Are you booted?

I'm not talking about foul weather boots or your car being illegally parked, or your computer running here, I'm talking about some very important electrical terminals on your engine. In the photo above we see a classic and potentially dangerous situation. The white, high output alternator positive terminal in the center of the photo has no protective rubber boot on it. Even worse, and a little harder to see is the starter motor positive terminal shown to the right of it (partially obscured by the black rubber hose) with no boot on it....

18th February 2010.
By Ed Sherman

I’m not talking about foul weather boots or your car being illegally parked, or your computer running here, I’m talking about some very important electrical terminals on your engine.

In the photo above we see a classic and potentially dangerous situation. The white, high output alternator positive terminal in the center of the photo has no protective rubber boot on it. Even worse, and a little harder to see is the starter motor positive terminal shown to the right of it (partially obscured by the black rubber hose) with no boot on it.

 Most boaters don’t realize that the starter motor on their boat is the ONLY electrical circuit on their boat that is not required by the ABYC to have an over-current protection device (fuse or circuit breaker) installed in it. Most alternators won’t have one anywhere near the device either. We’ve had cases where underway in rough seas a tool box has inadvertently opened up and allowed a wrench or screw driver to bounce around in the engine space on the boat. If one of these or any metal object comes in contact with one of these unbooted terminals and also comes in contact with any other part of the engine sparks are going to fly! I’m talking about what we call a dead short circuit here, one where a heavy current will flow that can easily start a fire on board. In the case of the alternator, a fuse will probably blow shutting the short circuit off. But, in the case of the starter motor circuit, you’ll have to wait until the heavy cable supplying the starter motor burns up before you can count on the circuit shutting down. Odds are it’ll burn long enough to ignite something else in the area of the cable. As part of your spring check-ups get these terminals booted! The boots are available at the electrical department of West Marine or any good ships store and are really cheap insurance.


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Ed Sherman

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Ed Sherman is a regular contributor to boats.com, as well as to Professional Boatbuilder and Cruising World, where he previously was electronics editor. He also is the curriculum director for the American Boat and Yacht Council. Previously, Ed was chairman of the Marine Technology Department at the New England Institute of Technology. Ed’s blog posts appear courtesy of his website, EdsBoatTips.
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