I went thru Knapps Narrows from Bay side on Apr 19 last at low tide. My boat draws 4 ft and I did not touch bottom but my depth sounder went blank a couple of times which usually indicates muddy water.
You really need to stay close to the nav. marker #4 when you enter from the Bay side. Once around #4, head a little to the right toward the marina entrance.
From the Choptank River side, you need to stay close into the channel from nav. #5 to nav. #6. Move wide and you may touch.