Ethanol?

[MarkNY]

Find a station that sells ethanol free gas and use it for your boat and other small engines. Your motors will thank you.
Here's the NC page for stations that sell pure gas.
Ethanol-free gas stations in the U.S. and Canada

[Royjulius]

If I were you I would just take it to the local shop and be done with it. It will get "magically" fixed by experts while you are at work earning the moola to pay for it. Swapping stuff out and guessing what the problem is, is time consuming and frustrating and I don't know about you, but I'm not getting any younger. Besides, you could be using your time deciding which lures for your next outing and tying them on.
I do agree with what was said above about pushing the key in. That is an electric choke and shouldn't be done with a warm engine. I found that out the hard way. It would act like my battery was dead if I pushed it in, turn it without pushing in and vroom! it starts. Only push in on the first start of the morning.

[MarkNY]

Ethanol has nothing to do with engines not cranking over at all. Sounds like bad battery connections or bad ground on main engine lead. Get a friend that knows engines, or spend some $ at a marine repair facility.

I kinda disagree with this, long term exposer to ethanol laden gasoline can and will cause problems with clogged fuel lines, carbs and injectors resulting in hard to start engines which in turn will cause the electrical connections to the motor to get too hot and turn brittle from excessive cranking resulting in low voltage situations. Ethanol is a huge contributor to further problems down the road.

[berudd]

Might help to define 'crank' and 'turn over'. I think some are interpreting that to mean that when you turn the key nothing happens. The starter does not engage and spin the engine. Is that what you mean or to you mean the start spins the engine but it will not start?