Ignition breaker problem

check your starter load.   If the starter is drawing too much current, I would imagine that the breaker would pop.   The other thing to check would be the wire connections. Extra resistance will cause the amperage load to go up when you hit the start button.

Steve, When you say you turned the key to start you mean all the way to start position when it kicked the breaker the last time right?

Take the starter loose and see if it clicks when you go to the start position. Could be a crappy ground wire back to the battery from the block too. A lot of times the cable ends look fine but over the years water has made its way down the cables and started corrosion near the ends.

The starter shouldn't click the main breaker because it draws its operating power directly from the hot battery lead via the positive battery cable.

The solenoid could be bad causing too much load during start position operation. All the main breaker does is supply all the power to the forward section IE the boat electronics. So if the main breaker was kicked off theoretically you could still get the starter to turn via jumping across the two large poles.

Giving this thread a bump. I had the same problem with the circuit breaker popping when I tried to start the boat this past weekend. Cleaning up the battery cables took care of the problem. Thanks Zach!