As for your question, no. You can't take a ship out of to sea. The only time you can do that is when (Spoilers, please highlight) you get the quest to go to the Lost Bay (If you have the TLC version, that is).
__________________ "I have seen the blood and dirt on their faces. I’ve seen young boys turned into soldiers. I’ve seen men ripped apart by bullets. I can’t forget these things I have seen. And so I ask myself: How much more can one man take?" -Sgt. Matt Baker
Most of the ships in the game are for pure astethics only. Even the ship which Des stated is taken in a cutscene.
__________________ Police arrested two teens today. One was drinking battery acid, and the other eating fireworks. They charged one and let the other off.