stains on hull - oxalic not working

[johnkeith]

Just back from giving the hull a good washdown with oxalic acid - did wonders for the waterline yellowing but hardly touched the grey deposit that built up over the summer. The boat is kept in the Gareloch in Scotland and one local told me that the marks are due to the high level of navy activity belting out diesel fumes. Whatever the cause these stains seem hard to move - any ideas?

 

[pvb]

I've found that own-brand "creme cleaner" (aka Cif) used very gently on a sudsy sponge will shift most stuff.

 

[VicS]

As PVB says.

If it is an oily deposit you will need a detergent based cleaner like Cif rather than an acid based one.

 

[matelot]

Oxalic acid isnt a magic bullet thats the answer to any dirt problem. Try something else. I used to find my wife's liquid detergent (the stuff for the washing machine) very good.

 

[oldsaltoz]

Try a small area with a degreaser.

 

[MoodySabre]

I'm a fan of Magic Eraser . You can get it a Robert Dyas, Lakeland, some supermarkets do own brand of this. Remove scuffs and dirt, non abrasive and detergent free. There's a boatie brand but it's all the same stuff. Also brilliant on UPVC.

 

[starboard]

Oxalic will only work if the hull temp is well above 10c....wait a week or so and try again when the temp gate around 15c or more!!