Hull Cleaning IN the water?

[rgranger]

...The easiest way to remove the growth above the water line is with a mild acid.

I have found barkeeper's friend works very well for the brown line above the water line. It is mostly oxalic acid.

 

[jdhohmann]

I've tried several methods to do the cleaning of hull while it was in the water, nothing really worked. The bouyant properties of water makes it near impossible to clean the hull adequately. Ive seen this product a few years ago, i bet it works awesome...

Henderson Marine Supply