I learned to sail in college in the late 70's taking PE classes at the yacht harbor in the university's 12ft dinghies and 30ft full keeled sloops. A couple other guys and I were had our turn in one of the sloops one blustery winter afternoon. The dinghies made their way out of the slips and out toward the bay while we slowly got backed out of the slip and headed down the channel. By the time we got to the harbor mouth the wind was really howling and not one of the dinghies was upright except that of the instructor. We were observing the mayhem of upturned boats and panicked sailors when the relatively large surf slammed our keel down into the sand bar that had developed near the end of the breakwater. We tried to sail off the bar, but each successive swell drove us into shallower and shallower water. We were slamming down on the bar with each swell, heeling almost 45 degrees, and holding on for dear life when the instructor started screaming at us to get that boat out of there. We politely screamed back, how in the hell are we going to do that? He said to get out, get under the boat, and push each time a swell lifted the boat. So we loosed the sheets, dropped the sail, climbed out into the surf, and somehow managed to wrestle the boat back out to the channel without drowning or getting crushed between the bar and the keel. We then dragged our wet, sorry asses back aboard and snuck with our tails between our legs back to our slip. We didn't feel bad for long, though, because we got to watch all the even worse-for-wear dinghy sailors coming back one by one. Two of them had been dismasted and came back under paddle. As an understatement, the instructor admitted to us after all the boats and people were accounted for and secured, maybe he shouldn't have taken us out that day.