Is this your boat? SPARTAN 25 (BUCHANAN)
My home port is at Indian River, DE and have also contemplated the circumnavigation in my Helms 25. From what I've read, you can go through the bays and channels inside to Cape Charles. You would have to research using local knowledge for water depth and some bridge heights. If you Google "Delmarva Circumnavigation" you can see some good reading. Here is an example http://cblights.com/cruising/Delmarv...navigation.pdf
I have done the circumnavigation of Rehoboth Bay, Lewes/Rehoboth Bay Canal, Delaware Bay, Atlantic Ocean, Indian River Inlet, Indian River Bay loop. Its a full dawn to dusk trip in the spring for the longest daylight.
Feel free to PM me after you read some of the articles and books on the Delmarva Circumnavigation. I have a swing keel and would be very interested in taking the Chincoteague Bay route from Ocean City to Cape Charles.