[rhinoz]

Ok, this is going to open up a can of worms on what works best for hull cleaning a fiberglass boat.

I have a "watermark" from bow to stern, just looks very faded and I think it might be algae, not sure BUT I've been reading like crazy on different hull cleaners.

There's Zing , On/Off, Starbrite buffered acid, "The Works" toilet bowl cleaner (I had to chuckle at that as I guess crap is crap LOL ), diluted white vinegar and a whack-load of others.

I'm looking for some advice as what to use to remove the water mark and what to use after the water mark is gone, all help appreciated on this.

Thanks

[SinfulDragon]

I've been reading a bit on this myself, my favorite so far is the Magic Eraser. I'm really wanting to give that a try on the hull as well as the seats. That little thing seems to clean everything else under the sun so I'm pretty hopeful here.

[rhinoz]

I tried magic eraser, didn't do a thing...worked on everything else though...

[Dozer]

Probably have to buff it off with a polishing compound and then a couple coats of wax.

[Motoxxx43]

Muriatic acid. 6$ a gallon. Works like Zing but 1/5th the price. Cleans the out drive well too.

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[rajjneef]

On/Off works well. You have to be careful using it though.

[ShabahZ280]

I have always had good luck with the Bass Pro Shop's Heavy Duty Hull Cleaner. It is an oxalic acid based cleaner, so wear gloves, but i'll tell ya, it works like a champ!

For some really heavy stains, my sailboat friends use something called FSR (fiberglass stain remover). They say it works good, but I've never tried it.

[schevel]

On/Off has worked well for me as well, I have the same watermark problems as you.

[nglauer]

I picked up some Captain Mike's boat cleaner a few months ago at a local RV shop to use on our camper (It was covered in the nastiest pine sap and have LOTS of black streaks from where I stayed in it all winter for work). How the RV shop was turned to this stuff.. I have no idea (as it is not marketed for RV's) But they kept BUNCHES of it in stock because it has become very popular with their RV owners. It literally eats the black streaks, sap, and road grime off a camper. I also tried it on my hull (I had a few lingering stains that were left on the boat over the winter) and is cleaned it off like nothing (however AVOID decals). I highly recommend this stuff.. and you don't have to fear getting it on your trailer either.

http://www.tatesoaps.com/brochures/3...%20cleaner.pdf

Perhaps someone else has used it and can chime in (I used it extensively on our camper... which it only took 3/4 of a 32oz bottle to detail our trailer - 27ft - top to bottom before the new owner picked it up). I will know more about how well it works on the boat in the next few weeks (I plan on testing it on our Arctic White interior and inside the bilge area)

[nglauer]

Here is a place that sells it as well as some of their other cleaning products: Captain Mikes Boat Cleaner - 1 gallon [320-01] - $13.00 : A Better Way to buy KORKAY(tm)