Sparking and starting but no key

It appears I am cluttering the forums today...sorrry, but when out this past weekend after an oil change boat seemed to be running great. Let the wife cruise for a while.....turned out to be a big mistake. I met up with her from a friends boat with our boat off. She mentioned it had made a strange sound just before turning it off. She described it as the engine revving than going really low so she shut it down. I got in got three really slow cranks then absolutely nothing. So my thoughts were alternator or battery. Battery is brand new so I was pretty definate on the alternator. Had a friend hook up cables with me on his 79 for about ten minutes, still nothing not even a weak crank, or needles moving, etc. He towed me in. Put the charger on at home and every time I plugged it in it kept spiking up and down and sparked hard when I pulled the positive on and off....more than it should normally. I immediately removed from the boat and put on the charger by itself and sure enough it was dead (alternator?). After a good charge when trying to reconnect to the boat it would crank the engine and spark everytime. I removed the key still the same thing. My thoughts were igition switch, starter, voltage regulator? Any help would be appreciated.    

Got it, thanks. I will send back my findings.

I have an update on my post. I was able to put a good charge on my battery, put the key in the on position and put cables to battery, which started the boat. Turned key off and starter continued spinning. Would this indicate a relay and/or starter replacement? Relay he indicated could be stuck in the "on" position? I was told this by a mechanic as a possibility. It is difficult to check voltage with and ohm/volt meter considering connecting the battery starts the boat?


Possibly voltage regulator? He was not sure since it is a boat and the year of the motor and it's set-up.

Got it. The mechanic is family and he was trying to help eliminate possibilities and time by just replacing the relay, but it does not sound like his idea is right for the application. I will follow the above mentioned. Thank you for the correct approach, I am guessing it has been some time since he has worked with electrical (not a current mechanic), but does know older style engines pretty well. Will be helping me with replacing or rebuilding the fuel pump I mentioned in a separate post.