This is an inverse of the "Lost Overboard" story.
We used to live on a slow moving deep river.
One day, a guy in a beautiful strip planked wooden canoe went by motoring upriver.
He was powering his canoe with a 2 hp Evinrude
outboard motor which was attached to a piece of Cedar board.
This was in turn, attached to the side of the canoe with a C clamp.
He hit a boat wake, the board split in two, sending the running motor to the bottom.
Without so much as even a quick search, he paddled away.
The next day I went diving
. The river was about 7 to 10 feet deep.
I found the motor, replaced the head gasket
which was blown, and the virtually new motor ran for years until I sold it for $200 when we left to go cruising.