I've started carrying a spare kill switch after what happened in a high school tournament a few years ago when I was a captain. Due to high wind and a boat wake a captain was throw overboard taking the kill switch with him,killing the engine. Boys were still in boat and couldn't get to him with trolling motor as wind was too high and they didn't know how to jam kill switch to crank motor. Captain was finally rescued unharmed but really cold by another boat, but if a spare switch had been handy they could have gotten to him much sooner. I've had one in my glove box ever since. Always used one but never thought about that scenario where a spare would be needed.