Fitting a lanyard kill switch

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ChrisParish
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Boat Make: Zodiac c310
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Fitting a lanyard kill switch

Post by ChrisParish » 11 Jun 2018, 19:53

As part of trying to use my boat more I am getting it ready for using single handedly. This includes adding transom launch wheels and a lanyard kill switch.
I have fitted the wheels now and today I set out to install a kill switch to my engine. The engine is a 1992 Mariner 5hp short shaft with a remote tank. The engine has never had a lanyard style "dead man" kill switch but I figured it could't be too hard to fit one.
overview.jpg
I did a bit of research and bought one from Force 4 with the intention of replacing the existing push button kill switch with the lanyard one.
630435.jpg
This is where my problems started.
As you can see in the photo below, the back of the kill switch is very close to the bowl on the carburettor - too close for me to be able to fit the one I bought from Force 4.
carb.jpg
I started looking around the engine for other possible mounting options. I could drill a hole in the lid, but that would be ugly and would mean that I would have a wire which needs to be disconnected before removing the lid completely. This could only be a last resort.
I noticed a rubber bung in the side of the bottom cowl.
port 1.jpg
I removed the bung and discovered three holes, two countersunk 4mm holes and an 11mm hole in the centre.
port 2.jpg
Time to get out the vernier callipers and take some measurements
measurements.jpg
TO THE MAN CAVE! :drive

Step one - create an accurate model of the killswitch in CAD
killswitch.JPG
Now build a box around it and add the mounting holes as per the measurements taken from the engine
box1.JPG
box2.JPG
Looking good, so time to print it.
Preparing the file for print using Simplify3D
print prep.JPG
As you can see, it's going to take over 2 and a half hours and cost around 72p. With electricity it should cost less than £1 :D

Hit print and wait for best part of 3 hours.....
printing.jpg
Done!
printed.jpg
The parts needed a little bit of cleaning up and fettling as they were printed for strength rather than surface finish. I can stamp on it without breaking it so it should be plenty strong enough.

I dry fitted the parts using some M3 stainless bolts and nuts which I had lying around and everything fitted very well
dry install.jpg
Add the wires and tighten everything up
final install.jpg
Now I need to splice into the wires from the existing kill switch so that I can wire the new one in parallel (so each switch works and either can kill the engine) I need to cut the brown and black wires and attach the two green ones which lead to the new switch. I used crimp connectors as solder isn't good in a high vibration environment as it cracks and breaks.
spliced wires.jpg
I tested the circuit with my multimeter to make sure that both switches worked without having to fire up the engine.
Having confirmed that it worked I glued the lid onto the box using cyanoacrylate (superglue).
glued.jpg
Reassemble the rest of the engine, stick it in a bucket and test! It worked perfectly.
finished.jpg
I went out this afternoon on the Itchen in Southampton and tested it in a real life situation (by pulling it - not by falling overboard!).

All in all I feel this is a successful mod and one I am very pleased to have done. :yay
These users thanked the author ChrisParish for the post (total 3):
chris moody (11 Jun 2018, 20:07) • Paul (11 Jun 2018, 20:39) • Martin (12 Jun 2018, 16:05)
Not a complete idiot - some parts are missing.

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Paul
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Re: Fitting a lanyard kill switch

Post by Paul » 11 Jun 2018, 20:46

Fluff me, how cool is that :clappy
Wish I had your expertise :mrgreen:
:cheers

acidcloud
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Re: Fitting a lanyard kill switch

Post by acidcloud » 11 Jun 2018, 20:55

Pretty Cool printing

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ChrisParish
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Posts: 275
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Boat Make: Zodiac c310
Outboard: Mariner 5hp 2 stroke | Mariner 9.9hp Four Stroke
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Re: Fitting a lanyard kill switch

Post by ChrisParish » 11 Jun 2018, 20:55

Ich bin ein NERD!
:lol:
Not a complete idiot - some parts are missing.

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Martin
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Re: Fitting a lanyard kill switch

Post by Martin » 11 Jun 2018, 22:16

Bloody hell Chris.. more talents 😳
Well done buddy 👏👏👏
F-RibsAndSibs.Com.... :whistle
Because it's a big old WWworld out there :mrgreen:

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Cliff
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Re: Fitting a lanyard kill switch

Post by Cliff » 12 Jun 2018, 15:36

Great problem solving, well done :clappy

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Steve
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Re: Fitting a lanyard kill switch

Post by Steve » 13 Jun 2018, 08:26

Amazing, we’ll done! :clappy

Now I need to up my game...

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