Frank,

Not sure if you Dory is considered a car-top boat or not, but here is a link to "cartop" boat launch sites in Anne Arundel county

http://www.aacounty.org/RecParks/launch/

Also, Truxton Park in Annapolis has boat ramp with a small fee and offers a protected area.  Sandy Point State park has nice boat ramps, but aside from the cove where the ramps are located, it puts you right on the bay.  Although AA County has lots of shoreline they have relatively few public launching areas.

You may want to try the Launch Site App from Paddling.net.  It shows quite a few site in the Chesapeake and you can add to that.   

   Try this link for MD launch sites.  Prices and regs vary.

http://dnr2.maryland.gov/Boating/Pages/water-access/boatramps.aspx

There's also private ones, again with varying access.  Try here:

http://www.thebayguide.com/old_site/launch.html

The Bay Guide site has several possibilities on Magothy River, which can be a nice small boat venue, esp. during weekdays when there's fewer high speed motorboats.  If you have a hand dolly for your Dory, you should be able to use many of the canoe launch sites, since they are typically beach/shore launch sites.