Before you rip the head off look elswhere and see what can be eliminated.

Water can get into the oil via oil coolers and engine mounted water pumps.

Try removing the injectors and spinning the engine. Do any water droplets come out, this may give a clue.

Is there a ventted loop fitted as with the long layup the vent valve may have salted up and allowed water to syphon into the engine when you stopped after the first run.

Hope you find the answer soon so you can go sailing.