Frank
I remove the antifouling build-up frm my yacht every five or six years,
and this is what I do.

First wear protective clothing including a good carbon-filter mask or
positive pressure mask, as antifouling paint is quite toxic.

Next use a tungsten blade hand scraper. I find I have more control if I
put a very long handle on it - litterally broom-stick length. This will
remove the paint build up surprisingly fast but at the expense of a lot of
muscle power.

Finally finish off with an electric sander. (An electric sander is far
slower than a hand scraper in removing any deep build-up). Then apply new
paint system.

All waste must be collected and disposed of properly and legally as its
still toxic, and depending where you are there may be federal, state and
local laws.

While doing all this remember that antifouling paint is a POISON
deliberately applied to the bottom of a boat. If it was not a poison it
would not work.

Fair scraping

Graeme
sv Leonidas