Flat, hinged or cambered?

  • 12 Mar 2015 21:55
    Reply # 3250595 on 3247321
    Asmat Khan wrote:

    Hi Arne,

    You are quite right: excessive heel can easily be reefed away. All the same, David Tyler has sailed under a variety of rigs and varying depths of camber, and has given his opinion that less is desirable in an offshore cruising boat. I lack his breadth of experience, so am reduced to dumbly following his advice. Perhaps he will come in and state his reasons for this belief.

    The reason I say this is not to do with making good speed to windward. Or rather, it is to do with the lack of necessity to make good speed to windward, when well offshore. Other things become more important. I dislike the way the after part of a well-cambered panel will empty, then fill with a bang, in a sloppy sea, for example. 

    In my fantail sail, I only put 6% camber into the lower panels. Yet I made the trip from NZ up to Alaska, which involves many windward miles, and is a trip that bermudan boats don't care to do very often. I had absolutely no difficulty, and never felt I was lacking in windward ability. 

    But if I had entered Tystie alongside La Chica and Zebedee in the Russell Tall Ships race, she would have been struggling to stay with them. Inshore, and when racing, throw in all the camber you want. Offshore, I'll stick to my belief that it's better to stay at the middle of the spectrum - not too flat, not too full. Moderation in all things.

    Certainly Zebedee has sailed offshore with his cambered sails. La Chica has not, yet. Anthony Swanston, Wild Fox, and Paul Fay, Ti Gitu, both had trouble in getting cambered sails tame enough for relaxed offshore sailing.

  • 11 Mar 2015 20:48
    Reply # 3247807 on 461931
    Anonymous member (Administrator)

    Good, Asmat

    I bet the rise in performance when going from flat sail to 6% camber is bigger than ‘the next jump’ would be  -  from 6% camber to 8 or 10% camber. I think the 2-sail junk will perform better than a 4-5sail gaff cutter or ketch will do.

    You mention Hong Kong parrels. They have nothing to do with batten stagger when the sail is being reefed, only with the set of each panel when hoisted. The parrels you plan to use  -  maybe combined with Slieve’s very clever combined battenparrel/downhaul will probably make the Hong Kong parrels redundant.




    Merged topic from TECHNICAL FORUM: 15 Aug 2018 20:49
  • 11 Mar 2015 17:32
    Reply # 3247321 on 461931

    Hi Arne,

    You are quite right: excessive heel can easily be reefed away. All the same, David Tyler has sailed under a variety of rigs and varying depths of camber, and has given his opinion that less is desirable in an offshore cruising boat. I lack his breadth of experience, so am reduced to dumbly following his advice. Perhaps he will come in and state his reasons for this belief.

    With 6% camber, I do not expect to be exempt from the curse of positive batten stagger, although I am hoping to be able to do away with Hong Kong parrels. I plan to achieve this by use of the yard hauling and throat hauling parrels, perhaps with a Columbie egg thrown into the mix: (the combined downhaul/batten parrels Slieve is using in Poppy).

    My Branwen is a Wylo 32, steel hulled gaff cutter designed by Nick Skeates. If you don't know the design, think Land Rover, not Jaguar. 9.7m LOA, 8.5m LWL. Designed displacement is 6.25t, although mine is rather overweight and probably displaces 8.5t in cruising trim. My junk sails will have the same area as her present rig, 61.5 sq m with everything set - main, staysail, jib, main topsail and jib topsail. Without the party frocks, she is badly under canvassed below F4. 

    Cheers, Asmat

    PS My sails were designed by you, based on the master sail drawings in your excellent   Public Domain files.Thank you.

    Last modified: 11 Mar 2015 17:35 | Anonymous member
    Merged topic from TECHNICAL FORUM: 15 Aug 2018 20:49
  • 11 Mar 2015 11:56
    Reply # 3247071 on 461931
    Anonymous member (Administrator)


    I can see the point in keeping your boat reasonably upright, but remember two things:

    • 1.      The photos you have seen of La Chica have most probably been taken when she was racing. Who worries about the cook’s wellbeing while racing?

