T&T: Canvas Cleaning

[Ron Nelson]

We just got back to the PNW after 4 months of snowbirding and found the boat
covered with dirt and the famous NW green stuff.  This comes off the
fiberglass OK but the green stuff on the canvas dinghy cover is more
difficult.  I tried scrubbing with a stiff brush and most of the green stuff
comes off but I am worried that I could be damaging the canvas as it takes a
long time of hard scrubbing to have any effect.

Does anyone have any advice on getting this green stuff off without scrubbing
the life out of the canvas?

Thanks
Ron Nelson
DeFever 45 PH
Port Orchard, WA