The Dismal Swamp Canal is tight for a pass with two 14' beam boats. With 28' you will have to stop, pull over to the bank (while dodging overhead branches) and then the opposing boat can slowly pass. It will be tough but probably doable particularly with your 3 1/2' board up draft). The canal is pretty and the Visitors Center is a nice place to stop for a day and socialize with the other cruisers (but not rafted!!) and Elizabeth City is one of the friendliest cruiser towns on the east coast.

David