Wayne.B wrote:
On Sat, 22 Jan 2005 11:23:47 -0600, "Sail-n-Dive"
wrote:

I really left the Paceship in too long this time and have a fair amount of
barnacles. I've done many bottom jobs and have never tried to get every
last bit of the barnacle off as long as it was relatively smooth. For a
hull speed boat, I can't see the harm. I'm using a very high quality
ablative bottom paint this time and want to be sure that it's a lasting job.
Any INFORMED comments?

===========================

I had ablative bottom paint on my small boat and had good luck
removing marine growth of all kinds using a standard Mark I, Home
Despot pressure washer (~~$450 variety). Of course it also removes
most of the bottom paint, at least the ablative active ingredients,
but if you're getting ready to repaint that's not a problem. I've now
gone to a hard paint with a biocide in it that seems very effective,
believe it's called Micron Extra with biolux slime blocker.



It "does" matter & probably even more so with a displacement hull, so
getting all the old barnacle off is worth the effort, although granted
it's depressing job:-)

Get all the old loose paint off with a water blaster as above, then
scrape all the barnacles off.

As you are obviously aware, it's difficult to get the base of well
established barnacles off with a scraper & not cut into the underlying
paint so it's best to give the whole bottom a "quick" sand with an
orbital sander.

So long as you water blasted all the old loose or soft antifoul off, it
shouldn't clog & you'll quickly see which grit of paper suits the
surface (use as fine as will not clog but still knock the high spots off
the existing paint). You're not trying to remove or even sand through
the remaining paint, just flatten the surface & rough it up a little for
the repaint.

When you come to a barnacle base left after the scraping, just slow
down on that till you sand it away, they're hard & orbital sand off
pretty easily.

If you're changing to a new style of anti foul say going to soft
ablative from the harder types then; when it's sanded smooth & surface
slightly roughed give it a couple of barrier coats & another very quick
light sand before the anti foul.

Wear a mask when sanding antifoul even if there doesn't appear to be
much dust.

K