I have a Challenger 28 DDC with an 8.1L and Cole-Hersee electronics, that has started itself when the key is "ON". Fortunately I was on the boat at the time and I was able to turn it off by turning of the key. It has done this several times. Also, I am concerned that the starter has engaged while driving the boat. Any ideas as to the cause? Has anyone else had this problem?

bad ignition switch,,bad slave solenoid or the solenoid on the starter is shorted..once you put it in gear the nutrial safety switch will eliminate the ignition switch if the starter is engaged..

Thanks for the info. I will check those items.