Flat, hinged or cambered?

  • 14 Aug 2018 22:20
    Reply # 6573796 on 461931

    I'd love to hear, too, Arne.  Alan (ZBD) and I both feel that camber puts a lot more stress into the sail, but as he sails engineless and, like most Trade Wind sailors, doesn't just sit in an anchorage and do nothing between passages, but goes exploring, he reckons the trade off is worth it.

    I want to achieve a cambered sail that has no loadings on the running lines, like a flat sail.  I really disliked the force required on the LHP to pull out the creases on Fantail's sail.  Paul's foresail on La Chica only required the slightest tweak.  David and I are hoping that SibLim's sail will be the same.

    The Aero rig has minimal stresses, but on the other hand it has lots of little bits that can fail, which would be tricky to fix on a small boat at sea.

    Articulated battens, if simple and stout and in the right place, in combination with flat sails are probably almost as robust and stress-free as a flat sail.  I'm not sure that I have the skills to make the 'hinges' however and I really can't afford to farm things out.

  • 14 Aug 2018 22:20
    Reply # 6573795 on 461931
    Anonymous member (Administrator)


    Flat or cambered for deep sea voyaging?

    Time for a revival of this old topic.

    Nowadays, it doesn’t seem to be controversial to put camber in junksails meant for coastal cruising. However, from time to time the question about flat versus cambered sails still appears when the matter of ocean travelling is up. The boat of the month is currently Chris Gamble’s 34’ schooner. He chose to go for flat sails and seems to be happy with that.

    Now, today, Asmat Downey reports that he has returned from a big Atlantic tour in his Wylo 32, Branwen, schooner-rigged with cambered panel sails.

    For the sake of science, would you Asmat be so kind and answer these two questions (apart from writing a good story for the Magazine)?

    1.      Did you during the voyages have any problems which were specifically connected to having camber in the sails?

    2.      If you were to repeat your voyage with the same boat, and knowing what you know now, would you make the new sails flat or with camber in them?

    Anyway, welcome back!

    Arne


    Last modified: 15 Aug 2018 21:07 | Anonymous member (Administrator)
    Merged topic from TECHNICAL FORUM: 15 Aug 2018 20:49
  • 17 Mar 2015 02:56
    Reply # 3254708 on 3253108
    Gary King wrote:
    Paul Thompson wrote:

    ..but LC is faster to the windward. We have not really worked out why that is but we are coming to the conclusion that it could be that LC's in sails the shape is much more controlled. ..
    Paul, I'd say it's displacement, LC can charge through the chop where Zebedee would have trouble. Badgers are light and have that heavy mast on the bow which causes hobby horsing too. 
    Gary, we are not talking about those sort of conditions but sailing in perfect conditions like we had in the Tall ships. Force 3 - 4 and flat water.
  • 16 Mar 2015 22:36
    Reply # 3254510 on 461931

    Perhaps I shouldn't have called it sail slatting.  As Arion rolls to windward, the yard and battens swing up then crash back to leeward, jarring the mast and driving me crazy.  I cannot make any progress in these conditions without motorsailing.  I had to motorsail with the bermudian rig in these conditions too but could have vanged the spars.  On Roger Taylor's latest videos, he shows his sails slatting in light airs but his yard and battens appear to stay to leeward.  Perhaps his sea-state was less vigorous than the large easterly Pacific swells I seem to get regularly.  Whatever, Ming Ming 2 is moving along very nicely and Roger sounds absolutely delighted with his sail's performance.  Ming Ming 2 is a lot lighter than Arion which must help.  Of course, in a boisterous sea with a fresh following wind, Arion is very comfortable and incredibly powerful.  As usual, it is all a compromise.  You pays your money and you makes your choice...Anyway, I am looking forward to sailing alongside Gary King on Ashiki soon and comparing notes.

    Merged topic from TECHNICAL FORUM: 15 Aug 2018 20:49
  • 16 Mar 2015 09:39
    Reply # 3253409 on 461931
    Deleted user

    Sail slatting aint an issue around here. All boats do that, including BMs. If anything its the parrel squeak that gets me. There's batten clang too, as the sewn in padding twists out of kilter rendering them useless, but I may wrap carpet all over them soon. 

    Our sails are 7.5%-6% fore-main and I'd like more. We've had lots of light windward sails in the tropics and a little more bagginess would be nice.

