Ok, so I've read the responses on here, and I've done a bit of research on the internet on how killswitches work... cause I really don't know anything about them. However, something I should have mentioned was that when there was a little water in the bottom of the boat, one of the belts was splashing the water upwards. I really don't know how the wiring of the killswitch connects to the motor, but I feel like somehow the water splashing upwards and disconnected something, or shorted something out, with the killswitch. I could be completely wrong. But yeah, I feel like you guys are more on the right track with the killswitch idea than the battery.
Anybody know whether water splashing upwards would do anything? Or how that could be fixed (if this is the cause of the problem). Also, would this maybe be a problem with the iginition switch? Could the water cause the same problem with an ignition switch?