On and Off works great, but before you use it make sure to get the boat
off the trailer and set up on blocks because any you spill will eat
away the metal of the trailer. Flush it off with a LOT of water before
putting the boat back on the trailer.
Wayne.B wrote:
On Sun, 12 Mar 2006 15:24:57 -0600, (Gudmundur)
wrote:

Hi Folks,

I have just a small 15ft fiberglass open bow ski boat. I am it's
second owner, and the first owner left it in the river about 8 months
every year. Problem is he never cleaned the scum and grime from the
underside. The whole bottom of the boat now feels like 80 grit sandpaper.

I realize cleaning this mess up won't be easy, but can anyone recommend
a good cleaner to help remove the scale? I thought the fiberglass was
actually damaged but that does not seem to be the case. My trailer has
bunks without rollers and I have found that the areas that slid on the
bunks are scale free, this includes the recent areas where I hit the bunks
a little off to the side.

As scaled up as the bottom is it would seem I may be losing a few MPH
on the top end. It will be interesting to do a before/after speed check.

West Marine sells a product called "On and Off" which is a powerful
acid based formulation that is as close to a miracle cleaner as
anything I've ever seen. Read the directions carefully, wear rubber
gloves and eye protection.