Ignition issue

Hello all,

i recently was gifted a boat boat which wasn’t winterized last year. I’ve checked the oil other than being full it doesn’t look like water has gotten into it. My problem right now is the boat will not turn over. When I turn the key I just get a single click from the 50amp breaker connected with positive battery wires. The breaker says to push to reset. When I try and push the button it does not push in. Would it be safe to say this is an issue or could it be the solenoid? Please let me know if you have any further questions to help

If the breaker is popping. Then there is a short to ground somewhere in the start circuit. When was the boat last run?

you sure its a breaker and not the slave solenoid clicking when you turn the key. If well above the full mark ,water is on the bottom of the oil. pull a sample from the dipstick or remove the oil pan plug for a sample.
Locate the slave and jump the 2 large posts, starter should spin the motor . Were the block and manifolds atleast drained?

I have a 1978 Mark Twain with a MerCruiser inline 6 and whenever I turn the key on I I have power to all my gauges and all my pumps but when I turn the key over to start it the starter does nothing but I can jump the solenoid over and the motor will turn over but the boat won't start I have checked my fuses they're all good.