Bottom Coatings

I'm after suggestions about bottom 'paint' for the strip-plank / epoxy hull that I'm building at the moment. It's a 28ft trailerable boat that is likely to be left in the water for up to a week at a time.
I'm told that the 'normal' polyurethane paints - awlgrip and the like - don't like to be immersed for this amount of time.
I'd prefer not to antifoul the boat, and the only epoxy coatings that I know of go yellow with exposure to UV.
Any suggestions?

 

keep it gel coat,,,,,but you do know what happens to a boat without antifoulin paint right?

 

There is a BoteCote epoxy product thats heavy in copper, sort of a permanent anti foul that you can get a good finish on.

http://www.boatcraft.com.au/paints.html

 

never mind,,i reread,,i see its epoxy,,,,

 

Well good finnish for an antifoul!... that is.

 

I have done a few trailer sailers that way with a 400 grit wet sanded finish. The epoxy does not chalk that fast on the bottom. The polyurithane paints will buble and blister usualy within a few days under water "done that". VC under water epoxy works great for that if its available, I did one with it 10 years ago and it still looks good
Tom

 

If the boat is only in the water for a week, there is certainly no need to antifoul. Barnacle pips only become solid after about two weeks. A light rub dowm with a doodlebug would certainly clean off any slime of crap that may start to grow. Do not use polyurethane, it will blister.

the Bote Cote type product is quite OK, if you have a nonferrous merchant in your area you can also use their cut off filings and make a mix from this, just put it through a fine s/s sieve first.

 

Thanks guys
Yes, I'm familiar with the coppercoat system. We've applied it quite successfully to another boat about 4 years ago and it's still going strong. The only problem is that I'd prefer a white finish and the coppercoat goes a rather unsightly dirty blue-green, particularly around the waterline. It's also very heavy.
Tazmann - I assume you're referring to the Interlux VC epoxy. Looks interesting, though a quick browse doesn't show it as being available in Australia - though I'd be surprised if it's not. It's more the sort of thing I'm looking for...

 

Truck bed liner (Rhino Coat, LineX, etc.), There are two versions, one is a very fast drying spray on polyurethane, the other is slower (but still quite fast) intended for rolled applications. The fast (spray version) is about like an aerosol version of 3M 5200. It's extremely tough, moisture proof and sticks like no ones business. The roll on stuff is slightly less tenacious, but still very good. It's often sold with polyurethane or rubber beads in it for texture (which can be strained out).

 

Bloody hell Paul....that sounds a bit agricultural! But as a polyurethane, how well does it stand up to 'prolonged' underwater exposure?

A little exerpt from the Interlux spec sheet:

Sounds like a possibility... thoguh I wonder about the teflon content... whether it would effect adhesion of any future coatings - like antifoul if the boat was no longer trailered for instance...

 

can it be used as barrier coat also???

 

Just use Interprotect white, it will do the job nicely

 

My understanding is that interprotect is primarily intended as a barrier coat and is normally overcoated with antifoul. That's probably not strictly necessary, but it is subject to discolouration from exposure to uv

 

Will
Yes it was the interlux VC underwater epoxy I was refering to.
My 26 that I am finishing up I am using Macro poxy 646 from sherwin williams, comes in black or mill white, suposed to be an afective berrier coat when you dont add any pigmintation "color" , seems to be close to the VC epoxy without teflon. My other boat that I did paint with VC I left in the water over one winter 5 or 6 months, when I pulled it out the bottom looked pretty nasty but it cleaned up with a little elbow grease and the paint was in perfect shape.
The copper coat that some are refering to I did 2 bottoms with, If I remember correctly it was called copper poxy here, nice stuff holds up well but the color does look a bit nasty after a while, little wet sanding brings it back to the original color. Not an option here anymore "outlawed"
Tom

 

I've been doing some testing for one of the major truck bed liner manufactures and it is non-fouling, so bottom paint isn't necessary. You can have any color you want and it's very tough. It's sticks extremely well to typical boat hull materials. Some boat trailer manufactures are coating their metal with the stuff as well as it's many other uses.