Stop in for a cup of coffee

Evening everyone!
Did a service call to check out a boat that stopped.
Guy was pulling his grandkids around on a tube. Stopped motor (4.3 gm) omc. So kids could climb into boat
Wouldnt crank back up.
Said it made strange noises when he stopped engine.
It was locked up. He thought battery was dead.
It was hydrolocked. All 6 cylinders had water in them.
Pulled plugs,dried it out and fired right up.
My educated diagnosis is engine hadn’t come down to an idle, when he shut it off it ran on.
Then it bucked and did a couple backwards revolutions and sucked water in through exhaust.
Not bad considering he figured he seized it.
Was a nice evening on the waterfront,sorted out a disaster (no charge)
Did my good deed for the year...