Hi guys,
Could someone please have a look at this pic and help me with what it may be and the best way to clean it?
I have tried scrubbing with water but and reluctant to use anything that may "set" the stain.
Can I use CLR on it perhaps? Will this hurt the boat?
Cheers,
Matt
Could someone please have a look at this pic and help me with what it may be and the best way to clean it?

I have tried scrubbing with water but and reluctant to use anything that may "set" the stain.
Can I use CLR on it perhaps? Will this hurt the boat?
Cheers,
Matt