Eletrical Mayhem, Wizard needed

[tribal]

So to start with it's an old I/O a 89 5.0L [Ford] with an OMC Cobra leg.
The problem began this spring.When I started the boat cold everything worked fine but after it had run for a while and I restarted it the starter would continue engaging after the moter fired up.I would kill it, try over [happens 3 out of 5 times] and then continue on.
The boat has a remote starter selinoid that was original that I thought was the problem.I replaced this then started several times at home no problem [not really representing true running temp]
Today I took it out on the water again.Once again fired up fine cold and on the first restart.Second restart the starter ran on again once,killed it,restarted no problem.
We are now 10 miles down the lake in the middle of nowhere all by ourselves.The third restart the starter runs on.I turn the ignition off, still running [starter and moter].I then turn off the battery Perko switch and kill it.We now try disconecting the ignition and turning battery on,still turning over wildly.
We disconect the starter lead, turn on the battery, and touch the lead to the terminal and the boat fires up with the ignition turned off.We cruise the 10 miles back with no issues, normal engine and electrical power and all instruments working.
When we get back and I go to turn the battery off and the engine keeps running with the electrical power on the guage varying wildly.I had to pull the lead off the distributor to kill the engine.

Help!!!

[RadDad]

Disconnect the pos lead to tne starter & take key out of ignition then check voltage on the solenoids terminals that connect to ign sw ( the small wires). If you're getting a reading then your ignition pos wire is shorted to another pos wire somewhere between ign sw & solenoid. You'll probably have to check visually fro ign sw to solenoid or replace wire to solenoid. Hope this helps.

[RadDad]

Forgot to mention, if you haven't already checked, it could be in the ign sw itself. Disconnect wire from battery to switch, if this stops the starter from turning over replace the switch.

[tribal]

So I've worked my way from the ignition all the way back to the starter selinoid disconecting conections looking for shorts.I continue to have ignition power [when the connections are all together back to the gauges] and constant power to the starter even when I'm disconected right back to the selinoid.
So all that's left is the battery to the Perko to the starter selinoid.From here it's putting power out always.Sounds like the selinoid but that's what I just replaced without a change in symptom's [though now it's way worse]

[tribal]

So it's the starter selenoid.I isolated it down to just the battery to the selenoid to the starter.There was still power going to the starter.When I put on my old selenoid [which wasn't working as bad] there is no more current going to the starter.
My question now is, what's making the selenoid crap out?I've looked over the grounds on it and all my wiring looks good [I can't find any bare wire for shorts].The wiring looks in pretty good shape in general [for a 16yr old boat]
Any thoughts?

[grapic]

The large battery wire on the starter is supposed to always be hot. The small wire on the "s" terminal of the solonoid is only supposed to be hot when the ignition switch is turned to the start mode. It should not be hot when in the run position on the ignition switch.