Re: Chesapeake boat ramps?
Bill has a good link for the Virginia DGIF website for a search. In my experiences, the public ramp in Newport News (by the James River Bridge) is a good one. It's located on the James River. As far as I remember, that one is free.
The other public ramp that may be good for your desires is one in Virginia Beach called the Lynnhaven Boat Ramp by the Lesner Bridge off Route 60 (Shore Drive). That one is pay, but I don't remember the rates. It does, however, pretty much put you at the mouth of the southern end of the Chesapeake Bay.
Baltimore seems like quite a distance to go waterway.