What primer for the hull? (Half used tin list from my store, some domestic)

[HandmadeMatt]

Hi everyone.
So, I have a plywood hull. It was caked in mud from 17years of living in a creek (Ashlett.)
Lots of Jet washing, scraping and sanding later I've removed all the mud, substantial amounts of the last antifoul and in some places some of the primer back to the ply. I have removed all loose material.

Before:

After:

I intend to patch up the primer, in some places small spots and in others larger coverings. This is all in preparation for the coating of new antifoul.

I have these primers, which ones can/ shall I use?

First choice:
It claims to be for below the waterline. Ideal, although it's a small tin and only half full.

This claims to only be for above the water line, it might be OK under antifoul though?

This looks like really good stuff to use on the metal fittings, rudder hinges, prop etc:

These two are domestic products, not specifically for marine use but might be OK?

the antifoul that I'm using is this stuff:
HERE

Ideally would I be best to cover the whole hull in primer before the new antifoul? (This is why I am considering all these products that I already have on the shelf.) If I have to go out and buy new primer I will but I don't want to waste money.

Advise welcome. Thanks.

 

[William_H]

Nobody seems to want to commit to answer. I would use the first can I think. The Lakes is an antifoul made for Ali comp[onents so no copper so proably only good for Aliu sternd rives and O/bs left in the water. Probably all the others OK for slapping on. good luck olewill

 

[Bobobolinsky]

I'd use the International domestic primer, but do a test with antifoul first, to ensure that they are compatible. My experience is that some coatings don't adhere to it

 

[Pasarell]

With apologies to those who have already replied, ignore what they have said, and don't use any of them.
International Metallic Pink Primer was the primer for wood underwater. I expect the name has been changed, and probably the formulation as well, but get the replacement for it, or the equivalent from Blakes or another good marine paint supplier. You will need at least 2 good coats, possibly more but look at the instructions first and follow them. This will be the most important coating you apply. Don't use the tin you already have as it looks pretty old and, being opened, will have gone off.
Your 2nd photo, Int Yacht Primer, is not suitable for use below the waterline. It will blister and allow water through the coating and into the wood.
Blakes Lynx Plus is an antifouling, not a primer. Very low strength so probably not suitable unless you are staying at Ashlett and the boat will dry out each tide
4th photo is a water based compromise product, suitable for exterior use at home but not for a boat and definitely not for under the waterline.
The Toolstation product is possibly OK but I would not risk it. The instructions you can see say for general exterior use and, combined with it being white spirit based, suggest it is not suitable for immersed use. Again I would expect it to blister and detach from the hull surface.

I would recommend a good rub down with 80 or 100 grit paper (if you haven't already done it) followed by at least 2 coats of a primer designed for underwater use. Anything else will be a false economy.

 

[HandmadeMatt]

Prime the whole hull then? Not just touch ups of the exposed wood area and small metal area on the rudder hinge?
Primer on top of the old antifoul?
I have already jet washed, scraped and then rubbed down with 60grit.

Is the primer the barrier for the wood then rather than the anitfoul?
Thanks everyone.

 

[jwilson]

I agree with Passarel. The hull looks at a glance sound so keep it that way, and the most critical thing with ply hulls is a) to keep water out of the outside of the plywood, and b) to keep water out of the inside of the plywood - ie the bilges. That means good quality waterproof primers, followed by topcoats of undercoat and then gloss. The ply under the paint must remain dry, or it will rot.

The key coat is the primer - it is what binds the wood surface to the undercoat and gloss coats, taken together they form a barrier to water. The antifoul is not usually very waterproof: it is there only to stop weed and molluscs attaching themselves and wood-boring crustacea eating the wood (though they don't like plywood much, there will be some actual treewood in places).

Choose a manufacturer and read their tech data and buy some new marine paint - at the very least for the underwater parts. You can get away with good quality (high VOC marked on can) oil-based domestic paints for the topsides and interior, though a marine product will probably last better. Nothing where it says "clean brushes with water"...

 

[LittleShip]

Primer is indeed what will protect your wood, anti foul is permeable and has no effect on stopping water getting through.

If you can find it ...... Red lead is good but, I use international Primocon on Little Ship as she is wood also.

If you want the best job..... Clean it all back to wood and apply a couple of coats of epoxy, that will completely seal the wood from water ingress...... but expensive.

Done correctly it will last for years, done quickly ( poorly) you will be doing it again next year. Perpetration is 80% of the work, slapping paint on is the easy bit.

Tom.

 

[HandmadeMatt]

Brilliant. Thanks again. I'm sold on doing this properly.
I'm going to undercoat the whole thing with a good product and then antifoul. I'm off to Titchfield boat jumble today, maybe I'll get a bargain!
No need for a gloss coat I don't think. A grey primer, then a red antifoul is what was there before and she's lasted 50years already!

 

[Tranona]

Suggest you follow the recommendations of a paint manufacturer. If you are using International the correct primer for underwater and under antifouling is Primocon, NOT Metallic pink, which is for above water. Would be wary of wasting my money on an unknown brand of antifouling off eBay. For a bit more money you can get a recognised and proven brand. One thing you will discover with your boat is don't skimp on the finishes - use the proper stuff. Hempels and Epifanes will have their equivalents and all will provide good information on what to use for each job and how to apply it.

 

[HandmadeMatt]

...NOT Metallic pink, which is for above water.

I hear you in general and have decided to prime with a good primer but on the tin of the Metallic Pink it does say for above and below the waterline.

After taking on board everything everyone has said I intend to patch prime the exposed areas so they have extra coats, then prime the whole hull and finally anitfoul it. Comments welcome.

 

[HandmadeMatt]

I went for a Blakes/ Hempel primer. I thinned it a bit and it's gone on a treat. The second coat will be dry by midday and then the anitfoul will go on this afternoon.
Doesn't it look lovely?
Thanks everyone.

 

[HandmadeMatt]

And there we go, first coat of antifoul. What a difference! What a feeling.
Next the blue is all going dark navy blue and the yellow is going pale cream. Finally all the top side wood and then she's good to go!