Tired of hotel hallways, ice machines, and coffee shops? A small flotilla of sailboats and cabin cruisers moored at Jack London Square are rentable by the night. (These include the 32-foot "Sand Castle" and the custom-built 65-foot "Capriccio," at a cost of between $125 and $400 per couple per night.) You arrive in midafternoon to be escorted to "your" yacht by a member of the Dockside crew; a quick guided tour shows you how the lights work, where to watch out for low ceilings, and assorted ways to acquire sea legs. Then you're on your own to explore the boat, hang out on deck, contemplate seagulls, and decide where to eat onshore. After dark, gaze out at the far-off lights of Alameda, watch a crane loading containers onto a Shanghai-bound freighter, and tell a few fish tales. Then it's off to the bunks to be lulled by gentle waves and the sound of water slapping the hull. In the morning, fruit and pastries await in the galley cupboard. Ahoy!