If you find yourself getting a little bit bored photographically and you're looking for something new and different to photograph, take a drive to the nearest harbor. I happen to live near Long Island Sound so there are lots of nearby harbors and I find them extremely interesting. The small harbors, like the one on the Housatonic River near my house, has a lot of local fisherman, small sailboats and a thriving oyster industry. It's a relatively quiet harbor, but there is almost always something interesting to shoot and I should probably pay the river a royalty considering all the photos that I've shot there and had published.
When I'm feeling really restless though, I head up the road to New Haven harbor. New Haven is a fairly busy city harbor and has a lot of huge freighter traffic. The freighters are surprisingly easy to get a shot of too: either as they transit in and out of the harbor or tied up to a mooring as they offload their cargo. It helps if you have a long lens when you're shooting ships because often the best views are from the opposite side of the harbor or from the shore as they pass by. If you can get out onto a breakwater you can often get very close shots with a much wider lens. I've shot from docks at a few industrial harbors and had captains wave at me as they cruise by--exciting stuff!
Incidentally, keep an eye on tidal charts if you want to get ships coming and going because, obviously, this is something they only do at high tide. You might also contact the harbormaster's office and ask them if there is a shipping schedule available. And always keep an eye out for tugs on the move since most harbors require a harbor pilot to go aboard and control the ship as it enters or leaves a commercial harbor. Odds are if you see a tug heading in or out (a good shot all by itself) there is a freighter about to arrive or depart.