Brown stain along waterline

[Dazedkipper]

My boat has a brown staining to the gelcoat along the waterline - any suggestions how to clean/remove it?
I have tried Y10, 3M compound, Viakal, Oxalic acid.

 

[FWB]

So no antifouling nor boot top?? Why not either raise the antifouling to well above the waterline, or paint a Boot top with Trilux?

 

[aledlgriffith]

I use Y10 to remove the brown staining, have you left it long enough, the instructions state 10 minutes, I have had to leave it a little longer in the past, depends on temperature etc.

 

[westernman]

Use the holding tank!

 

[starboard]

Y10 will do the job but leave it on long enough and only do it on a warm day....it only works above a certain temperature

 

[benlui]

Y10 again i say!
However, i have similar staining, which is almost of a gritty feel too. I use shampoo,then Y10, then i seal it with wax.
But as others say, leave it soak for a while. I did my boat last week and left the Y10 dry on in the sun for 20min which brought it up in an amazing white colour it turned out like new.

 

[William_H]

I would say that Oxalic acid or one of those rust converter type acid preparations would fix it. You apply and allow 10 minutes for it to work.
I have found lemon juice will also move the stain. olewill

 

[oldsaltoz]

'Some' waterline stains contain oil, applying an acid based product can be a waste if the surface oil has not been removed.

Washing the area with a degreaser of washing up liquid will help any subsequent treatment.

Avagoodweekend......

 

[pappaecho]

In Pompey hardbour we seem to get diesel residue with is electostatically attracted to the white gelcoat above the waterline.
We remove it wilh Cillit Bang