Wing mast practice

Discussion in 'Multihulls' started by HASYB, Sep 1, 2012.

  1. HASYB
    Joined: Jun 2011
    Posts: 310
    Likes: 16, Points: 18, Legacy Rep: 143
    Location: The Netherlands

    HASYB Senior Member

    Thinking about the (re)construction of some parts on the Newick 8.5:
    I wondered how many degrees a wing mast must be able to turn in relation to the boat and to the boom?
    How many degrees the sail must be able to turn in relation to the mast?
    Can one depower the sail by over-rotating the mast?
     
  2. teamvmg
    Joined: May 2008
    Posts: 124
    Likes: 3, Points: 0, Legacy Rep: 22
    Location: christchurch,uk

    teamvmg Senior Member

    Over-rotating the mast would indeed de-power the sail by allowing a little luff curve.
    But over-all, it would power UP the rig by inducing camber to the mast/sail combination.

    The way to de-power a wing mast rig is to rotate the mast to point into the apparent wind.
     
  3. HASYB
    Joined: Jun 2011
    Posts: 310
    Likes: 16, Points: 18, Legacy Rep: 143
    Location: The Netherlands

    HASYB Senior Member

    OK, thanks.
    I asked because in the current situation the mast can only rotate 60 degrees in relation to the sail, that is 30 degrees either side. Is that enough? It looks to little.
    Also the shrouds are rather far back, I have a feeling there is not enough room to "play" the mainsail.
    On the other end I have no experience sailing these rigs/boats and probably have to live with it.
     

    Attached Files:

    Last edited: Sep 2, 2012
  4. warwick
    Joined: Jan 2012
    Posts: 423
    Likes: 7, Points: 18, Legacy Rep: 63
    Location: papakura south auckland new zealand

    warwick Senior Member

    Gary may be able clear up the rotation restriction on Steinlager 1. I think it may have been restricted to 90 degrees, 45 degrees either side. It may be under the historical multihulls thread.
     
  5. Gary Baigent
    Joined: Jul 2005
    Posts: 2,959
    Likes: 102, Points: 63, Legacy Rep: 509
    Location: auckland nz

    Gary Baigent Senior Member

    Hasyb, any rotation is way better than a fixed mast but since you have such a moving rig, then why not rotate it to gain the full benefit? - and that is to near 80 degrees either side, say 160 degrees total. A 30 degree rotation would only be of use sailing very close to windward in quiet winds, everywhere else you'll find that the leeward side of the mast to sail will be partially stalling. The mast needs to rotate enough to get a sweet curve leading without a step onto the mainsail on all points of sail . And to achieve that the rig does not have to be set up drum tight; you have to allow some slack so the leeward shroud doesn't bind and stop full rotation. And all the shrouds have to go to the leading edge beak of the mast, not with the side stays set back from the leading edge. That is why you have so limited a mast rotation at the moment. And if you're worried about a slack forestay, then you must have runners to keep the forestay tight.
     
  6. teamvmg
    Joined: May 2008
    Posts: 124
    Likes: 3, Points: 0, Legacy Rep: 22
    Location: christchurch,uk

    teamvmg Senior Member

    Hasyb. Is that the headboard or a batten slider in the pic? You might be ok if its the head board and the other sliders have more rotation
     
  7. HASYB
    Joined: Jun 2011
    Posts: 310
    Likes: 16, Points: 18, Legacy Rep: 143
    Location: The Netherlands

    HASYB Senior Member

    Thanks Gary for clearing that up, makes perfectly sense.
    Good excuse to also work on a canting system.
     
  8. Gary Baigent
    Joined: Jul 2005
    Posts: 2,959
    Likes: 102, Points: 63, Legacy Rep: 509
    Location: auckland nz

    Gary Baigent Senior Member

    Teamvmg, the "beak" pivots 30 degrees either side, just looked again, my fault for not checking it out propoerly.
    Hasyb, that has to be fixed solid pointing directly forward, imo. At the moment the leeward shroud would bind even worse, that is, presuming the pivoting hounds beak rotates to windward, pulled round by the tighter windward shroud. Maybe it pivots to leeward under load?
    Must say it looks a bit strange to me in that the leading edge appears very sharp, plus there is the V to allow the beak to move side to side, which is very un-aerodynamic. Have you got some other photographs?
     
