Last Saturday, while tied up at the restaurant on the south side of Knapps Narrows, adjacent to the bridge, we looked up and saw a sailboat drifting stern first toward the bridge (which was closed at the time). Their engine had apparently stalled, and they were about 100 feet away from the bridge in current that was running about 2-3 knots. There was a couple in the cockpit, and another couple on deck. The guy on deck had grabbed a small Danforth type anchor and rode, and tried several times to heave it and then immediately snatched the rode in hopes it would snag. (It didn't.) The boat then collided broadside with the bulkhead close to the bridge, and the woman on deck grabbed the bulkhead and yelled for others on board to do the same in hopes of preventing the boat from colliding with the bridge. She got no help and was not able to hold on. The boat then drifted stern first into the still closed bridge, and the back stay acted like a spring and bounced the boat back off the bridge. At that point, the engine started and the boat was moved away from the bridge with no apparent harm done. This all happened within about 30 seconds to a minute. One might ask why the bridge tender did not open the span - however, their observation post is on the Choptank River side of the span, and this event occurred on the Bay side, close enough to the span where it was not visible to the tender.I offer this as a couple of thought provoking questions: What would you have done in this situation if you were the captain of that boat (looked to be a sloop of about 30 - 32 ft)? What would or could you have done, if anything, if you had been on a boat close by observing this action?Ed Ryan