New Ruddered Boat from NDK/SKUK with Interesting Rudder Design and Features

Discussion in 'Gear Talk' started by semdoug, Nov 25, 2017.

  1. semdoug

    semdoug Paddler

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  2. JohnAbercrombie

    JohnAbercrombie Paddler

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    Rudder details at:


    Same video at:



    In use, you would need to ensure that the rudder was exactly centered before trying to retract it into the slot- a problem designers have been wrestling with for years.
    The deploy/retract is via cords with a jam cleat near the cockpit - shown in the video; not so obvious in the still pic of the green boat.
    Slick boat - in the Epic 18X, Point 65 Freya, Thomasson Panthera line.
     
    Astoriadave likes this.
  3. dc9mm

    dc9mm New Member

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    No reviews of this yet that I can find.
     
  4. mick_allen

    mick_allen Paddler & Moderator

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    Altho not a review, before those vids came out I ran over several of the issues here:

    http://www.westcoastpaddler.com/community/threads/the-revo-rudder.7652/#post-87606

    The first thing to realize about this rudder is that is just another pinhead but with an additional constraint of a required “L” shape blade geometry to reach over around the stern, that subsequently is affected greatly upon retraction by the location of the rudder axis . . . and in turn that pivot point greatly affects rudder ‘yoke’ outer dimensions and in turn the rudder throw.

    The sketch shows some of the issues and possible design directions:

    Issues.jpg


    This style of rudder REQUIRES a vertical stern: pointy ended kayaks don’t work.

    • This is a pin-head rudder in that all the workings could be exposed to damage from external impact while retracted. The housing is however, streamlined to the hull shape so these possibilities are extremely minimized. And the lines and ‘tiller’ dimension is internalized. I like how it would be out of the way for tows and scrambles, etc.
    • it has none of the conceptual elegance that an auto-aligning blade has on retract as this is purely another hunt-and-peck rudder except it now originates far away from the water from the deck rather than directly from the hull.
    • A natural blade profile is compromised by the rudder post location on retraction, so the rudder shape [side profile] will have to be very thin and therefore possibly long to be effective. [long thin [high aspect] blades are flexible, weak, and most importantly stall easily].
    • With the above compromise as well as having hidden lines, rudder torque will be very low – or conversely the rudder will be very twitchy and hard to set as it would be very responsive to small line movements.
    • And because of the line concealment and possible line interference near the very ends of the kayak, rudder deployment angles will have to be kept low
    • note that one of the issues is that a wide blade shape requires a poor slot drainage shape such that cold weather paddling or storage might just be an issue, heh heh.

    At that time I didn't know what blade shape was to be chosen, but you can now see the compromises made:

    · very narrow blade [narrower than expected]

    · blade head not optimally braced within housing

    · housing pivot point moved sternward even farther than halfway, and

    · therefore low angle control with tight, hidden, lines a requirement and

    · only very small rudder angles able to be utilized which to some degree reduces the necessity for major centralizing.

    skuk-investigation.jpg
    The retract axis location shows that only half or less of the housing can brace the blade-head, as well as the rudder axis location being pushed so far back means that this approach could use some more serious design development, but . . . .
    Skuk-Blade&Pivot-desc.jpg

    . . . rudders are fun and it is interesting to contemplate the balance that various compromises require one to make to achieve the desired objective. While this rudder approach seems to be a bit of a jumble for now, with development in the future, for blunt ended kayaks, it seems like a reasonable approach.
     
  5. mick_allen

    mick_allen Paddler & Moderator

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    One of the general limitations that I referred to above is that the rudder 'yoke' dimension [in this case the housing width at that rudder axis] would mean less fine control of the rudder angles, however:

    If the rudderlines were crossed at the bottom front of the housing, they would resolve to opposite sides of the hull which means that the rudder 'yoke' dimension could actually be fairly decent [although max rudder angles would still be quite small].
     
  6. semdoug

    semdoug Paddler

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    I can't hear much of the audio. Is there any mention about the bailer? What is going on with the day hatch?