INVESTIGATOR 563

I have the usual scum line on the hull that comes from lapping water above the anti fouling. It always gets ugly prior to haulout.

I tried as an experiment hitting it with some clr while I was fiddling with bilge pump inside the boat fixing a disconnected handle. It was about half an hour later I came out and the hull was not only clean but white. Certainly worked better than boat acid. Which usually takes a few applications and a scrub. Anyway I will experiment further and report.

Hi Ozzie. Also try phosphoric acid, which is rust converter. Works a treat. Also brilliant at removing that light rust looking stain on stainless steel railings and fittings as well as the brown stain on the hull above the waterline.
Cheers

When using any of the acid based cleaners you must pile on the polish to protect the gelcoat. With our boats' age the wax surface has long gone from the gelcoat which makes the surface porous - which is why it gets dirty easier - so the pin holes need to be "filled". Penetrol is very good to achieve the protection. Careful using it and stick to the directions

I use Johnson Floor wax as a final coating on the hull sides. After using normal marine polishes and cleaners it gets Johnson’s floor wax.
Every time!
You can walk on it .