Mostg efficient product&method for removing Green&black growth in the waterline?

[Karlsenkystfiske]

Have taken the mighty "Solringen" on land for maintenance after being left still for 3 months all summer. Overgrown with shells and other biological material I have some work to do in order to get her all clean.
The growth just above the waterline is very stuck. High pressure with turbo nozzle could not lift it. Rotating drill brush and soap/degreaser have removed some, but not all of it. Maybe if I scrub the same spot for a lonfg time... Surely there must be a better way?

 

[Refueler]

Cilit Bang Lime and Rust cleaner was brill for this until they changed the formula ... now its useless.

I now use Spray on Oven Cleaner .... type that foams up and stays working in place ... but needs to be well rinsed off.

Another of course is Oxalic Acid mixed strong and a bit of Wallpaper paste added to create a thin paste to cling where put.

For small areas - I have used Car Wheel Cleaner ....

 

[Baddox]

Soapy water and a brillo pad worked for me. The pad wasn't abrasive enough to damage the boat but still removed the weed residue. A quick polish afterwards brought the shine back.

 

[pandos]

Soapy water, ciff cream cleanser and a green scrubbing pad...

 

[Chiara’s slave]

Soapy water, ciff cream cleanser and a green scrubbing pad...

And a plastic ice scraper for car windows for the really tenacious stuff.

 

[William_H]

I get very similar stain which comes off immediately with oxalic acid in water. I use a spray bottle but keep your nose away or wear a mask. I actually spray the topsides near water line while it is in the water with me swimming alongside. It needs it after 8 weeks in water. By the time I get around the little boat it is clean except for bits missed so I go around again.
Now if oxalic does not move it then try acetone for grease/oil stains. If that fails try bleach. ol'will

 

[Karlsenkystfiske]

I get very similar stain which comes off immediately with oxalic acid in water. I use a spray bottle but keep your nose away or wear a mask. I actually spray the topsides near water line while it is in the water with me swimming alongside. It needs it after 8 weeks in water. By the time I get around the little boat it is clean except for bits missed so I go around again.
Now if oxalic does not move it then try acetone for grease/oil stains. If that fails try bleach. ol'will

I tried with HCl. "Salt acid" we call it. Did not work. Perhaps oxalic has different properties/reactions.

And a plastic ice scraper for car windows for the really tenacious stuff.

I have a bakelite scraper that is very tough

Soapy water, ciff cream cleanser and a green scrubbing pad...

Like a scotch brite pad?

 

[pandos]

I tried with HCl. "Salt acid" we call it. Did not work. Perhaps oxalic has different properties/reactions.



I have a bakelite scraper that is very tough



Like a scotch brite pad?

Yes ideally with a sponge on the other side...I find that the sponge holds moisture and keeps the whole operation well wetted.

 

[Daydream believer]

I find Ajax better than most solutions with fine grains. Then use scotch bright pad & elbow grease to apply if a sponge does not do the trick

 

[B27]

On the anti foul, I find a plastic scraper removes any masses of weed etc.
A scrub with a stiff brush or scotchbrite or similar scouring pad then cleans things up.
Finally a rub down with wet sanding paper or a wet sanding sponge removes the traces of weed and smooths the surface of the paint , so weed is less able to stick and the surface is easier to clean in future.

On the gelcoat, you don't want to use harsh abrasives, I use a soft brush, some detergent, maybe a plastic scraper, then cutting polish and wax. If the gelcoat is rough, maybe really fine wet'n'dry paper like 2000 grade before polishing. Or maybe one of the coarser grades of Farecla?