Mark

It depends on several factors - type of antifoul, hull material and why
you want to remove it.

On a wooden hull with a (soft) ablative type of antifoul we do the
following:-

ANNUAL ANTIFOULING: High pressure water blaster to remove all
barnacles, weed, slime and loose antifoul. By the time the growth has
gone, so has loose antifouling. Then then just paint over the top - No
sanding needed.

SEVEN YEAR BUILD-UP; About every seven years we scrape the antifoul
back to the paint primer using a tungsten scraper with a long handle.
We literally put a broom stick on the scraper as we find the longer
handle allows you to apply more and better contolled pressure. Once
scraped, we go over entire hull with course sandpaper in a random
orbital sander (Good face mask needed). Then we reapply paint primer,
undercoat and two coats of antifouling.

Hope this helps.

Graeme
sv Leonidas