Using Nobeltec's route planner, at 5.5 knots constant vessel speed through the water (not SOG), the difference in Annapolis to the Harbor of Refuge is only an hour (it's about 20 - 21 hours) non-stop. That's regardless of when you leave.

If you break the trip and pick the worst and the worst times to leave, it might be a bit more. It's basically about 110 nm, or so.

There are greater % differences if your speed were different -- but this is an example.

There are trip planner software that is integrated in with "tides and current" information. It's not perfect, but it's very helpful in trip planning where current and tides are an isssue. If you had huge rains, in Penssylvania (for example), you'd have greater current effects; but, because you're fighting these going up the Chesapeake, and then getting a boost down the Delaware, then you'd be in about the same place.

The beginning of August, is not too convenient for a helpful departure from the upper Chesapeake to Cape May during the day.

Now and hour more of blood thirsty biting flies in the Delaware Bay is not exactly the most fun to endure ;^)))))