Waterline removal on hull suggestions?

On and off hull cleaner. Put it on the line with a paintbrush, let it sit for recommended time and hose off. Use plenty of water and keep the trailer covered or wet

A cheap readily available acid based cleaner is The Works toilet bowl cleaner, 20% Hydrochloric acid. Usually $1-2 for 32 ounces vs. $12-15 for Star Brite, which is 5-10% oxalic acid.   It can be diluted still further with water. Protect anything painted or metal, don't use it sitting on concrete. It seems to work better on a damp hull. I like the idea of "painting" it on to avoid getting it somewhere you don't want it. Wear long (kitchen type) gloves and avoid getting inside the gloves. A magic eraser cleaning pad will help with the tougher spots.   

Toilet bowel cleaner straight will take the wax off if your not careful. It takes off the stains though!! Ask me how I know.

Collonite Hull Cleaner seemed to work really well. I only used it on spots I missed or didn't come out using the Starbrite Hull cleaner. The Collonite seems like it would be an expensive/labor intensive way to do the whole bottom.
http://www.jamestowndistributors.com/userportal/show_product.do?pid=7837

The stains might come back more quickly after using the acidic cleaner because it not only removes the iron stain but also takes whatever dirt and old wax is in the normal pores in the gelcoat. If you re-wax after de-staining, it will help avoid that.

Interesting, I wondered why it always came back in the exact same pattern.

Just make sure you do not get it on your trailer, skin, shoes, carpet, concrete, or anything else you do not want dis-colored!! I was also surprised how fast it destroyed a sponge. Gloves and goggles mandatory!! I have not found anything better for removing the tannin (rust) stains. As stated above it will "etch" the gelcoat so make sure you wax well before putting back in water.

harddock wrote: FSR    Fiberglass Stain Remover available @ West marine, Boaters World, and other marine outlets. Apply (smear on) wait 10 mins (go get a coffee) Wash off, and when dry polish(wax)the waterline. Simple and effective art getting the stain off.

I've been using FSR for a lot of years, I agree works well. It has oxalic acid which is the ingredient in a lot of the name brand hull cleaners. I like the way the gel goes on easily with a sponge and doesn't drip too much.

Here's a link to a MSDS on FSR:

FSR MSDS

Another "thumbs up" for the FSR product ... easy to control, works well. We leave our '94 SN in the water during our annual family vacation (otherwise it is always in and out) on a lake that seems to stain the bottom the moment the boat hits the water. Last year, I used Slimy Grimy (it also works well, but is difficult to control ... it requires a spray application), but tried the FSR this season and don't think that I will go back! DO follow with wax ... for what it is worth, I am a Collinite fan!