We're trying something new that is working. We have an old motor boat mooring minder right next door to us on the swing moorings. It has a nice flat top cabin that is a perfect home for the cormorants and Pacific gulls. It took them a year to find our boat, but they have started to hang out on the Bimini frame and pulpit. We put a row of those boat pegs on the spots that birds like to land and it puts them off. It's doing the trick, no poo over the past month or so.
Sorry couldn't rotate the image... (is that possible in this forum?)