Ignition Circuit Fault?

Took the Moomba Mobius V 2000 out at the weekend.
Ran all day Saturday, no worries.
On Sunday, she started fine, then ....once we were getting ready for the first set, i switched her off, then try to restart.....NOTHING!
Checked everything.
Nothing out of the ordinary.
No sound heard at the starter motor coil upon ignition activation.
So, removed the starter motor (all done out in the middle of a river) bench tested the motor....no response.
Checked the solenoid of the starter, looked fine, tested , but nothing happened.
So, then i think there is nothing wrong with the starter, maybe the ignition switch, or the breaker on the ignition circuit, but it had not popped.
Gave up after 3 hours of trying.......rowed back to the dock.
Got her on the trailer, ready for home, thought i would just check....low and behold, started first click!!!! Gutted!

So......do i have a bad earth somewhere, or a faulty ignition breaker line.....or something else unknown?

I will carry a small length of wire from now on, to run the live from the battery direct to the solenoid, to cut out the switch and breaker, this would tell me where the fault is respective to the starter motor, but i don't have a set of electrical drawings for my boat circuits.

Is there any other relays/switches/sensors etc which may be causing this issue?