I think that thing (and/or maybe the girl) is designed to catch the person, not do much of a job.
It has been estimated that a fouled bottom can reduce a ship's speed by up to 10% using as much as 40% more fuel to compensate. SeaRobotics, with funding from the U.S. Navy Office of Naval Research (ONR), has come up with an answer to this problem.
May I then present you with...
The ultimate in underwater grooming.
The "HullBug." Fully automated, robot attaches to your hull with vacuum technology and moves around your hull cleaning and anti-fouling.
I couldn't find an exact price with shipping, but I think it is a little more expensive than the Goby Hull Cleaning System. So, be prepared to layout more than a few Boat Bucks. I guarantee there will not be a single lousy rash bump involved when you clean your bottom with the HullBug. The best invention since Bag Balm.
AND, if you order before midnight tonight, We'll throw in a set of Ginsu steak knives, ABSOLUTELY FREE.
-Will ( Dragonfly)