Join Date: Jul 2000
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Re: Bottom paint advice needed
If you 'get down' to barrier coat, you'll need to 'roughen' it - 100 grit is the choice, just roughened to provide sufficient 'tooth' for the new paint, dont deeply 'sand' into the barrier - especially if you dont know the original lay-up thickness of the barrier.
If the OEM barrier is found to be 'rough' (very pimply) as when applied with a shaggy roller, then consider to 'fair' the surface with epoxy + micro-balloons, etc. before applying new paint.
If the boat was 'hot coated' - bottom paint applied over partly cured barrier - then Id suggest that you also scrub with HOT water to remove any 'amine blush' that formed during the 'curing' of the barrier. Since you dont know, Id suggest a HOT water scrub then 'roughen'.
Boats that are 'hot coated' are more prone to such 'flaking' of their ablative bottom paint later on - just my suspicion.
You dont want to do this job 'twice'; now and several years again in the immediate future.