Kickup rudder critique

Discussion in 'Multihulls' started by Scuff, Nov 8, 2021.

  1. guzzis3
    Joined: Nov 2009
    Posts: 659
    Likes: 104, Points: 43, Legacy Rep: 42
    Location: Brisbane

    guzzis3 Senior Member

    0012 seems to be a common section. I for one would love to see whatever you care to share. Looks are subjective I guess but I don't mind the art deco lines. At least they don't look like a block of flats (apartments).

    Ultimately I rejected the Horstmans because the accommodation is all in one. Trimarans like monos give little privacy and separation until you go very big. I'm also not fond of the masthead rig.

    I would be especially interested in a sailing report when you get it wet. Either way good luck :)
  2. tropostudio
    Joined: Dec 2014
    Posts: 30
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    Location: St. Paul, MN, USA

    tropostudio Junior Member

    Regardless of any structural issues, if the concern is to get a more balanced rudder (lighter helm/less 'feedback force') you put the CE of the foil in front of the pivot axis of the pintles and gudgeons. Moving the top pintle back to make for a vertical rudder on a raked transom does this. The equivalent could be achieved by putting more of the rudder area in front of the pivot axis on the sloped transom of the Horstman. A Really Rough rule of thumb is 2D foil sections have a moment center 25% behind the leading edge, which means it would be 100% balanced (no feedback, which is not desirable).

  3. jamez
    Joined: Feb 2007
    Posts: 529
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    Location: Auckland, New Zealand

    jamez Senior Member

    I had my foils CNC'd from laminated wood blanks I provided. Foil shape is NACA 63A010. Chord is 320 mm at the top and tapers down to about 250mm just before the tip radius. Its 30mm thick and 800 long, built of ply (in hindsight it should of been cedar) glassed with 10oz uni and boat cloth. Well its meant to be 800 long, but when I cut the blank it was easy to make it 100mm longer. So I did. When it broke after about 3 years I was able to reshape the top (and also added a crap ton of double bias) and re-use it. So now its 750mm long and I haven't noticed any difference loosing the 150mm, its still nicely balanced and steers fine.

    Please start a thread and post a few photos - it would be great to see more of a more traditional foam build as opposed to a flat panel kit type. The extended transom looks good IMO and could easily be cut down to half height for a boarding platform if so desired.
    Last edited: Nov 13, 2021
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