If I understanding you correctly you need something to remove bird poop? A little story first: We keep our boat in Three Mile Harbor which is in East Hampton New York. A beauiful place except on one weekend in July when everyone shows up for the fireworks and for a couple of weeks in late august/early sept when we are visited by a few hundred (thousand? well alot anyway) piping plovers. They little bastards will make a mess of your decks, sailcovers,
dinghy, etc in no time. Made the mistake of not going out to the boat one weekend and it was COVERED in guano. Dried on like tree sap. I was unable to find anything to remove the stains so I ordered a product called "poop off" I think the website if poopoff.com (NO, I have no economic interest in the company) I found it to work better than any other cleaner. I used it on the decks, the
lines, stainless steel pulpits and on the mainsail cover. Given the severity of my problem, i sprayed it on and then covered over the spots with a wet paper towel. Let it sit for 15 mins or so and the stains came right out. As for keeping birds off the boat to begin with, I have tried everything. What hasnt worked for me: fake owls, strings of pennant flags, "scary eye" balloons. What has worked: monofilament
line strung across the top of the mailsail cover wud also work on spreaders and i bot a kit that suspends the
line an inch or so above pulpits (Ill find the name of it for you), plastic bags (the small white ones you get at the 7 Eleven) tied to everything you can, and a product called the jumpo birdtrainer. Good luck.