Liveaboard Washington DC
I liveaboard and commute from Galesville (about 12 miles south of Annapolis) to Vienna (about 10 miles east of Reston). I used to live in Reston and commuted to the boat on weekends before living aboard.
An hour commute from Annapolis to Reston would be your approximate time on a Federal Holiday, during the summer, when the President, Congress, and the Unites States military were all out of town and the sun was shining (not to brightly) and most of the DC metro area had the flu.
Other than that, you can easily figure at least 1.5 hours each way (leaving at 0530 and 1500, respectively). If ANYTHING, and I mean ANYTHING, unusual happens, you can easily DOUBLE or TRIPLE your commute.
The Wilson Bridge (the I-95 corridor crossing of the Potomac) is in the process of being replaced. The traffic there will be a nightmare for the next few years and the overflow will choke every artery in/around DC.
Did I mention the day a fellow stood on the Wilson bridge and threatened to shoot himself? 6 hours later, they reopened the bridge. A friend commuted home, through the District (not over the Wilson Bridge) that day. Only took EIGHT(8) hours...ONE WAY.
It can be done, though. Look at Herrington Harbor (Deale, MD). Not sure about liveaboards. Also in Deale, Shipwright Harbor. A bit further north is Galesville. Check out Harge''s Yacht Yard. You might also check marinas on the Rhode River, South River and Magothy Rivers.
A friend of mine lived aboard in Baltimore''s Inner Harbor for a year and took the MARC (trains) to the Metro in DC.