Mechanical steering on sterndrive, anybody?

Discussion in 'Sterndrives' started by Nidza, Nov 28, 2019.

  1. Nidza
    Joined: Nov 2016
    Posts: 77
    Likes: 3, Points: 8, Legacy Rep: 10
    Location: Belgrade, Serbia

    Nidza Junior Member

    Hello,

    1. Does anyone uses no feedback mechanical steering on the stern drive and what experience you have with it? How reliable it is?

    2. What is the maximum torque that NFB mechanical steering can survive? I can see recommendations by manufacturers for quite powerful outboards.

    3. Can someone point me to the link how to calculate maximum torque on the steering wheel cable? Then I could correlate to some specs of available products if max torques are given.

    I am tempted to go this direction with diesel 195Hp/3000rpm and 1.6 times less propeller rpm (propeller D x P = 19 x 17, 3 blades, 65% BAR) on the stern drive to avoid maintenance of underwater hydraulics. Still I would like to hear main issues that could arise with mechanical setup in such a setup. Long cable could potentially be one of the issues.

    4. Am I missing something? Opinions?

    Thank you!
     
  2. gonzo
    Joined: Aug 2002
    Posts: 13,609
    Likes: 382, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Mechanical only cable steering has been used successfully on sterndrives for decades. There is no need for calculations. The no-feedback is used on non-powersteering installations. I don't know what you mean by underwater hydraulics, since no component of the steering is located underwater.
     
  3. Nidza
    Joined: Nov 2016
    Posts: 77
    Likes: 3, Points: 8, Legacy Rep: 10
    Location: Belgrade, Serbia

    Nidza Junior Member

    Thanks for your reply Gonzo.

    Is it not truth that with only mechanical cable (without NFB) you would have to fight the force produced by the rotating propeller (e.g. you could not remove the hands from the wheel without the boat turning to one side)? When you say mechanical cable I do mean on non-power steering - fully manual. I thought that this NFB prevents prop to affect the steering wheel (and stern drive) position when you do nit hold the wheel.

    Regarding underwater hydraulics, I have a bit older type of stern drive manufactured by “Sternpowr” on which the whole steering ram (double acting) is mounted externally on the drive and fully submerged, together with two hoses connected to through hull fittings. It is PITA for maintenance because if something happens, boat has to be pulled out. This is also non-power rather manual hydraulic steering system manufactured by Hynautic (fairly simple and with low pressure -20-30psi). So one option would be to install different ram, mechanically connected above water together with hoses above water. Other option is going to mechanical setup. The thing is that stern drive is so simple device and only things that need to be “too” regularly maintained is hydraulics and I prefer more often sailing compared to unnecessary maintenance. This is my reasoning, but I could be wrong? I don’t care too much for auto pilot, it would be just one more thing for maintenance.
     
  4. gonzo
    Joined: Aug 2002
    Posts: 13,609
    Likes: 382, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    The small trim tab on the back of the anti-ventilation plate is used to counteract propeller torque. Properly adjusted the steering is basically neutral. I think that all Sternpower drives were for high performance applications, so lots of maintenance are expected. If it has external hydraulic steering, you will have to do a fair amount of machining and fabricating to install a cable steering. The cable will fail if you install it below the waterline. It is supposed to be connected to a tiller that actuates the sterndrive, outdrive or rudder.
     

  5. Mr Efficiency
    Joined: Oct 2010
    Posts: 7,760
    Likes: 273, Points: 83, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    If you are going to go to the trouble of modifications that allow above-water steering connection, you might as well make that hydraulic, as your feedback worries will be covered.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.