Mercruiser eletrical short in the engine

[Buff2u]

My 88 Baja has been having starting issues for sometime now, I have replaced the slave solenoid, master breaker, the ignition switch, and a new battery. I am finding that my battery posts are very hot melting the plastic caps, and the cannon plug has some blue spark burn on them. There is a short that is popping the master breaker immediately. Any help would be greatly appreciated.

 

[Buff2u]

Oh and by the way, the boat will not start, it ran fine when we first put the new battery in. Ran it for a while at home with mufflers and took it to the launch dropped it in it started up just fine, got to our dock, went to go for a ride a few days later it stated fine but as we backed away from the dock it stalled. Replaced slave solenoid and it started up then died replaced master breaker and still nothing. Just thought i would tell the story behind the post. :rolleyes: