Auto/boat engine mechanics?
 

The oil pressure gage on my boat....V 6 engine.....pegged at the high end of 80. Normal running is 40-ish.

Plenty of oil, engine is running normal.

I assume it is either a bad gage or a bad sending unit in the engine.

Are there any other possibilities?

Btk

oil filter clogged?

Cylinder compression leaking into crankcase ?

oil gauge
 

short in oil gage wire remove from sending unit and check gage,to see if it goes to o .

Mine went to max with open circuit at sending unit. Check for disconnected wire.

I would Do a direct pressure check. Remove you sending unit, hook up direct pressure gauge. Now you will know what the true oil pressure is... based on that You either got good oil pressure or malfunction gauge/wiring... If you have bad oil pressure for instants high in your case it could be clogged oil system (filter or internal passage), relief valve malfunction... Most likely as suggested in sending unit or wiring problem. usually when the system clogged it blows the oil filter off from too much pressure (very rare occurrence) . simple direct pressure reading with tell the truth.