Re: Advice on Best Antifoul Paint that Holds Up -- In & Out of Salt Water
A lot depends on the precise location and the nature of the 'fouling properties' of the water in which you keep your boat. Keeping the boat in the 'still' water behind a bulkhead, or at the 'head' of slow moving stream/creek invariably will allow a LOT of slime build up, quickly followed by the growth of 'hard' fouling, sponges, etc. that will get a 'foothold' in the slime. Usually, you have to find out which type of paint, how the locals apply the paint, etc. ... and then 'match' the type and method for the area where you keep the boat.
With long haul outs interspaced with 'in water', will exclude all paints except ablatives, ablatives with 'slime' additives, OR straight teflon/copper (VC-17, Baltoplate, etc.).
With case of ablatives and ablatives with anti-slime compounds you can 'dry' and launch repeatedly with only little loss of 'protection', sometime all you have to do is very light sanding to expose 'fresh'.
Over the (many) years Ive found that the least amount of ablative (with anti slime agents) that you can apply and the 'smoother' you can apply the ablative when needed, the longer it will last and the less 'build up' you will get ... ablative build up to excessive thickness usually results in the 'deeper' layers ultimately failing and losing their adhesion .... and you get 'flaking' and undue 'roughness' of the bottom paint.
A smooth application (racing bottom quality) will also allow easier and quicker 'release' of the inevitable slime build up when the boat gets up to near hull speed. The less amount of accumulated slime the less ability of 'hard' growth to become attached, the smoother the bottom paint the easier the 'release' when sailing or even when 'wiping' the bottom occasionally - I just use a rubber 'squeegee' every two weeks. .... at least thats what Ive found to be the case from the Canadian Maritimes all the way down into the Carrib.
First, for high quality ablatives (I favor Micron-Extra) Id recommend a 'hog down' of the existing bottom paint to keep the thickness to a minimum, the first coat with a 'contrasting' or tell-tale color, followed by a (WEST yellow) foam roller applied 'base coat' of ablative. Use of thin foam rollers to apply the FIRST (or and/or second) working coat will keep the 'roughness' down to a minimum, the rougher the previous coat the more expensive ablative you have to apply later. When the FIRST color coat is 'almost' hard/cured, then take a large polyethylene trowel (the yellow WEST trowel are good) and knock the tops off of all 'roughness', dribs, etc. ... forming little square top 'mesas', then let fully cure for a week or two.
The finish coat is by using a thin foam roller to 'deliver' the paint to the previous coat and the finish coat simply fills the 'valleys' in the first coat ... apply the paint with a roller in 'stripes' and 'push' the paint into the valleys with the poly trowel .... the stripes will be applied with 'spaces' inbetween the stripes. (This is how you do fiberglass finish work on a male 'plug mold'). Let the smoothed-out 'stripes' fully cure/harden and come back a week later to fill in between the 'stripes' using the same method. The result won't produce an absolutlely smooth and fair racing bottom but will be close enough; but will be significantly smoother than paint 'slopped on' with a hairy roller.
When later hauling the boat if the 'contrast color' is starting to show through only repaint those zones that are 'showing' through .... the contrast color 'tell tale' coat is also ablative and should have the same 'potency' as the 'finish' coats ... and you 'can' delay the 'repaint' for another season if you desire.
You may need to re-fill the 'valleys' and developed surface roughness yearly, but this will only need 'quarts' of bottom paint instead of horrendously expensive gallons. And by only using 'quarts' to do the 'fill' of the surface roughness that develops you dont get the inevitable 'mass flaking' when the deeper applied layers ultimately lose their adhesion.
In the Carolinas and Georgia, the practice of using anti-slime ablative paint for 2-3 feet down from the waterline (the SLIME ZONE) and just plain old 'ablative' lower than that is becoming common ... to help keep the cost down.
So, in summary, use what the locals are using; but., put it on as smooth as possible, and keep your boat in 'flowing water' to keep the slime to a minimum - the least slime build up the least amount of hard growth.
FWIW, in areas of heavy 'hard growth' use "Prop Ppeed' or Petit Zinc-Rich "Barnacle Barrier" on all the metal underwater gear.
If slime is a problem ... get a retractable painters pole and attach either a squeegee or attach a few square feet of 'Berber' carpet and simply 'wipe' the underwater surfaces every week or two, dont needlessly scrub the ablative paint off. With a 'smooth' bottom you'll remove most of it, just by 'wiping' the hull. Usually no need to 'scrub' which also removes expensive bottom paint ... and least amount of bottom paint that unnecessarily goes into the water the better from a 'conservation' stand-point.
Hope this helps.
Last edited by RichH; 11-14-2012 at 12:44 PM.