on the boat, i'd recommend a fixed mount or one with a swivel arm that can be locked down while underway. I've seen these before on the net and the prices are decent. In store stuff will be pretty darn $$$.
I saw a LCD TV on a 28' Pursuit WA i was looking at last summer, it had a swing/swivel mount which allowed it be used inside the cuddy and to swing out and be seen facing aft into the cockpit while the door is open.