In the interim, a spattering pattern of orange rust stains appeared on the bow of the deck - possibly caused by the anchor and/or chain - but also possibly caused by insect & spider droppings (apparently) - and I discovered some kind of a nest under the bow roller platform.
Using a stiff brush, II tried scrubbing with:
- Soap & Water (result: no improvement)
- Vinegar (result: no improvement)
- Oxi Clean (result: some improvement)
- Star Brite Spider and Bird Stain Remover - (result: Much Improved)
Another product that I may try in the future:
I would be very interested in hearing what others have found to work - please post your comments below.