Okay, this is a really minor issue, but I can onl;y imagine it is going to get worse, so here's the deal:

When the boat is cold, when I trun the ignition to 'start' I get nothing ( I just hear a click from the engine compartment) 50% of the time. I have plenty of power in the 2x Optima batteries (12v surface, 13.2v @ idle, 1000 CCA each)

If I key trying the key, eventually it will crank. Once it warms up, it NEVER does it.

I have heard aboue the primary wiring harness at the motor getting corroded but I have not checked it yet, but will after much brow-beating from my chick...assuming the connections are not correded, what is the next guess?

Its a 2000' 500HP (carb).

TIA.

Possibly the starting relay. It was in my case.

I would check all the connections before I assumed anything else.

Double check the connections then take a look at the starter relay.
In some applications it's mounted on front of the engine, starboard side, along with a blue reset button for the Mercathode system. Best way to tell if it's bad is to bypass the relay by connecting the large leads together. Be careful beacuse the engine will turn over as soon as the those wires touch.

My 350 Mag used to do the same thing. Replaced that relay and all was right again.

I had an S-10 that did this. Turns out that the primary wire was too small. I installed a hot shot relay and never had this problem again. Sometimes when you buy a remanfactured or an aftermarket starter they require a little more zip from the ignition switch.

Roby

my guess it is starter relay...jump it before doing much else