Sail Balance - Position Relative to Mast

  • 10 Sep 2017 02:23
    Reply # 5072571 on 4793670
    I'm starting to think that anyone who wants a junk-rigged boat might be better off converting than buying a professionally-built junk!!  It's all very interesting, though.  Now I wonder what the story is on the Kingfisher 20+ with junk rig.  Comments anyone?
  • 09 Sep 2017 20:39
    Reply # 5072225 on 4793670

    Slieve McGalliard wrote:

    As with the Coromandel, I have just run the measuring stick over the few rough Kingfisher 26 drawings I could find and again seem to find that the junk rigged version has heavy weather helm built into the design. Are we to assume that those who planned these rigs had no regard or understanding of rig balance, and probably worse, that those who have been sailing them have not questioned the balance and performance?

    If this is the case, are we going to find that a lot of the other older professionally rigged junks are also suffering from the same malaise?

    I just hope that I've made a mistake somewhere, and that this is not the case.

    Peter Scandling sailed with me today, and I found that 

    1. The K26 Tara's battens are very small in diameter, and probably date from the time that Sunbird was using its customers as guinea pigs to see if flexible battens worked. They didn't. What happens is that they bend into a semicircle that puts the draught much too far aft. This will markedly increase the weather helm and drag the boat sideways, not forwards.
    2. The sail is not the original, so when Clay Everington made an Atlantic circuit in this boat, she may well have had battens of a suitable size, and this "experiment"  may have happened later on.
    3. The mast does not fill Peter with confidence. It is far too flexible, and he thinks it unfit to go offshore. He talks of replacing it with a tapered pole from ALC, similar to mine and probably a size or two larger.
    4. In which case, it makes sense to go for a higher AR sail, which will push the centre of sail area further forward, decreasing weather helm and increasing performance.
    5. As well as rig troubles, the rudder is very stiff, as well as ineffective. A good case can be made for a transom hung rudder to a better design.
  • 08 Sep 2017 23:41
    Reply # 5071228 on 4793670

    Yes, Arne, there seem to be many junk sailors who enjoy their boat with the easy to handle rig and just accept that the performance is poor. What is annoying is that many pay good money to have them 'improved' with added hinges and re-rigged without batten parrels and still have poor performance. Having the rigs flying around only held on by the luff hauling parrels is positive dangerous in my opinion, and I know of some who have been in real trouble in a seaway because of the 'slack' rigs.

    I wouldn't be surprised if a lot of boats are sailing around with excessive weather helm, as many seem to sail under canvassed or with cut down rigs. Poor performance seems to acceptable, for some reason. No wonder the pointy heads have a low opinion of the junk rig.

    The ridiculous thing is that many Amateur designed rigs are still providing the same easy sailing, but also giving a respectable performance. In some respects it is embarrassing to sail rings round another junk rigged boat, but it does show what can be done.

    David, I think you have miss-understood my reference to a custom rig. I said that I had run a few measurements on the Coromandel and that it should be easy to produce a tailor made split rig for that boat. To be more precise, the mast position on the Coromandel is too far aft for the original rig and is just about spot on for the split rig. I believe Amiina's original rig on Emmelène just needs a small adjustment, and one drawn with a better aspect ratio would be ideal. (But as I say, I'm biased).

    Cheers, Slieve.

  • 08 Sep 2017 10:39
    Reply # 5069988 on 5069851
    Anonymous member (Administrator)
    David Tyler wrote:

    What puzzles me is there must be plenty of JR Newbridge Pioneers and Kingfisher 26s sailing around, apparently without cause for complaint. Surely they can't all be accepting excessive weather helm? 

     Good question, David. I fear that the owners of these boats have not been spoilt with high performance of their boats, after 20 -30 years with flat ('hi-power') sails. Even the fitting of H-M sails with hinged battens must have felt like an improvement?


  • 08 Sep 2017 08:38
    Reply # 5069851 on 4793670

    As it happens, I've just been hearing about two boats with severe weather helm problems: KRKA, Lynda and David Chidell, and Tara, Peter Scandling.

    Yesterday, I sailed alongside KRKA, briefly - or more accurately, sailed rings around her (in spite of  having to drag my outboard through the water). The sail is HM, with hinged battens. The hinges are in similar position to those in Weaverbird's sail. The only thing I could see that needs improvement is that there are no batten parrels, but only two LHPs, to position the luff. This was allowing the luff to blow far away from the mast, when the mast was to windward. I suspect that adding batten parrels will be a great improvement, but whether it will cure the weather helm, I don't know.

    Peter is coming to sail aboard Weaverbird on Saturday, to see if he can learn anything from her rig. I can say (smugly) that the helm balance is perfect, when sailing to windward, however many reefs are in. I have no idea, though, how much of this is due to the form of the hull, keels and rudder, and how much is due to the planform, camber and position of the rig. 

