yamaha 10hp strange thing

[tat]

Hello. This winter, my canopy tore and let in rain. I noticed the lid had come off my starter battery box and rain had filled it to totally submerge the battery (which also has a 40w solar panel attached).

I lifted the battery (standard sealed car battery) out, expecting it to be kaput, removed the terminal connecters, but it measured 13v. So I removed the solar connectors, put the outboard (1970s Yamaha 10hp) terminal connecters back on and turned the remote ignition key and instead of starting as it does every time, and just had done with the battery submerged, there was just a bit of a starter motor sort of whoosh click sound or something, but not a starter motor movement.

I removed the terminals and took a feed from the leisure battery (14v), but still nothing.

I took the engine cover off and measured at the starter motor and solenoid, getting a good voltage.

So what could be going on? I thought it would just start. Doesn't make sense.

I used the emergency starter cord, and it starts well enough.

So, I'm going to have another try next week.

Could i have damaged the solenoid? Should I try to fire the starter with a direct feed?

I do not know much at all re engine electrics. If you have a suggestion, please be as basic simple plain speaking as you can and consider me as a total beginner. Thanks. Doug.
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I put this up on engine board and have now moved it here because it is electrical.

So, I've been back and had another go.

I'm taking power from the leisure, using my car jump leads to get the reach.

So, I've a solenoid and the starter motor. The solenoid has two high voltage terminals and then two smaller voltage wires each independent of eachother.

So, I connect the jump leads to the starter battery cable. The negative end of this cable terminates onto the starter motor; the positive terminates to one of the high voltage terminals on the solenoid (lets call this the top one). Meter shows strong voltage between starter motor terminal and top solenoid terminal. I turn key and nothing happens.

So, I clipped neg jump lead direct to starter, and positive direct to the 'lower' terminal on the solenoid, and the starter worked.

So, I'm thinking that there must be a switch in the solenoid, controlled by the low voltage wires, which should make a connection in the solenoid between the upper and lower high voltage terminals. So I am thinking that that switch must be kaput, and i need a need solenoid. Does that make correct sense?
Thanks. Doug