We contacted our boat builder and they gave us this mixture.
We have tried it and it seems to work on some.
The key is to let it dry completely after soaking it.
Powerwash as much of it off as you can
Mix this up and let it soak
1/4 CUP PEROXIDE
1 TBS. AMMONIA
3/4 CUP WATER
Powerwash off well.
Then dry completely! Before putting it
back in the water where it will not dry again for awhile.
Hope this works!!!!!