you could make a decent boat brush out of the home depot catalog...
16 ft of 2" plastic pipe
can of pipe glue
one or two - 2" plastic pipe elbows (depending on boat hull)
one 2" plastic pipe "tee"
3- 2" plastic pipe end caps
3 cans of spray foam
1- astro-turf floor mat
hacksaw and at least a six-pack of your favorite beverage
I'm going to assume you know how to glue plastic pipe
cut 2 pieces of the pipe 16" long
put one end cap on each piece fill with foam, attach each piece to the "tee". again, fill with foam.
cut another piece approx. 36 inches long (this will depend on how wide your boat is) place into "tee", fill with foam.
depending on your dock space and the design of your hull, you'll either use one or two 45 degree elbows.
finish off the handle, and fill with foam.
cut and wrap the astro-turf around the business end and tie wrap in place.
The foam will give it some "upward" pressure, so you lazy or crippled twits can get decent results.