    • 2.      The point with using sufficient camber is to avoid being underpowered when the wind drops to F4 and below. This means you will be sailing more and motoring less. You may still decide for a maximum heel of, say 20°, but that can easily be achieved by reefing.


    PS: What it the displacement and length of your boat


    Merged topic from TECHNICAL FORUM: 15 Aug 2018 20:49
  • 11 Mar 2015 10:23
    Reply # 3247022 on 461931

    I have briefly owned a junk rigged Tahitiana, (Irena), that had circumnavigated under her flat sails designed by the late Jock McLeod. She was a fine sea boat: very stiff, I never came near to putting her rail under, but woefully lacking in power to windward. Had she not succumbed to rust, I would certainly have given her a cambered rig.

    Looking at photos of La Chica and other boats that have been given deeply cambered sails, it is striking that they seem to sail fast, at angles of heel that would bring forth dark mutterings from my cook. My Branwen is a shoal draught centreboarder, admirably stiff, but I still feel that 6% might be as much camber as she wants. I am not interested in making speed to windward; all I ask is that she will tack confidently and bring us home safely and in comfort.

    Cheers, Asmat

    Merged topic from TECHNICAL FORUM: 15 Aug 2018 20:49
  • 11 Mar 2015 00:50
    Reply # 3246820 on 461931

    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. I don't think she has to much camber at all. Indeed I suspect that I could go to 14% in the foresail but unless I could somehow increase the separation between the two sails, 10% is as much as the main can handle (foresail back winds the main).

    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 and she is lighter) 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. She has a carefully profiled entry that gives the desired 8 deg entry angle and by using the shelf foot method of construction the sail shape is more controlled. Also her sails are built using traditional sail making techniques and so distort less than those built using Arne's simple methods. That is not to degenerate Arne's methods which are great (I use method 'B' to join the panels and create the batten pockets) but they are lightly built and there is a price to pay. Of cause there is a price to pay when you build sails my way as well... that is time. Instead of just taking a week or so, LC's sails took three weeks of 8 hour days.

    As for Annie's Fantail, if anything, she needs more camber not less.

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  • 10 Mar 2015 17:46
    Reply # 3246490 on 461931

    I must confess I am blown this way and that by all the conflicting advice on camber that has appeared here. Little wonder that I have timidly chosen a moderate approach for my Wylo, in which I hope to venture far offshore. I am almost persuaded by Kurt Ulmer's argument in favour of flat sails, but had 8% camber on my last conversion, a kingfisher 26 and was very pleased with her performance, which was equal to that under her old Bermudan rig.

    It was David Tyler who suggested here a while back, that 6% would be the right depth of camber for an offshore cruiser. He has sailed more miles than most of us, so I listen carefully to his views. I also find your argument in favour of more depth of camber convincing, Arne; if you go to the trouble of putting camber in your sails, you may as well go all the way and have as much camber as is necessary for a heavy boat.

    I hope to be stepping masts next month, so we shall see how things turn out this season.

    Cheers, Asmat

    Merged topic from TECHNICAL FORUM: 15 Aug 2018 20:49
  • 10 Mar 2015 14:51
    Reply # 3246232 on 461931
    Anonymous member (Administrator)

    here we go again...

    During all those years since I introduced 10% camber to Malena’s sail in 1991 (hinges) and later gave her 8% camber with baggy panels (1994), these numbers seems to have been regarded as over the top, somehow. One strong argument has been that I don’t sail offshore with it, so I cannot know what I am talking about  -  my boats are ‘Fjord Flyers’  -  end of discussion.

