From experience, have a client that offers towing services for surfers, takes them to the point back again to catch a new wave. Driver sometimes flips entire rib/engine and says nothing to owner.
Although engine is rinsed with fresh water near inmediately after and engine springs back again to life, in the short run engine ends being seized because that's salt water and has lots of sand in suspension that gets to cranckase interior and mixes with all rotating parts which are oiled.
What you should do inmediately after is wash all engine parts with fresh water, tear appart cranckase and wash all rotaing parts immaculate clean to be on the safe side, re assemble back power head, change plugs and that's it. Now imagine all the sand that could enter engine just by lying on a sand bed for 1 hour....