Way back in the day, I used to have a Jet Ski, and rode with a bunch of
other people who owned them as well. I had seend several Jet Ski's sunk
in the ocean. Only to be revived a half hour later on the beach. The
general method was a good freshwater rinse. Pull the plugs, spray CRC
heavily into the cylinders, turn the engine over several times, coat
the exterior and all electronics with WD40. Make sure the fuel is good.
put the plugs back in and start em up.
As a matter of fact, I even saw a Jeep Wrangler that was submerged, and
had the engine hydro locked. We took the plugs out, turned it over
until there was no more water in the cylinders, sprayed WD40 in the
cylinders, and on everything else. Put the plugs back in. Started it up
and drove it to the nearest convienent place to change the oil. All was
well.