Flat, hinged or cambered?

  • 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.
  • 15 Mar 2015 02:30
    Reply # 3252606 on 461931
    Deleted user

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

    Merged topic from TECHNICAL FORUM: 15 Aug 2018 20:49
  • 15 Mar 2015 01:55
    Reply # 3252584 on 3246820
    Paul Thompson wrote:

    Arne has pretty much spelt it out. LC has 12% in her foresail and 10% in her main. She is a heavy boat and needs all the drive that she can get.
    As for Annie's Fantail, if anything, she needs more camber not less.

    I'm not quite sure why you say she needs more camber.  Usually when we sail in company, Fantail keeps up pretty well considering her lack of waterline and the fact that she won't push through the waves like "LC" .  However else you would describe Fantail, she is not a heavy boat that needs all the drive she can get.  I wrote my comment in some haste as I had other things to do that day, and was not trying to convince Chris.  But as you have chosen to pick me up on it, I will enlarge on why I said it.  Fantail is designed to displace 2.5 tons, but when I've scraped back the antifouling I can see that she has probably never floated on her marks, so would reckon she is more like 2.75.  She has 1.25 tons of lead in a low ballast keel (she draws 5ft) and is very stiff.  (Indeed, it would be hard to find a more different boat from "LC".)  The main reason that I believe that there is too much camber in the sail, is from the way it behaves when I'm sailing on anything from a close reach to just about a beam reach, offshore.  Now you may say that my sailing could hardly be described as offshore, but once one is N of the Hauraki Gulf, there is nothing at all to the E apart from South America and when we have had continuous E winds, as we have this summer, quite a ground swell settles in.  In these conditions with the wind, as I say, somewhat forward of the beam (and over about F3) there is no way I can trim the sail so that it stays full.  As Fantail rolls back up the sail luffs, as she rolls away it fills.  If I over sheet in order to eliminate this, the boat then starts complaining with weather helm and is not happy.  I feel that a flatter sail would eliminate or at least reduce the problem. Most of the time, I am not sailing in this very narrow range of wind angle and strength with a specific sea condition and it's taken me well over three thousand miles of sailing to realise that this isn't because I'm doing something wrong.


    Chris's boat is much more like mine than either of the two full-keeled boats mentioned by Paul so I felt the comment was relevant.  I have a huge amount of respect for Arne, his abilities and his sails and would never dispute his findings or denigrate the sort of sailing he does.  It could well simply be a characteristic of my boat, but sailing in these conditions becomes frustrating and stressful with the sail constantly luffing and flattening.

    Zebedee and LC sail hard against each other every time they meet (which has been a few times this summer). Zebedee is faster downwind (which is as it should be as her LWL is longer

    Don't think so Paul ;-) The 30ft Tahiti ketch has a 27ft waterline and "LC" is two feet longer.  The 34ft dory has a 38ft waterline.  You must be pretty much the same!
    Last modified: 16 Mar 2015 00:23 | Anonymous member
  • 12 Mar 2015 23:18
    Reply # 3250685 on 461931

    I've given up on making new wingsail battens. To make such a big single wingsail was too much for me to do, with limited time, with limited facilities, and above all, with limited mental energy and waning physical powers, as I approach my eighth decade. I'm going to have to leave the topic to younger men. I want to go cruising again. If I try to make a wingsail again, it will be on a smaller boat.

    I've made new straight forward battens, and these will be hinged to the after battens in the way that I'd planned with the wingsail. Then I only have to cut off the starboard side of the sail at the luff line and refinish the luff. So I'll have put the clock back to the days before we all started playing with cambered panels. We didn't know how to make hinges with a large angle of articulation then. We do, now. My hinges will have an angle of articulation of 20 degrees each way, resulting in a camber of 8.5%.

    Ideally, I would add a small amount of camber to the part of the sail that is forward of the hinge, so as to get good curvature forward, while keeping the after part of the sail dead flat. Which is the way I prefer it; it's so much nicer to live with a flat sail. A flat sail doesn't go well to windward, so we need camber. Put that camber in the forward part of the sail, and we have the best of both worlds.


    Merged topic from TECHNICAL FORUM: 15 Aug 2018 20:49
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