Drilling hole in rudder blades

Discussion in 'Multihulls' started by Jethrow, Apr 4, 2019.

  1. Jethrow
    Joined: Jan 2011
    Posts: 6
    Likes: 1, Points: 3, Legacy Rep: 10
    Location: Sydney, Australia

    Jethrow Junior Member

    Hi all, just canvasing for opinions.

    I have dagger blades for rudders in my 30' catamaran, they probably weigh about 8 - 10 kg's each. Currently I remove the blades and lay them down in the cockpit when not in used. Problem is I think they actually get more damaged this way as they are underfoot in the cockpit and exposed to the sun directly and it's a bit of a pain removing them each time. I currently lash the blades through the top handle to the tillers to stop them lifting or falling when sailing.

    My thought is now to leave the blades in the cassettes when not in use and pin them to hold them up when not in use and also pin through the top to hold in place when sailing.

    Now my issue. The hole to pin the blades when up will obviously be in the water when sailing. Having the pin on about the centre of gravity will support the blade better but put the hole further forward. Hole further back will put it in the turbulent area but put more load on the blade. I can mitigate things a bit by making the hole as clean as possible (no countersinking to help locate the pin).

    So what do you reckon? Where to drill the holes?
     
  2. JamesG123
    Joined: Mar 2015
    Posts: 655
    Likes: 74, Points: 28, Legacy Rep: 10
    Location: Columbus, GA

    JamesG123 Senior Member

    You'll only need a 4mm or so solid pin, 6mm if you're a belt n' suspenders kind of guy, that can support that if in double sheer (drilled all the way thru the box). The drag induced will be insignificant, less than your average thru hull. Unless you are racin' and keep your bottom squeeky clean, the convenience vastly out weighs the negligible performance impact. Just put them where its easiest to get at.
     
  3. Jethrow
    Joined: Jan 2011
    Posts: 6
    Likes: 1, Points: 3, Legacy Rep: 10
    Location: Sydney, Australia

    Jethrow Junior Member

    Yeah James, that's the way I was thinking, I just didn't want someone to say "NO NO NO, don't do it. I did it and it caused a catastrophic cavitation"! :D
     
    Manfred.pech likes this.
  4. luff tension
    Joined: Aug 2010
    Posts: 62
    Likes: 5, Points: 8, Legacy Rep: 10
    Location: auckland

    luff tension Junior Member

    I have cassette rudders and use a thin teak wedge to hold the blades up while moored.
     
    JamesG123 likes this.

  5. JamesG123
    Joined: Mar 2015
    Posts: 655
    Likes: 74, Points: 28, Legacy Rep: 10
    Location: Columbus, GA

    JamesG123 Senior Member

    That is brilliant.
     
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