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Roger is back home from 80N

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  • Andres Espino
    For those of you like me who are sort of following the travels of Roger Taylor, skipper of a little junk-rigged Corribee called Mingming.... Mingming makes it
    Message 1 of 42 , Jan 1, 2013
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      For those of you like me who are sort of following the travels of Roger
      Taylor, skipper of a little junk-rigged Corribee called Mingming....

      Mingming makes it back to Whitehills after 3000 miles and 65 days at sea. 
      http://www.youtube.com/watch?v=ED9Hxe6qZo8


      He has posted that latest video on his youtube channel and there are many previous ones as well     http://www.youtube.com/user/junkming


      Learn more at his website   www.thesimplesailor.com

      Hope you enjoy it...

      Andrew


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    • Paul McKay
      It is always difficult to be clear without waving my hands about but I think you mis-understand. You already have the individual and combined C/E s from the
      Message 42 of 42 , Jan 3, 2013
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        It is always difficult to be clear without waving my hands about but I think you mis-understand. You already have the individual and combined C/E's from the profile drawing of the original Bermudan sails. It is relatively easy to mark the C/E of the proposed Junk sail with its mast position. By superimposing the C/E of the new drawing over the combined C/E of the original you can determine the new mast position on the hull.
        All this has given the static point of C/E. However when the boat is sailing the sails are at an angle to the centreline and are cambered so the individual and combined C/E's of the Bermudan will move forward and out to leeward of the centreline. By marking where the combined C/E now appears on the Bermudan by looking from above you can compare where the C/E of the new Junk Sail will appear as drawn from the 'New mast position'. Depending upon the amount of overlap of the front of the Junk sail the Junk C/E might be behind or level with the Bermudan C/E and it may be outboard or inboard. Since the C/E provides the thrust point the further outboard from the centreline the greater turning moment to windward. If you know how the Bermudan version sails you can now estimate how the Junk version will sail and whether your new mast position is far enough in front of the original mast position.

        There, I've stopped waving my hands!

        Regards, Paul


        On 3 Jan 2013, at 19:16, lself100 wrote:

        >
        >
        > Hi Paul,
        > This is the most convoluted method of finding the geometric CE of the combined (main & jib) sail area I've ever seen. What is the source? Why the 45 degree correction and outboard location? Is the derived CE supposed to be the "true" CE accounting for cambered sails?
        > Just curious about the background reasoning.
        > rself
        >
        > --- In junkrig@yahoogroups.com, Paul McKay wrote:
        > >
        > > Sorry Thierry, now that you have marked the combined C/E in profile view, imagine looking down on the boat from above. The C/E will be a dot somewhere along the centre line. Now still from above, draw 2 lines at 45 degrees to the centre line from the point of the original mast and the bow representing the original main and jib/genoa. If you mark the c/e of each sail and connect with a line the combined C/E will be a point somewhere between the ends of this line but will now have moved forward and outboard from the centre. If you repeat with your proposed sail c/e from the 'new' mast position you can check how they compare.
        > >
        > > When I measured the original lead of the Eclipse it was about 18% which I thought must be too much. (No internet in those days to check) So I blindly followed the advice from Jock McLeod's manual and fitted the mast to give 12 %. Anyhow, it worked.
        > >
        > > The height of the C/E is less of a worry in light winds and can easily be reefed down.
        > >
        > > Cheers, Paul
        > >
        > >
        > > On 2 Jan 2013, at 21:46, southcoveemail wrote:
        > >
        > > > Hi Paul,
        > > >
        > > > >You can double check by drawing the original rig in planform at an angle of 45 degrees. The combined C/E will have moved forward. Now check that against the C/E of your sail at 45 degrees.
        > > >
        > > > Sorry I don't get it.
        > > >
        > > > > When I converted my Eclipse 22 I re-fitted the mast to give me a 'lead' of 12 degrees. That seemed to give me a balanced helm.
        > > > >
        > > >
        > > > Did you change the lead from the original rig?
        > > >
        > > > I uploaded a pdf file in the file folder "AAA Thierry" with
        > > > - the Shark's original rig
        > > > - the intended sail
        > > > - the superimposed junksail on the original with the same CE location as the original and a lead of 11%
        > > >
        > > > If I keep the mast at the same location I get a 7% lead.
        > > >
        > > > The CE is also quite a bit higher depending on the height of the sail but I guess I shouldn't be too concerned as the reefing is easier.
        > > >
        > > > Cheers
        > > >
        > > > Thierry
        > > >
        > > >
        > >
        > > Paul McKay
        > > paulbute@...
        > >
        > >
        > >
        > >
        > > [Non-text portions of this message have been removed]
        > >
        >
        >

        Paul McKay
        paulbute@...




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