I had the hook down in a popular anchorage this past summer, when a seagull kept landing on our dinghy as we were trying to eat. No doubt, they've been fed and "learned" its good to stick nearby. If not fed, they've also been known to swoop in to steal food right off the BBQ, if you step away for a second.
So I begin thinking I would like this one to learn that sitting nearby might not be a good idea. I don't want to hurt them (well, I do, but its illegal), so I fashion a makeshift slingshot with a rubber band and use broken pieces of paper clips to to wrap around and shoot at the flying rodent. Certainly not going to hurt it, but may suggest somewhere else is more pleasant. Somewhere like your boat, if you object to my callousness.
I landed a couple of body shots from 6 ft and, sure enough, the rodent decides to stay away.
So I think having a real slingshot aboard may be a good idea. I search around and there are both soft and bio-degradable projectiles. I'm not thinking I need stainless steal hunting ammo, just bird behavior modifiers. I don't want to accidentally hurt anyone else either, or my boat for that matter. Cheap solution, but when I click order, it tells me they can't ship to Rhode Island.
Holy smokes, after a quick search, its turns out that sling shots are actually illegal in RI !! Mass too !! I couldn't believe.
Not wanting this to become a gun/slingshot control thread, I would like to focus on how you keep these crap producing flying squawking rodents off your boat. I'm not referring to the standard spikes and wires that are used to keep them off spreaders, but how you keep them from landing 6 ft away, with you aboard, and waiting for you to slip up with your food.