Good question...
I tried Island Girl products on mine twice. The initial results were great but after 3-4 weeks they started to turn brownish again. Island Girl works great on lifelines though. The side of the boat that normally faces the sun is the worst, parts in the shade don't seem to be affected. In desperation I pulled out the big guns and tried acetone which also worked for a few weeks but is pretty nasty stuff. It does seem to be sun related though, maybe I need to rub sunscreen on the rub rails every morning? naahhh...Hopefully someone out there has a good tip!