    Well, here is my answer:

    • 1.      With the generous rigs that I give my boats, we will be down on 3 – 4 panels in F5+ conditions. In that case, the dominating part of the sail will be the three top panels, which have been cut with much less camber. What more harm can these baggy, but reefed-away panels do offshore than inshore? And yes, strong winds may blow along the fjords as well, and since the chop there is lower than offshore swell, I may even hang on to sailing in stronger winds than I would do offshore. I have actually sailed enough offshore to know that we tend to reef a lot more conservatively there than in wave-protected waters.

    • 2.      Ok, then, let’s say that I am a fair-weather sailor and know nothing about what it takes to sail offshore. What then about Alan’s Zebedee  and Paul’s La Chica? Both their new sets of sail have been given real camber, around 10% +/-. Both Alan and Paul appear to thrive immensely well with their new rigs. Are they too in the camber extremist class now, and do you expect that they will soon come to their senses?

    • 3.      I have a couple of books about ordinary sailmaking, and I have made a few of those sails as well. Nowhere in those books is there any warning of any kind against cutting  proper camber in offshore sails. Only the storm jib and trysail is cut flat. Why then should we make a special offshore rule for junk sails and not for gaff sails or Bermuda sails? Is it just ‘felt that’?

    I don’t buy all this common sense. Instead of deciding for an amount of camber, depending of inshore or offshore sailing, I let the total displacement and displacement/length of the vessel be the dominating factors. If the vessel is in the Colin Archer league, I would go for maximum achievable camber in the lower panels, say 10 -12%. On medium light and trim boats I would start with piling on a fairly big sail for good downwind performance. Then I would cut the camber in the lower panels to about 8 %. This, less powerful sail will let me carry almost as much sail area when close-hauled as when running. On a really trim flyer, say a Skerry Cruiser or sharpie (or even a trimaran), I may reduce the camber to 4-6%, mainly to make use of these boats’ characters and go fast to windward, both speed-wise and VMG-wise.


    PS: Eight percent camber (= 1/12.5) is actually moderate or ‘middle of the road’ camber, according to the books. The resulting bagginess in junksails may look extreme, but it is not what we see that counts: It is what the incoming air molecules see...


    Last modified: 11 Mar 2015 09:23 | Anonymous member (Administrator)
    Merged topic from TECHNICAL FORUM: 15 Aug 2018 20:49
  • 10 Mar 2015 11:45
    Reply # 3246111 on 461931

    Annie, you say you'd prefer less camber; how much does Fantail's sail have? This is purely of academic interest, since I'm just finishing Branwen's sails: 6% in the lower panels, reducing to virtually flat at the top.

    Merged topic from TECHNICAL FORUM: 15 Aug 2018 20:49
  • 26 Mar 2011 05:01
    Reply # 553507 on 545453
    Ketil Greve wrote:

    Hi Graham,

    I have been sailing Edmond Dantes a few seasons now, having reefed and shaken out reefs, dropping and hoisting sails a few times. I can assure you that the battens land just how they please, but I have never had any problems with snagging at the rear end of the sail. Any problems occuring is at the other end, but are easily sorted, but I have to move to the mast to sort snags with parrels/ Hong Kong parrels. Hong Kong parrels sometime gets trapped under the next batten and has to be freed. I have thrown away the luffhauling parrel as it dit not do any significant differece. I have a shock cort tied to the boom to stretch the luff, and ties the battens as I reef to have a taut luff, (good for performace). I find the rig much simpler and easier to use than anticipated after reading all the hot air theory in the various foras discussing this wonderfully simple and efficient rig with the unfortunate name Junk Rig.


    Ketil Greve

    Thanks Ketil, I just saw your comment.  I hope that I will soon be discovering a few things first hand as I hope to be sailing with my junk rig by the end of May.  I ended up with an HM type sail modified by David Tyler, with 4% camber and a yard topped up to 70 degrees and a bit shorter than the battens.  I am sure I will make a lot of mistakes at first but with the help of JRA members and the rig's ease of adjustment and refinement, should eventually get it sorted out.  Then its back into cruising mode!  I'm living on a contruction site at the moment!
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

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