Will this work for cleaning?

This is probably a dumb question, but will CLR work to clean the calcification(sp?) off the bottom of the boat? Is CLR going to damage the paint or fiberglass? Would diluting it to a milder mixture help? I mean you can use it on showers and tubs which are primarily fiberlglass as well. Any other easy suggestions to getting tough water stains off the hull are welcome.

Thanks