primer or Epoxy after scraping bare

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prigollet

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Having a 9 year old boat where the antifoul was scaling off in patches I decided to take on the job to get the boat bare. So I scraped and removed everything to the gelcoat and now in the process of sanding the rest.

Now comes the question of whether I should put a primer like Primocon or should I put an Epoxy. After reading about Osmosis, it seems that putting an Epoxy like GelShield is only worth if the boat is dry (i.e. low hull humidity reading).
Given the boat is 9 year old, the hull wouldn't be completely dry. And here comes my problem. Am I better of putting a primer which I believe offers some waterproofing or should I epoxy and do more bad than good because the hull might not be dry enough.
Second problem is outside temperature. I would need a few days above 10C night and day.

Any advice out there?

PS: Has anyone used this brand of A/F http://www.shepherdmarine.com/seaforce-30 Never heard about it before today and quite a good price

thanks
Philippe
 
Just had our boat gritblasted removing very thick antifoul layers down to Blake's epoxy with which it was refinished after peeling 14 years ago. The blasting blew a few little holes in the epoxy presumably where it hadn't adhered well, and there were some not very good patches where cradle pads had been when the peel was done.
We applied several layers of Jotun Penguard HB epoxy primer which builds well, and epoxy filler where necessary.
Covered this with Jotun Vinyguard waterproof bonding primer. This goes on very nicely and forms a thick tough film with one coat.
On top of this we used not Seaforce but the more expensive version Seaguardian. The weight of a 5l can of this is amazing. It flows on beautifully on top of the Vinyguard and covers well with the first coat. We did 2 coats on a 29 footer and have a little bit left.
She goes back in tomorrow so I won't be able to comment on the antifouling properties for a while, but from an application point of view, I'm very impressed with all these Jotun products from Shepherd Marine. They seem very good quality and a huge saving from SeaJet which we intended to use and then our gritblaster suggested Jotun.
You can use their epoxy down to 2 degrees with low temp additive, the Vinyguard and antifoul are OK to 0 deg I think.
The guy at Shepherds is very helpful on the phone too, worth phoning for his advice.
FWIW I suspect if the gel coat is sound I would just use the Vinyguard not epoxy - but don't blame me!
Oh, use a roller not a brush for a much nicer finish, and hairy works better than foam. The HB epoxy affects the foam ones anyway after 10 minutes they go all swollen and floppy!
Mike
 
Willow I've just bought the penguard and the primer from malcolm (really nice bloke) after your last recomendation, 5 litres of penguard + hardner+ thinners and 2.5 litre of primer although i'm using international A/F. Just waiting for a decent weekend to apply the stuff now. Any other tips apart from not using foam roller's with the penguard (drat just bought some for that purpose).

Sorry for highjacking this post but if you have any tips that might help me it would be most helpful.

Thanks
 
Unless you can take meaningful moisture readings stick with a single pack alluminium based anticorrosive like Primocon or its Marine equivilent Intertuf JVA200 series, very similar to Jotun's vinyguard, as it does allow a bit of flexibilit.y Epoxy on a dry gel but damp laminate will only blister and I know what I would rather remove if Osmosis treatment was ever called for!!
 
Sorry can't really add any more. Still not sure I would use the epoxy, tend to agree with Grajan 1, but it's your boat, your choice! I presume it's what Malcolm recommended.
Mike
 
Oops sorry mixing up two posters! Don't know what you are working on Aidy so delete comments about epoxy intended for PhilippeR.
Can't see why you are using International a/f on top of it. Why not be consistent with one or the other!
Mike
 
May I suggest (contrary to other opinion) that as you have completed the worst part of the exercise /forums/images/graemlins/smile.gif that you consider an application of VC Tar. On my previous vessel, at about the same time period, carried out the same process....7 years later when sold..moisture content in hull was significantly lower than normal! /forums/images/graemlins/smile.gif It is easy to apply and gives peace of mind! might be worth having a look at the spec sheets. HTH
 
Thanks all for your answers!

Talking to the yard who had prepared the boat the first time and asking what they had put. The answer was they usually put 2 layers of hard AF. The explanation was that hard AF gives some AF protection and gives a better smoother finish than primer.

So now not 2 sure what I will do. More tempted to simply put primer.

As I was sanding yesterday, I also found 2 cracks in the gelcoat. Can I avoid repairing them and put the primer? Since primer will prevent the water ingress.

cheers
Philippe
 
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