Yellowed hull

[Wizard]

As your fiberglass boat ages, it may get a condition called Yellowed hull. Your normally white hull has discolored from the sun, water pollutants, etc., into a hull partly to totally yellowed. Dealers can clean your hull with Muriatic acid, a hazard chemical, with much scrubbing and power washing. I have found and used a product called Nu-Hull on an older bass boat and my wife's cruised. Easy to use: spay an area thoroughly, let is sit for five minutes and wash off with a hose. A large bottle, good for 5 bass boats, costs $40 versus $150 to clean at the dealer.
Disclaimer: wash small areas at a time as the cleaner shouldn't dry on the hull. For problem areas I used a cheap deck brush and cleaner to go over the hull again. You will need to rewax your hull.

Wizard

[Mike Cork]

Great Tip

[Sixpack]

When mine gets that dingy, yellow color I put a little soft scrub on my wash brush and wash it away. Works great....