be fixed!

The pre-purchase survey indicated very little difference in moisture levels between topsides and below the waterline.

Any advice welcome...
 
A tricky one. I was in a similar situation some years ago and got a local yard to stick a moisture meter in the hull in a variety of places once the boat had been out of the water over the winter. They concluded that it WAS dry enough to be worth putting some Gelshield on.

On the one hand, it doesn't sound like it's necessary. On the other, now that you've had it blasted, you're probably never going to get a better surface on which to apply the stuff!
 
QOUTE=RadiumRob;4091686] Any advice welcome...[/QUOTE]



Did almost the same job as you 3 years ago and it is not exactly rocket science!.

Now you have had the hull blasted it would be crazy not to protect the hull and your investment,the two key things is Day tempreture (min 8 deg C , better at 10 deg) AND the night tempreture (min 5 deg).

If you use Gelshield 200 also clean down with International thinners no 7 to clean the hull and then wash off with clean water and leave to dry.

I also used Gelshield 200 (applied 5 coats) then 1 x Primocon then 2 x Micron Extra) and was very pleased with the results and after being 'in' for two years just had to power wash off slime when I lifted 'out' last December.

My tips are let the two pack stand after mixing correctly for a few minutes to get rid of any air bubbles and DO NOT mix it all at once , mix as much as you can apply in say 20 minutes, I used a 100mm foam type roller which you can buy a 10 pack from B & Q.

However I am also helping my mate do do his boat and this time we will apply Jotun Penguard HB http://www.smlmarinepaints.co.uk/primers/two-pack/penguard-hb
which as you can see is much cheaper and you get much more (5 ltr cans), we checked the specs like for like and we see very little differance to the Gelshield 200, we will apply 4 coats, then 1 x Jotun Penguard 88 primer http://www.smlmarinepaints.co.uk/primers/single_pack/vinyguard-silvergrey-88 then 2 x coats of Jotun Seaqueen antifoul.

We are both happy about using International Gelshield 200 but due to the BIG cost savings went for the Jotun system.

Happy painting

PS: I do not work for Jotun as now retired, just learnt things by experiance :D

Mike

First coat of Gelshield 200
 
Thanks - that's quite a saving with Jotun. At that price I'm very tempted but I can't help worrying that it doesn't do something that Gelshield does though. Has anyone got long-term experience of Jotun?
 
Your hull has been stripped back and rebuilt again but using Epoxy glue, so why would applying Gell Shield, another Epoxy Glue, give you further protection from moisture ingress? Is the porosity and permeability of Gell Shield significantly less than the Epoxy glue your hull has been rebuilt with? If it's not, then don't waste time and money doing it.
 
There are strong arguments for NOT doing it, as BOB has said. However whilst staying away from that argument, I will say that Gelshield is very easy to apply, having used it on my old Jag 27.
I have just had the old antifoul stripped back (gawd, getting lazy...) and the hull prepared on my new to me, 13 year old Feeling 286. Whilst I appreciate that modern resins and gelcoats (isopthalic?) are more resistant to water ingress, it seems almost churlish to me, NOT now (having been so prepared) to apply an epoxy shield, as there was none, and would also provide a barrier in future a/foul removal. To whit I have bought GelProtect, which is a non solvent based epoxy (GelShield is solvent based) I wouldn't know if one is better than the other, but GelProtect is less tolerant to temp. when applied.
 
BlowingOldBoots said:
Your hull has been stripped back and rebuilt again but using Epoxy glue, so why would applying Gell Shield, another Epoxy Glue, give you further protection from moisture ingress? Is the porosity and permeability of Gell Shield significantly less than the Epoxy glue your hull has been rebuilt with? If it's not, then don't waste time and money doing it.
Click to expand...

That's one of the reasons for my uncertainty - the original repair appears to have been very effective, so I am worried that I could compromise it by applying something to it. If the do-nothing approach is viable then I would very much like to take it. And spend the money on a rope-cutter!
 
Strong advice from the yard who look after my 34 year old boat is to NOT epoxy coat old boats. It's counter intuitive but they are insistent and refuse to do it for clients. The reasons are that it can and will blister, once it has it's a nightmare. It's harder than your gelcoat and will be an absolute buger to get off without badly damaging your gelcoat. Then there's all the research to show that the pesky water molecules happily get past the epoxy coatings and that the osmosis is determined by the quality of the original manufacture. The Kipper hasn't got a trace of osmosis except some pinhole pops along the waterline where the drying water causes problems for lots of boats. 34 years and the hull is blister free, contrast that with boats less than half the age who have had extensive osmosis treatment - it's not age it's original construction. Now that you've got an epoxy barrier why add an expensive additional one that if it goes wrong will cost you thousands to put right?
 
Lazy Kipper said:
Strong advice from the yard who look after my 34 year old boat is to NOT epoxy coat old boats. [...] Now that you've got an epoxy barrier why add an expensive additional one that if it goes wrong will cost you thousands to put right?
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I'm with this, any "treatment" put onto gelcoat may be problematic as problem lies underneath. So anything put onto blistering hull will get blisters below it, sure.

But OP already has epoxy treatment and the proper one in fact - layer of new laminate, glass-epoxy put onto clean hull laminate, not onto old gelcoat. This is as good as the rest of laminate.

Well, it's not about GRP hull, but epoxy coatings on steel are considered to deteriorate with time (15-20 years useful life) so after some time they should be painted with a fresh layer to prolong their life.
As OP's is about 20 years old - and surface prepared - why not refresh it? Two layers at least of paint so to have proper covering made, no voids.
Not that it's necessary, maybe not, but protecting material with paint is normal way to do things...

Edit - just in case: I'm speaking about paint, not making some "covers". Something like putting on good surface primer before antifouling. This is only to seal some pores or microcracks in the surface and renewing it chemically.

As for failure of coatings - 40 year boat, bottom painted with epoxy paint (VC kind) twice - last time about 10 years back, first - who knows, but probably another 10y back. Paint seems all right, keeps, just few small blisters to touch up. But gelcoat below this paint is real mess - painting was probably done to seal cracks in it and seem to do the job. At least scraping the antifouling is possible without getting the gelcoat off as well ;)
 
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I to have used Jotun penguard HB on the topsides of my last boat before we did the two pack PU. It is very good.
We recently have used the Jotun to prime the cockpit. The temperature in the shed we are in last weeken was 6 deg C and the Jotun wnr on ok with a little thinners. It cured very quickly. Just as soon as we had finished we were able to get a second coat on. It's good stuff
 
Rossynant said:
.... but epoxy coatings on steel are considered to deteriorate with time (15-20 years useful life) so after some time they should be painted with a fresh layer to prolong their life. ....
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There are epoxy built timber boats in excess of 30 years of age that have sound timbers and still remain strong. Tenacious, the Jubilee Sailing Trust's three-masted barque is a wooden ship built using Epoxy. I believe that her hull design is certified by Lloyds as having a 100 year life (obviously with appropriate maintenance but I doubt that involves ripping all the joints apart and re glueing).

I am not doubting or challenging your epoxy/steel claim, however, there are cases of epoxy having a long life, at least with wooden yachts from what I can tell.
 
Epoxy as such is long lived - this is about covering, paint systems surface gradually getting damaged, cracked, or eroded etc. Refreshing the surface never hurts, i'd say :)
 
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