As everyone else has said, don't leave your boat in the water without an automatic switch. Also, don't leave it at the dock without plugging in the shore power and turning on your charger. If something like LEfriend mentioned happens and nobody notices or there's heavy rain you'll have a problem on your hands.

And, credit to Wakina on this one, clean your bilge regularly during mayfly season. Those little suckers will burn out a pump in a hurry.

Just as an aside, our boat has a self draining deck and technically shouldn't ever have any water in the bilge. It always had water in there last year and it took us until the end of the season to find the leak. If our pump wasn't automatic or we didn't leave the on-board charger plugged in while we were away we might not have a boat that floats anymore.