Weve done the Delaware many times on our way to New England in the summer. We usually go from the Patapsco to Reedy Island 5 mi south of the canal on the Delaware side. Then we weither get up real early or wait until; the express (tide) runs down to Cape May. Usually is a shorter day when you do it from Reedy to beigin with (42 miles) if you catch the current you go 8 knots for 4-5 hours. Comming back we usually can make it to at least the Bohemia...usually the Sassafras. Again you have to play the tides.
As was said the lower bay when the predominant SE wind runs against the tide...it gets ugly. Short...choppy....square waves. Thunderstorms can stop you dead if running against the tide and chop. We make the Delaware enjoyable by taking short turns at the helm...11/2 hrs and playing rock and roll. Best advice for Green heads is avon skin so soft and flyswatters. One year my wife and I counted 123 of them dead in the cockpit. Those who have never experienced a green head ( I lived in ocean city NJ for 20 years), the only good greenhead is a dead greenhead. They bite till they die.