  9. HASYB
    Joined: Jun 2011
    Posts: 310
    Likes: 16, Points: 18, Legacy Rep: 143
    Location: The Netherlands

    HASYB Senior Member

    vmg, that is the headboard, if that's the word for the top slider (squarehead main).
    The other sliders don't have more room to rotate the battens because they are limited by the fairings either side of the rail (rail is in a 5 cm deep groove)
     
  10. HASYB
    Joined: Jun 2011
    Posts: 310
    Likes: 16, Points: 18, Legacy Rep: 143
    Location: The Netherlands

    HASYB Senior Member

    Gary, the pictures are from the backside of the mast as vmg says.
    The plan for the winter is to extent the rail further outside (+/- 10cm) to allow the sail to rotate more in relation to the mast. perhaps also the change leading edge (a bit blunt now).
     

    Attached Files:

  11. Gary Baigent
    Joined: Jul 2005
    Posts: 2,959
    Likes: 102, Points: 63, Legacy Rep: 509
    Location: auckland nz

    Gary Baigent Senior Member

    Hielan, you posted the mast trailing edge top batten slider ... and I was thinking it was the mast front, relating it to mast rotation. Duh! Post us a shot of the front section, also hounds, mast bearing etc.
     
  12. Gary Baigent
    Joined: Jul 2005
    Posts: 2,959
    Likes: 102, Points: 63, Legacy Rep: 509
    Location: auckland nz

    Gary Baigent Senior Member

    Looks fine to me, stays to the mast front, should be no problem getting full rotation.
     

    Attached Files:

  13. HASYB
    Joined: Jun 2011
    Posts: 310
    Likes: 16, Points: 18, Legacy Rep: 143
    Location: The Netherlands

    HASYB Senior Member

    :D:D I hope the following is not lost in translation.
    1)The rotation of the mast is limited because the sail is only allowed to turn 30 degrees in relation to the mast (rail in groove).
    2) rotation between the boom/sail and ship is limited by shrouds.
    3) system to adjust rotation between mast and boom. If you look at the gooseneck you see the "ears" on the mast and on the boom there were pulleys in between to adjust the rotation, but also limited the rotation.
    Sorry for the confusion (my english) but I really think a lot of my questions are answered.
    Thanks a lot.
     
  14. Silver Raven
    Joined: Oct 2011
    Posts: 437
    Likes: 11, Points: 0, Legacy Rep: 67
    Location: Far North Queensland, Australia

    Silver Raven Senior Member

    Gooday 'HAS' Let's see if we can all speak the same language - shall we. What's the "wing" mast made of & what size is it ??? Please

    I suspect - by the picture of the boat - that what you have is a standard extruded alloy section mast. It is of a "wing" section shape - but it is not a 'wing-mast' - as such. If you look at the AC 45's & the SR 33's or even the 'C' class catamarans & the AC 72's you will see what a 'wing-mast' is. - or Gary might post you a pic of the 'wing-mast' on a 'B' class catamaran that I built back in 1965/6.

    Now re your side stays - they should come from a central point - in the very front of the mast at the same take-off point as the fore-stay is attached - - there is no need to go more than 400mm aft of the middle of the mast section - regardless of the section - size - shape - height - of the mast - even in 12 mtr to 18 mtr ocean going multihulls (as was done back in the mid to late 60's & still works to this day. To place the side stays any farther aft is just a total waste of mast-rotation available room because if you need to keep the fore-stay tight - as Gary says - install a pair of backstays - which are much more effective.

    What is the mast base rotation point - both in the mast & on the deck - made of - please ???

    The sail plan on you boat is really very simple & shouldn't need much effort to make it very efficient. Let's know how you're progressing, eh ??? ciao, james
     

  15. HASYB
    Joined: Jun 2011
    Posts: 310
    Likes: 16, Points: 18, Legacy Rep: 143
    Location: The Netherlands

    HASYB Senior Member

    James,

    Thanks for the reaction and yes I'm for understanding each other.
    The mast is a carbon box with foam fairings it's 11.00 meter long with a 30 cm cord and is 12,7 cm wide.
    Rotation points are male/female 8 cm wide steel rings in glass/carbon fittings.

    Splitting hair is not easy to understand and can be ground for extensive useless exchange of words I know; but I give it a try anyway.
    I speak of a wing-sail, when thinking of the "rigid" sails of AC 45, AC 72, C Class etc.
    Wing-mast I use when the mast is wing shaped mast followed by a more or less flexible sail.
    Sorry if my interpretation caused you any discomfort.

    Hielan
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.