What you need to think about is living on board for extended periods of time and how many people will join you. Obviously you have to have enough sleeping accommodations and maybe more than one head will be a good idea. You have to have an inboard engine that is adequate for the task. Some manufactures will offer a basic engine to keep the price of the boat down, but then have an upgrade to a larger inboard which is really what you probably need. Next you need to have enough fuel capacity to motor long distances if there is no wind, so a larger fuel tank is advised. Next you have to think about water capacity for cooking, drinking and showering, etc. Then you have to think about galley accommodations - cooking facilities with enough propane, etc to take care of your needs for longer periods of time. You want to have a big enough ice box or refrigeration/freezer to hold food for longer periods of time. The boat itself should have adequate storage so that your living area of the boat is not loaded with gear. As far as navigation you want to have the bare essentials and maybe more to include depth sounder, knot meter/log, VHF radio, GPS/chart plotter, compass and radar is nice, but not essential. Back up hand held GPS and VHF is also a good thing. An EPIRB might be another thing if you are doing a lot of offshore sailing. As far as the boat is concerned, you want to buy a boat with an A classification for offshore use. That way you know the boat is built to specifications to withstand severe ocean conditions. That means stanchions and lifelines are more heavy duty, hull to deck joints are built stronger, windows and ports will withstand more, cockpits have large enough scuppers to ship out unwanted water, the companionway has higher bridge decks so water won't enter the cabin easily, companionway drop boards will withstand more abuse.....on and on. Rigs and sails designed for such use, etc. Windlasses are nice as you will probably want more chain and need to save your back. These are the things you need to think of, I think, in addition to cockpit cushions, dinghies, foul weather gear, mosquito screens, etc.
