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Thread: Lightweight spreader pole

  1. #1
    Join Date
    May 2012
    Location
    Oslo area
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    40

    Default Lightweight spreader pole

    Not many participating here nowadays..... But as I believe in also supporting the smaller internet sites, I will continue a bit longer.

    If the concept of a prototype lightweight spreader pole interests you, have a look at the https://sy-ls.blogspot.com, Teknisk tab.

  2. #2
    Join Date
    Jul 2009
    Location
    Gosport
    Posts
    348

    Default Re: Lightweight spreader pole

    Nice bit of'Upcycling' !

  3. #3

    Default Re: Lightweight spreader pole

    Quote Originally Posted by Lucky Strike View Post
    Not many participating here nowadays..... But as I believe in also supporting the smaller internet sites, I will continue a bit longer.

    If the concept of a prototype lightweight spreader pole interests you, have a look at the https://sy-ls.blogspot.com, Teknisk tab.
    Quiet but we are still here. We are wide enough to not require a pole but I have seen the tops of raised dagger-boards used to support shorter poles. They are high enough above the deck for down hauls to keep the pole down to be effective.

    Peter

  4. #4
    Join Date
    May 2012
    Location
    Oslo area
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    40

    Default Re: Lightweight spreader pole

    For the spreader pole I find a downhaul unnecessary, using the barber hauler hooked to the genoa clew works fine. I also thought our boat was wide enough, but without a pole there is nothing stopping the barber hauler and sheet from moving inwards during unstable winds. Thus the genoa was unstable around the 150 degree appearant wind angle, and the sail less effective. And, when sailing a Privilege, we all need the most out of our sails to get moving.

  5. #5
    Join Date
    May 2012
    Location
    Oslo area
    Posts
    40

    Default Re: Lightweight spreader pole

    When touching the subject of AWA around 150 degrees, there is something I have wondered about for a long time, but never seen mentioned anywhere. Lets say you pull the genoa real tight with the barber hauler in the correct position on the side deck, maybe also with a pole. And the wind is in the area of 150-140 degrees AWA. Looking at it from a wing aerodynamic point of view, if the wind is fairly strong, you have transformed the sail to work in the opposite way of normal sailing. The leech is now the luff. The luff is the leech. The wind passes over the sail from behind, and creating the same effect as when you are close reaching? To me it seems like the genoa is quite effective in brisk winds when set in this way. Anyone else observing the same? Looking at the drawing, where an average shape of the sail is marked, it would seem like the lift vector would be beneficially downwind. (?)



    Attached Images Attached Images

  6. #6
    Join Date
    Jul 2009
    Location
    currently Columbia/Panama
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    352

    Default Re: Lightweight spreader pole

    The drawing has the jib on the leeward side of the boat. Most jibs will not be able to get the leech tight enough, and the huge camber in the sail located closer to the luff would have the air stalled and detached on the backside. If there were any lift vector, it would be very small.

    On the other hand, we have a camberspar jib, which is a smaller full-batten jib with a half-wishboom spar built into it. When set, it is sprung tight like a windsurfer sail, and the sail shape remains pretty constant. It will set to the leeward up to 80*AWA, at which point it is performing somewhat like you suggest.

    Mark
    Mark Cole
    Manta 40 "Reach"
    www.svreach.com

  7. #7
    Join Date
    May 2012
    Location
    Oslo area
    Posts
    40

    Default Re: Lightweight spreader pole

    Maybe the drawing is not good enough, but the wind is supposed to come in from the port side, so the jib is not on the leeward side. The main is set to the opposite side. When set like this, the genoa will stay in shape around the 150 degree AWA, especially if supported by a pole.



    (Sorry for the other .jpg's, they uploaded without me intending it. Disregard them)

  8. #8

    Default Re: Lightweight spreader pole

    There are a couple of un-intuitive things that happen at these angles. We run with a screecher (Code zero) on a proder and a jib. With the wind 160-175 to port we fly the screecher on the port side and the jib on the starboard. Because the jib is inboard of the screecher it feeds air into the screecher and keeps it full. As the apparent wind moves forward the jib also maintains a good shape and can be sheeted in.

  9. #9
    Join Date
    Jul 2009
    Location
    currently Columbia/Panama
    Posts
    352

    Default Re: Lightweight spreader pole

    Oops, substitute windward for leeward in my above posting. The rest of the post is still what I meant.

    Mark
    Mark Cole
    Manta 40 "Reach"
    www.svreach.com

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