Many years ago (in the 1950's), my in-laws (with my wife as a five year old) were on a hire-boat (Water Vole out of Gas Street Basin - a converted working boat)and on entering a lock, the mother-in-law who was steering, held back too close to the bottom gates and the blade of the rudder was trapped between them as they were closed.
The bow went up in the air as the lock filled and the water lapped over the stern. They only just sorted it out in time!
Just read this out to the wife and she says it goes no-where close to describing the pandimonium that occurred as her father, opening the paddles, couldn't hear her mother shouting over the sound of the rushing water.
"Rodney, Rodney, get the children off the boat, we're sinking!"