MacGregorSailors.com

Has anyone come across rust discolouration on the coach roof or cockpit floor, I have a 2000 Mac 26X, I have tried to polish them out to no avail

Sounds like a job for Borax

Try CLR. I also use white wall tire cleaner on the black spots.

Bob

Borax, you will need to elaborate ?

CLR, again I must be slow this week

What about TSP?

Rust stains probably need to be removed with a iron/rust removal product - suggest using IronOut. This is a weak acid, uses include cleaning the resin bed in my house water softener - leads me to believe that if careful and wax afterward, should be OK with fiberglass.

Leaves and such that might spend some time on your boat may leave some brown staining--our oak trees leave a dark and difficult to remove stain due to tannin. We use Chlorox Clean up--which is a cleaner that has bleach in it. It works really well. Make sure the boat is in the shade on a cool day or morning... spray on and let sit for a while before washing with high pressure. I use a gas powered water blaster. (Keep chlorine products away from electrical connections and electronics.)
SILK

mastreb wrote:Sounds like a job for Borax

I bought some 20 Mule team Borax last night based on your testimony!