67 sea ray / 78 chevy 305 electrical fire issue !!!!!!!

hello guys , its been a long time for me here , after learning a wealth of information from you folks I have been able to keep my hoopty pile afloat until now...no way to shorten this , so here ya go....my son and I are a few miles out to sea fishing , while in the ocean I don't shut off the engine ...we spent about 4 hours fishing just drifting with the engine in neutral at idle...every 20 min or so I put her in gear to return to the start of our drift and go back to neutral at idle....im fishing at the stern and look to the cabin and see smoke billowing out from the dash..a lot of smoke...uhoh.I run to see wth and at the wiring panel underneath is a ground wire red hot , grab needlenose pliers and yank it off the terminal .the boat stays running ad we head in with out temp , tach , oil press , or fuel gauges .not knowing what caused this , I replaced the burnt wires which went from the voltage gauge to the tach to the fuel gauge to the terminal .I couldn't find any problem other than being burned .I put the garden hose on and started it...gauges fine , running fine..hmmmm....then we launched the boat and went for a ride...shortly after launching...they burned up again....I have looked but don't know whats causing this...any help is appreciated , thanx in advance...dimitri

my guess:
one of those gauges or other component under the dash that is connected between power and ground, has shorted out. It no longer has any resistance so it is carrying full available current until the wire glows and melts or burns.

There should be a main fuse or breaker feeding the helm, but before the 1990's it seems boat wiring was not very professional or that may have been bypassed at some time.