July 22, 2012

A kill-switch question

HAVING SEARCHED the advertisements in vain for an extra-long-shaft 6-horsepower outboard motor, I broke down the other day and bought a brand new one from the registered dealer.  I wasn’t impressed with the service. Among other things, I asked him two questions.

The first was: “Is there a fuel filter on this engine?”

“No,” he said.

There was, of course, as I discovered when I got home and looked in the owner’s manual.

The second question was this:

“How do I start the engine if the man driving the dinghy falls overboard, taking the emergency kill-switch lanyard with him?  How do I start the motor to get back to him?”

“Don’t know,” said the dealer. “I’ve never been asked that question before.”

It’s hard to believe that a man who sells new outboards for a living had never thought of that question for himself.

As you probably know, the coiled, red, kill-switch lanyard is meant to be attached to your wrist or clothing.  If you fall overboard it jerks a small semi-circular disk out of a switch on the front of the engine. That allows a spring-loaded button to close inward and stop the motor immediately.

But you can’t start the motor unless that little disk is replaced.  And there it is, dangling on the end of a cord attached to your driver floating 50 yards astern.

Now, if you look inside the engine cover you’ll see two thin wires leading to the kill switch. My bet is that the act of pushing in the switch, which happens when the disk is removed, either completes a circuit, grounding the spark plug so that it won’t fire, or it breaks the hot-wire circuit to the spark plug, thus preventing it from firing.

In the second case, I suspect there is a good chance that if you simply cut the circuit between the magneto and the spark plug, you’re likely to blow a diode or do some other permanent damage  to the engine.  So my guess is that the safety switch simply grounds the circuit to the spark plug and stops it firing.

That being the case, you ought to be able to get the engine going again by fiddling with the two wires inside the engine cover.  You’ve either got to cut one or the other, or maybe you should cut both and twist them together.

Does anyone a little better informed than my dealer know how to get the motor going again? Does anyone understand the actual function of the emergency kill switch?

Today’s Thought
There’s lots of people—this town wouldn’t hold them—
Who don’t know much excepting what’s told them.
— Will Carleton, City Ballads.

Tailpiece
“Waiter, there’s a fly in my soup.”
(16) “Ah, thank you, sir, the dog must have missed it.”

(Drop by every Monday, Wednesday, Friday for a new Mainly about Boats column.)

18 comments:

David said...

A shoelace, wrapped a couple of times around the switch button and pulled tight, will break the circuit that grounds the spark plug.

Don P said...

Hi John,
My(older model)8hp has a spare kill-switch clip, minus the lanyard, attached to the tiller. If yours doesn't you could easily make one out of a piece of plastic.
Another solution would be to attach the lanyard to the engine mount and make a second lanyard with a loose loop to go over the mid point of the first one. If you go overboard the clip will still get pulled out but will remain attached to the engine mount where it can be put back to work.
But, of course, the best solution is not to go overboard in the first place. Hold Fast John!

KevinH said...

I'm not sure which, - join the wires or (I suspect)separate them, but I would guess the guy in the water would probably like you to get to him pretty pronto and not waste time scratching around taking covers off and looking for likely wires. My remedy would be to have a spare disc/key hanging on a short lanyard tied to the motor. Not that I would ever have thought of doing that before you asked the question, but there you are. !

don w said...

i've done it simply by wrapping/tieing a shoestring sized cord around the killswitch button in exactly the same place where that red thing goes.
i also have a spare on the zipper of my foulweather coat

Anonymous said...

I carry a spare lanyard.

Anonymous said...

I carry a spare lanyard.

Rational Root said...

Surely the answer he should have given you involves neither twisting nor cutting wires.

Given that you can buy those kill switch tags for a couple of euro on ebay, buy a spare and tape it (with a short lanyard) to the engine, buy another spare and tape it (also with a lanyard) to the boat.

Buy a few and attach one to each life jacket.

I do appreciate your interest in how the engine functions, but if I have just lost a passenger over board, I don't want to start playing - open up the engine and cut the red wire. or NOOOOOO cut the blue wire, the blue wire.....

Anonymous said...

Carry an extra clip?

Douglas said...

John, when leaving my dinghy at the dock for a short while I used to take the lanyard with me to prevent some miscreant from going for a joy ride. It was of course only a matter of time before I left it at home, and much to my horror found out that it's very easy to simply pull the switch out with my fingers and go on my merry way. (I suspect a bit of 1/8" line would also do the trick.)

John Vigor said...

Douglas, my kill switch is pulled in quite strongly by a spring. It won't stay out on its own. Only the plastic clip prevents the switch going into action. As others have suggested, I either need a spare lanyard and clip, or else a piece of light line jammed in to create a gap.

Thanks for the suggestions, folks. You're all way ahead of my local outboard dealer.

John V.

Adam said...

I certainly learned a lot from this thread. But what happened to the oars?

doryman said...

On my small outboard, that kill switch is the only way to turn the motor off, which irritates me every time I do it. Why is a "safety feature" also standard operation? I leave the lanyard looped to the carrying handle, for all the reasons mentioned above and one day plan to wire a toggle switch in there.
Seems to me a safety feature should not create a potential emergency situation, but I'm often cynical about "improvements".

michael

John Vigor said...

Adam: Um ... er ... too obvious I guess. Too low-tech. But there are other considerations. Imagine a small keeler whose mainsheet gets tangled in the kill-switch lanyard and flings it overboard. No oars on board. Without the lanyard you might as well not have an engine -- unless you know the trick about using a shoelace or piece of light line.

John V.

Matt Marsh said...

The engineers who designed my '94 Johnson 30 had this figured out: It has a bracket moulded into the tiller, right beside the kill switch, that holds a spare clip.

On any engine that doesn't have such an easy-access spare, I'd keep a second lanyard close by (and a third in a locker somewhere, because the spare is sure to get lost when you need it.)

Matt said...

The kill button closes a circuit to stop the engine. The key on the lanyard keeps the circuit open thus allowing the engine to run. Unplug the wire leading to the diode; they typically connect with a spade connector.

Matt said...

...ammendment, disconnect the wire from the switch to the magneto.

Belinda Del Pesco said...

Very informative post - thanks so much for writing it, and thanks to all the comment authors for their replies. Great topic.

Anonymous said...

@doryman they did that so if your "safety feature" were to fail and you were unable to shut the engine off, you would become flustered and have it repaired. Manufactuers way of forcing you to have a working lanyard.

@matt you were right the first time, don't bother with the magneto follow the two wires behind the switch, youll find both wires have plugs, unplug both or one and the engine will start.

Fyi you should unplug these if you have a no start no spark condition, to eliminate your kill switch as the problem.

@ john vigor The best place to keep a spare lanyard is under the hood, fastened inside the cowling with a spare pull start cord.

For anyone who might complain about removing the engine cover, you should know how to do it in an emergency anyway, if someone has fallen overboard you won't be concerned with putting back on immediatly anyway.

Manoverboard, pull engine cover, install emergency lanyard, restart, retrieve man, re cover engine.

Uncover, recover, re-cover

Sincerely anon