    Last modified: 16 Mar 2015 09:50 | Deleted user
    Merged topic from TECHNICAL FORUM: 15 Aug 2018 20:49
  • 16 Mar 2015 03:57
    Reply # 3253298 on 461931

    I'd certainly choose a much flatter sail for Arion if I did it again. I have been driven crazy by my sail slatting in light wind and sloppy swells this last year.  I'm dreaming of a big Code Zero sail.  My sail, which seems to have 8 - 10% camber, performs magnificently in light airs and flat water though.  Horses for courses...

    Last modified: 16 Mar 2015 03:58 | Anonymous member
    Merged topic from TECHNICAL FORUM: 15 Aug 2018 20:49
  • 16 Mar 2015 00:31
    Reply # 3253168 on 3252784
    Arne Kverneland wrote:

    Armchair speculations...

    Annie, take what I write below with a pinch of salt, as it is more like ‘loud thinking’:

    First of all, just about all boat types will have one or two special wind- or wave-conditions that they don’t like.

    I can see your point that it is annoying to have Fantail's sail luffing and filling as the boat rolls or climbs over big waves. Still, I wonder how a standard Raven 26 with BR does it here. My hunch is that your boat type, with her high ballast ratio and big beam, will shake the wind out of almost any rig, unless the crew sets maximum sail area to keep the boat under pressure.

    She's not really shaking the wind out of the sail - that implies quite a violent movement.  These are swells rather than waves and it seems to be to do with the apparent increase and decrease in the wind.  I'm afraid it's not very easy to describe.  I am setting the right amount of canvas, I believe and if I shake reefs out, the situation seems to get worse, if anything, probably because in an effort to reduce the flapping from happening, I sheet in harder.  But yes, I wonder how her sisters sail in those conditions.

    I wonder if Fantail simply is under-rigged. Her JR is only the same area as the working sails of the Raven 26, and there is no way she can set as much sail as the main plus Genoa1 on a standard boat.

    Actually, the sail area I put onto Fantail, is the equivalent of the main plus the No 1 genoa.  She is, in fact, a little undercanvassed in very light winds, but the situation I'm describing is in F3 and over, when she usually sails very well indeed. 

    Or maybe I am all wrong here  -  if your described situation only occurs when you already need the first reef, then I can see the point with flatter sail.

    This starts happening before I need a reef and continues as I reef down.  I usually avoid sailing in these conditions of onshore wind and swell. once the wind got over F5, so don't know if the sail would still back and fill once I had four or more reefs in.    The camber decreases in the top sheeted panel and the fanned panels are flat. 

    But on the other hand, if it is a ‘more waves than wind’ situation, then the answer is more sail, and not less camber.

    Et cetera etc, etc...

    Arne

  • 15 Mar 2015 23:36
    Reply # 3253108 on 3246820
    Deleted user
    Paul Thompson wrote:

    ..but LC is faster to the windward. We have not really worked out why that is but we are coming to the conclusion that it could be that LC's in sails the shape is much more controlled. ..
    Paul, I'd say it's displacement, LC can charge through the chop where Zebedee would have trouble. Badgers are light and have that heavy mast on the bow which causes hobby horsing too. 
    Last modified: 15 Mar 2015 23:39 | Deleted user
  • 15 Mar 2015 11:25
    Reply # 3252784 on 461931
    Anonymous member (Administrator)

    Armchair speculations...

    Annie, take what I write below with a pinch of salt, as it is more like ‘loud thinking’:

    First of all, just about all boat types will have one or two special wind- or wave-conditions that they don’t like.

    I can see your point that it is annoying to have Fantail's sail luffing and filling as the boat rolls or climbs over big waves. Still, I wonder how a standard Raven 26 with BR does it here. My hunch is that your boat type, with her high ballast ratio and big beam, will shake the wind out of almost any rig, unless the crew sets maximum sail area to keep the boat under pressure.

    I wonder if Fantail simply is under-rigged. Her JR is only the same area as the working sails of the Raven 26, and there is no way she can set as much sail as the main plus Genoa1 on a standard boat.

    Or maybe I am all wrong here  -  if your described situation only occurs when you already need the first reef, then I can see the point with flatter sail.

    But on the other hand, if it is a ‘more waves than wind’ situation, then the answer is more sail, and not less camber.

    Et cetera etc, etc...

    Arne

     

    Merged topic from TECHNICAL FORUM: 15 Aug 2018 20:49
  • 15 Mar 2015 03:21
    Reply # 3252632 on 3252606
    Gary King wrote:

    I'm wondering, what kind of keel does Zebedee have?

    It's a full-length, quite shallow keel.  As per the alternative design, I believe.
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
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