Position of rudder

Discussion in 'Boat Design' started by iaegmooh, Mar 15, 2011.

  1. iaegmooh
    Joined: Mar 2011
    Posts: 3
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    Location: Lancashire, UK

    iaegmooh New Member

    Hi all
    I have a 19ft cabin cruiser powered by a 8 hp outboard, I wish to fit an aux outboard for emergencies, The design of the Transom does not really allow fitting on to it so intend to mount it alongside the existing engine in the well.(after removing the 2 fillets and postioning the main engine to one side)
    Currently the rudder is fitted to the leg of the engine and the engine connected to the steering wheel via a teleflex cable. By putting the 2 engines in the well I will not be able to turn them for steering so intend to mount a rudder (or pair of) fwd of the engines, operated by the existing steering cable. Will this idea work or will there be problems having the rudder in front of the engines?
    [​IMG]
     
  2. whitepointer23

    whitepointer23 Previous Member

    can you fit an auxillary outboard bracket on the transom. it would be a lot easier.
     
  3. iaegmooh
    Joined: Mar 2011
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    Location: Lancashire, UK

    iaegmooh New Member

    As you can see from the photo access to the transom is not easy as there is the engine well and 2 side lockers to get over and if the canopy was up then i would struggle,also after lowering the outboard into the water i would stuggle to operate the it. The alternative idea is to mount the rudder on the transom but would involve more work due to the length of the steering cable
     
  4. whitepointer23

    whitepointer23 Previous Member

    fair enough, but i think you will be disapointed with the boats handling at the dock if you fix the outboard straight ahead.
     
  5. whitepointer23

    whitepointer23 Previous Member

    with larger engines at least you can use the paddle effect of the prop to kick the stern in but with 8 hp i don't think it would have much.
     
  6. Poida
    Joined: Apr 2006
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    Location: Australia

    Poida Senior Member

    In my opinion the steering will not be much good. I have an inboard and in reverse there is no steering because there is no flow over the rudder.
    Stand in front of a pedestal fan and you will feel the flow of air. Stand behind it you will not feel much at all.

    So, you need to steer the boat by diflecting the water flow from the prop.
    You didn't give the power of the auxillary. There was awarning from our local sea rescue about people using low powered auxillary engines that have no chance in hell of pushing atheir boat especially in rough weather, the time you are likely to have a breakdown.

    8 HP on 19' sounds underpowered to me anyway so you wouldn't want any less. If your aux is 8 HP, mount the both side by side and run both of them linked together fro steering. If one konks out you still have the other.
    An engine mounted off centre will veer the craft to the oposite side that you will have to correct with steering, using power you don't have to spare.

    Do you have a search and rescue in your area? A radio might be an easier option.
     
  7. Fanie
    Joined: Oct 2007
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    Location: Colonial "Sick Africa"

    Fanie Fanie

    I agree with Poida, fit proper motors. Rudders are a lot more difficult to steer with, you will be hugely disappointed. Fit one large motor, and an aux second motor for emergencies. The second motor should still be big enough for a limp home option even in poor conditions.

    The single big motor will be more economical, more powerfull, faster, lighter, etc than double motors, so worth while looking at. Have a look at how the outboards are mounted on sailboats, it may be an option for the second motor mount.
     
  8. iaegmooh
    Joined: Mar 2011
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    Location: Lancashire, UK

    iaegmooh New Member

    The boat is on a lake and the 8hp is plenty to push her along at max hull speed of about 6 kts The aux will be a 4hp, just enough to get me out out of trouble and back to the mooring. Have already used the lake rescue service recently after having an impeller failure mid lake in bad weather, hence the desire for an aux engine.
    As you can see from the pic the transom is quite high and think that without fitting a bathing platform to stand on then a outboard on the back will be difficult to operate, if it was inboard with the main there is no room for the 2 engines to turn so back to the rudder problem. I know that building a rudder setup may be a big job to get it all right so may have to admit defeat and mount the aux on the transom. position will be difficult to keep away from the main eng rudder and position in relation to the hull which is a tri running into a cat at the rear and would prefere a short shaft so I could use the aux on our dinghy
    [​IMG]
     
  9. Fanie
    Joined: Oct 2007
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    Location: Colonial "Sick Africa"

    Fanie Fanie

    You have plenty of space there. Something like this - as you can see the motor can be lowered by quite a bit, and raised enough to be out of the water.
     

    Attached Files:

  10. whitepointer23

    whitepointer23 Previous Member

    wish i had of thought of this.
     

  11. whitepointer23

    whitepointer23 Previous Member

    amazing, i should have thought of that to.
     
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