DIY electronic throttle and gearbox control

Discussion in 'OnBoard Electronics & Controls' started by CDK, Apr 3, 2008.

  1. CDK
    Joined: Aug 2007
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    CDK retired engineer

    This is an electronic control system I constructed a few years ago for twin Mercruiser engines. At the time I substituted the stern drives for Berkeley jets and discarded the old throttle control and bowden cables. Because of the required forces, the cables would not have been able to shift the jets even if they had been in perfect condition, but they were severely corroded and allowed no precise throttle control.
    I installed one 12 wire cable for throttle control, fwd/reverse shifting, trim and trim control.
    The jets were a disappointment regarding efficiency, steering and corrosion, so were replaced by DIY tunnel drives (Surface drives, this forum) and the Merc's are now replaced by VW turbo diesel engines (DIY marinising, this forum).

    The control system was the only part that performed well, so it is used again for the new power plant, albeit with small mechanical alterations to mount the actuators on the diesel engines.

    The whole may seem rather complicated when compared to a double Morse control and bowden cables, but it performs better and takes up much less space at the console and under it. In my opinion, for boats over 25 ft. an electronic system is a better solution than a bundle of bowden cables. And, last but not least, the whole system as a DIY project costs approx. $150 using new parts obtained from surplus shops like windshield wiper and fan motors, automotive relays etc.
    One might argue that the necessity of a 12V supply reduces reliability, but that is also the case for the engines that need at least 80 Ah batteries for preheating, cranking and opening the fuel valve, while current generations even have electronic injection.
     

    Attached Files:

  2. lazeyjack

    lazeyjack Guest

    good fer you like your attitude, but jus for the ref, a bowden cable is 1x19 wire, , you mean Morse(type) cables:)) good luck the electronic stuff cost squillions so maybe you can start production, for myself morse is fine
     
  3. CDK
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    CDK retired engineer

    I don't quite understand the point, Lazeyjack. The bowden cable is invented by Sir Frank Bowden (died 192?) as a principle to convey linear motion between two mobile objects. It can both be solid or stranded. Morse invented a now almost obsolete alphabet.
     
  4. CDK
    Joined: Aug 2007
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    CDK retired engineer

    The silence after submitting this post was deafening, so I take it that each and everyone of you prefer mechanical throttle and gearshift. But I'm not the only one who cooked up something electronic.
    Morse offers their ETC electronic throttle control, but they assume you own something like a Sunseeker 43 or larger, so you have to pay through the nose. BMW, Mercedes and even VW have adopted electronic throttle systems on their luxury models and even an Airbus 320 totally relies on fly-by-wire systems.
    The advantage in a boat is that it is very simple to install multiple controls and to synchronize two engines.

    When I adapted the actuators I made for Merc gasoline engines some problems arose. Space near the diesel injection pumps was cramped and the diesels, especially when idling, try to shake off anything that isn't fixed with at least three bolts. So I put the whole concoction in two plastic boxes, to be screwed against the bulkhead and used short bowden cables to do the mechanical work. I also added a limit switch that is actuated by an eccentric disk in case the leads to the cockpit should become shorted or open. The switch cuts power to the electric motors so they can't ruin the mechanical parts or burn out. And I added two LED's that I hope will never light up: they show whether it is a short or an open circuit. A pushbutton reset switch is there to bring the controls back in theit normal range once the problem has been resolved.
    At the first trial run, the system wasn't stable: the throttles were constantly moving back and forth and opening the starboard throttle reduced the port rpm. This was caused by a voltage drop over the 20 ft. supply and control cable, particularly the ground wire, so I split the ground in control ground and power ground, the latter being attached to an egine block directly.

    I've added a picture of the actual devices before they were installed. The modified windshield-wiper motor can pull 15 lbs in this setup, where only 6 lbs are required to pull the pump's lever, cable friction included.
     

    Attached Files:

  5. Fanie
    Joined: Oct 2007
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    Fanie Fanie

    Hi CDK,

    I like electronic controls. When designed and built well, nothing beats them.

    There are many apps where a mechanical setup is less desirable and way more expensive than ie wired or rf remote control.

