If this is fiberglass, I would try EZ On/EZ Off. I think it is a starbright product. I keep my boat is a river all summer and it grows some hair in the process. This stuff cuts right through it.. Brush on Brush off..
I use a product called "Simple Green". They sell in a diluted spray bottle or you can buy it in a gallon industrial strenth.Use it straight up. works wonders cleaning just about anything and its not a heavy chemical. Can wash cars as well as household cleaning. Just have to spray it on and let sit a few min.
wal mart sells crown spray cleaner for about 2.00 and this stuff works great on every thing be careful there are some cleaners out that will hurt your vinyl like simple green
The cheapest way to clean the scumline is to get the cheapest toilet bown cleaner at Walmart and spray or wipe it on,wear gloves.About $1.I keep a jar of "fiberglass stain cleaner" in my boat which is less caustic and is a gel so it will stay on for the 30 seconds it takes to work.It comes in a plastic jar and is a blue gel.Got it at West marine for less than 10 bucks.It is important to put a few coats of wax on the water line or the scum line will come right back in a few days.Charlie
I agree with Charlie. I got some sno-bowl and it ate that crap right off. Be careful around metal, especially aluminum as it will react with it and eat it up. Spray the stuff on, wait a few minutes and spray off with water and then towel off. This stuff will remove the wax too so you may want to re-wax the areas you use it on.
Soaps and detergents will not touch most hull "scum" stains.<br /><br />There are several brands of "hull cleaner" available at marine centers. They consist of an acid (oxalic or others) which is safe for use on fiberglass and gelcoat. You can get "Dekswood" deck cleaner at the hole center, dillute it about six to one with water, and it will do the same thing (it's the same chemical) at a much lower cost. Read the directions and protect your skin and eyes.
Most toilet bowl cleaners contain hydrochloric acid (otherwise know as muriatic acid in hardware stores)in a thickener. The least expensive way to clean the hull is to purchase a gallon of muriatic acid at Home Depot (probably in the swimming pool chemical section) and use it on fiberglass only, avoiding metal and fabric. Use gloves and eye protection. It will not harm cured fiberglass, but it will damage other things including you .