Stopping gulls at the dock is hard . Eliminate any food if you can and that often means fish parts from cleaning fish. If you do need to dump fish scraps, get a 5 gal bucket and cut out the bottom. Then float the pail ( now a cylinder) in the water with some line to tie it off. Dump the fish guts into the bucket. Gulls won't go in the bucket and the guts will float. Crabs and other fish will eat the meat.
Those plastic birds they sell that are supposed to keep birds away will work for about 30 minutes. The gulls aren't stupid. There are whirly gigs that work on boat tops but to be effective they have to be jsut about as wide as the top. These things spin in the breeze and sort of sweep the area. Birds don't like them.
I've come across this issue as well when mooring past boats on a mooring buoy in front of our beach cabin. The neighbor has a GW and uses canvas covers, an owl and the things that twirl around... none of which work too terribly well. I think I still have a picture somewhere on my phone when I was rowing my boat back in and saw a seagull sitting next to the owl on his boat near the outboard. As stated above, they're very smart and with something that doesn't move they know it's not a threat. I've seen at ferry terminals things that look like porcupine quills on small piece of metal that extend out so that the birds can't sit on top of them. They work pretty well on the pilings and so forth. That being said, I'm not sure you'd want them on a dock.
I have found that hanging old cd's from a line around and on my boat works great at keeping the birds at bay. Birds hate the flashes they make and do not stick around. I learned this trick off of THT forum. I have tried owls and other tricks without much success.
Bayson, it would help to have a picture of your dock since there many variations. Depending on it's setup will determine what may/may not work. For example, a string tied about 8" off the railing will prevent them from landing there.
Folks have tried many things. Some that I've seen that work:
- Spike sets that go on top of fixed items like poles.
- Small colored flags and CDs tied together to over the bow, cockpit and hardtop.
- Plastic birds that move, although I agree the effectiveness is short lived.
- Gullsweep or spider wires on top of hardtop.
- Tight scope lightweight netting.
It is like burglars - make your boat a bit more difficult than your neighbors.