boat starting issue (electrical) 87 ts6m

[cmanning816]

I picked up a non running 1987 supra comp. ts6m for 1500$ I will be bringing this boat back to life.


I got the boat running after some plugs and wires were replaced after a day on the water boat was cruising at around 35mph for about an hour.
I get back to the dock and turn the boat off and tie up to get trailer. when I come back to start the boat nothing happens no start all accessory lights bilige and all work but no start.
I did notice that the volt meter on the dash was only reading 12 under full throttle so I thought the battery (optima red top) had died.
so I get the boat home and throw a fresh redtop on it and the starter solenoid engages and the starter runs away. I had to disconnect the battery to get it to stop.
so I didn't know if it was the starter solenoid or the ignition so I replaced them both. after the replacement I went to start the boat the starter solenoid melted.
so I jumped my ignition so I just had a single switch to the starter solenoid and same thing it just starts to heat up.
I can get the boat to turn over (the right way) but starter is dragging horribly and the external starter solenoid and the wire from solenoid to battery is melting.
I have replaced cables as well with no different results.


any info or related pics for the relay/wiring of a working boat would be much appreciated I have been at this for a month now going in circles thanks in advance