    Fear for the unknown... most people have very limited knowledge of electronics, never mind complicated circuitry interfacing with mechanical drives and feedback, and all those wires, good grief :D

    He-he... BTW, your electronics suck :D There are way better components to use than those and easier to do H-bridges to drive motors with ;)

    Also, most people have limited knowledge of ie the batteries they use aboard, usually three days aboard a battery dies due to non-charging and everyone goes in a panic... you can't push-start a boat ;)
     
  6. Fanie
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    Fanie Fanie

    You should do sensing at the target, and send the information via a digital signal back. That way you won't have problems with voltage drops over long wires ;)
     
  7. CDK
    Joined: Aug 2007
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    CDK retired engineer

    I know how it should be done, but I've only a shed full of rather old-fashioned parts to chose from. When I closed down my electronic parts wholesale division 14 years ago, I loaded the remaining stock in a truck and moved to the sunny Adriatic where I enjoy retirement.
    The analog servo with just a dual opamp works perfectly now that I've split the ground connections.
    Thanks for your feedback.

    Cornelis Koger
     
  8. Fanie
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    Fanie Fanie

    There's nothing wrong with those components. The most important is that since you're the one that will maintain it, it would be better that you know what's going on in there. I guess we that use processors are just spoiled in using these things, but it does have the disadvantage that you sometimes miss the basics.

    I had a similar electrical remote control om my own boat. It worked and everyone wanted to knoe where the steering wheel was. Didn't think anyone would notice. I'm thinking of having a similar setup in my cat, but with rf data Tx & Rx. Haven't thought it through yet, but it would simplify wiring etc when the boat gets assembled.

    Maintaining the batteries over a long period of time on the water is one concern.
     
  9. Fanie
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    Fanie Fanie

    Hi CDK

    Sorry about the comment on your electronics. It looks rude now that I look back at it. The intention was to pull your leg but it came out pretty bad :eek:

    If you can find it in you to forgive me, we could maybe exchange a couple of circuit ideas and mechanical ones as well...
     
  10. CDK
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    CDK retired engineer

    No harm done, Fanie. I've also written things in this forum that in retrospect could and should have been phrased slightly different.
    Dutch is my 1th language, then comes English, German, Croatian and a bit of French: I think I am entitled to some rudeness now and then and accept that from others as well.
     
  11. Landlubber
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    Landlubber Senior Member

    Hi fellas, one point about the electronic systems, they do not fail safe!

    Another thing, when they fail you still need a mechanical means to control, so why not just have a mechanical system in the first place.

    Now having said that, i install only electronic systems now (owner demands), and also because the electronic engines and gear boxes need them......
     
  12. Fanie
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    Fanie Fanie

    Hi Landlubber,
    Anything can fail, electronic or mechanical. One can overdesign electronics as well to make it almost bullet proof, and you have to admit it is more elegant, easier, faster, space saving, even more economic amongst other things. Electronics found a place in our lives we cannot do without any more.

    Just try keeping the tv or pc off for a week ;)

    It may well be possible to have an electronic backup as to the mechanical one then
     
  13. Landlubber
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    Landlubber Senior Member

    Fanie,

    You missed my point, they do not fail safe, this means that when you are docking the boat, and it fails just as you are entering the berth, well it will keep on going......usually up the pontoon and into the next door neighbour. There have been already numerous occassions that this has happened.

    The mechanical systems do not tend to fail unless many years old, and of course neglected, electrical systems are very reliable, until they fail....which is usually in the first twelve months or not at all....they tend to last for decades if built from quality components, and one would assume that Teleflex More would be interested in using quality components, they are actually made in Japan. home of the best there is.
     
  14. Meanz Beanz
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    Meanz Beanz Boom Doom Gloom Boom

    I had dem cables fail... no fun, not a frequent event thank gawd. I had a mechanic install a new Morse steering cable in reverse once. Didn't notice until we hit full throttle and about 25 knots, man that was fun... what a spin ! Turn left and what the.....eeeek!

    Seriously, if is is done properly with sealed electronics and high quality actuators I'm not sure it would worry me too much.
     

  15. CDK
    Joined: Aug 2007
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    CDK retired engineer

    Last year a friend of mine entered the bay with his 37'sailing boat. When he approached the pier he pulled the throttle back, but the cable sleeve came loose in the control unit, so the engine went on at 2000 rpm. Full rudder and the kill knob saved him from crumpling up, but it was a close call. So much for mechanical controls.
    Of course I approach the mooring with bated breath until the system has proven to be reliable, although with twin engines a double failure is highly unlikely. And if something goes wrong, there are always the ignition keys.
     
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