Andina Marie wrote:
Suction cups don't work - if they did the bottom wouldn't need
scraping.
The suggestion of using a hookah unit is good - I've spent as long as 5
hours underwater scraping our bottom without surfacing. The freedom of
diving without the tank(s) is also an advantage.

One trick is the kind of scraper you use. It has to be HEAVY. I use a
cold chisel - it has a steel handle about 1" in diameter (hexagon or
octagon?) by 15" long and a blade about 4" wide and 1/4" thick. The
advantage of this scraper is it has its own weight, its own inertia.
If you use a conventional paint scraper you are relying on the mass in
your arm to push the scraper through the barnacles and that continual
shock will make your arm very sore very rapidly. With the heavy cold
chisel it absorbs the shocks as it bumps the barnacles off.

Ann Marie

I reccomend an old fashined edging tool. Basically, it has a long
handle like a shovel and a is like a hoe without the bend.
Essentially, its a very large paint scraper. It has enough mass to
work as the above poster describes. You will also need a short handled
scraper like a very heavy duty paint scraper. The problem I have is
that I have dropped my tools into the muck below the boat and lost them
so use a loose lanyard on them.
With the long handled tool, I can anchor in water with some vis and
snorkel around the hull and get all the barnacles off.