My slip, 2 in from the outer tee, is 19ft water depth at low tide. Closer to the shore it shoals to 5ft, and the travel lift shoals to about 3ft at low tide.
The outer tees at Anchorage Marina, 3 marinas up river from me (1 block by land), are all in the low 20's at low tide, with shoaling close to shore about 3ft.
Water depth in the channel behind Little Tinicum is in the low 20's shoaling to the low teens at the up river airport end and the down river Darby Creek end.
So if you can tolerate the aircraft noise you will never be constricted by draft.
1970 Havsfidra 20 by Fisksatra
On the Delaware River at Fox Grove Marina Essington PA