    What puzzles me is there must be plenty of JR Newbridge Pioneers and Kingfisher 26s sailing around, apparently without cause for complaint. Surely they can't all be accepting excessive weather helm? 

    Slieve, you mention the possibility of a custom design of split rig, where the mast has simply been placed too far aft for whatever reason. Where the balance would fall, as is likely, within the range 15 - 25%, I would agree that this would be a good way of moving the rig's CE forward (although I accept that La Chica does very well without the split - probably due to the deep camber, as I think that it's the flat and mildly cambered sails that suffer most from having a lot of balance).

    Last modified: 08 Sep 2017 17:19 | Anonymous member
  • 07 Sep 2017 11:34
    Reply # 5067100 on 4793670
    Anonymous member (Administrator)

    David Tyler wrote:

    «IMHO, sails with a lot of balance area are very good for going downwind, but not much use for anything else (I exclude split junk sails from this sweeping statement, as they are playing by a different set of rules). When the mast is to leeward, we need to get it into the separation bubble which lies quite close to the luff.»

    I too feared that a big (mast) balance in a cambered panel sail would lead to bad performance on the mast-to-leeward tack, so I kept the balance between 8 and 12% in my sails. However, Paul Thompson has clearly demonstrated that 18 -22% can be used, and his La Chica still performs well on both tacks. After the first couple of trial sails of the new JR on my IF, Ingeborg, I shifted the sail forward from 10-11% to 14-15% balance, and it works fine. Only fine instruments would tell if, or how much performance I lost. My hunch is that I gained more than I lost as the change improved the helm’s balance. Nevertheless, this myth of the bad tack is not easy to bust.

    David also wrote:

    «The Hasler planform puts the area of the upper panels further aft than sails with a lower angle of yard, and this will contribute to weather helm; getting worse the more you reef. This, along with the longer luff, is a major part of my thinking in Weaverbird's sail.»

    I have never had a problem with this. I am on my sixth JR with some sort of H-M planform. They all reef beautifully. If anything, any weather helm is a bit reduced as I reef (not much). It may well be that the top section of my rig sits further aft  -  I haven’t checked  -  but it is no problem. Maybe this is the reason why I don’t end up with a bad lee helm when reefing: It is easy to forget the windage of that (bare) mast.

    Nowadays there is little reason for building the sail with a Johanna-style planform to minimise balance at the mast. When I still build them this way, it is mainly for three other reasons:

    ·         The boats I have converted has more or less forced the masts to sit well forward, because of the deck or interior layout. This again forces me to fit the sail with moderate balance to avoid lee helm. A tall yard angle (70°) is a natural result of this.

    ·         The high-peaked Johanna-style sail lets one set the biggest and tallest sail on a given mast length. Remember; one can always reef that sail, but one cannot reef the mast.

    ·        I have found the 2-3-panel top section to be a very efficient hard-weather sail, downwind as well as upwind. If properly rigged and with the FUP (fan-up preventer) set, it should be as trouble-free in use as any (still only 5 running lines).



    Last modified: 07 Sep 2017 15:55 | Anonymous member (Administrator)
  • 07 Sep 2017 08:55
    Reply # 5066986 on 5066305
    Slieve McGalliard wrote:OK. I'll admit I'm biased.
    Amd why not?  It seems like an elegant solution to the issue of weather helm!
  • 07 Sep 2017 04:28
    Reply # 5066747 on 5065720
    David Tyler wrote:

    IMHO, sails with a lot of balance area are very good for going downwind, but not much use for anything else (I exclude split junk sails from this sweeping statement, as they are playing by a different set of rules). When the mast is to leeward, we need to get it into the separation bubble which lies quite close to the luff. When the mast is to windward that doesn't apply, though. My feeling, without much evidence to back it up, is that you probably have a similar situation to that of Jilly, the Vertue that wouldn't tack and sailed very poorly, until Gp Capt Smith replaced the HM sail with one of his Fenix-style sails: high AR, not much balance area. He got some camber from the fanned shape, but that didn't make it a  very good cruising sail, as the batten stagger when deeply reefed was extreme, so I wouldn't go this route.

    David, LC has rather more balance than most in both of her sails and I cannot say it hurts her windward performance at all. I did wonder when I first tried it but in practice I cannot say that it's a problem. Any one in NZ who has sailed with me knows that LC goes to the windward rather well... What I'm getting at is it's more a theoretical disadvantage than a real one.
  • 06 Sep 2017 21:03
    Reply # 5066305 on 4793670

    Hi Richard,

    The model yachts in the video are 'Bottle Boats' and are made of two 2 litre soft drink bottles with a carbon collar in the middle which includes the keel, mast support and radio bits. The rudder is pop-riveted to the end cap and the bow is a plastic drinking cup. The whole thing is held together with electrical insulating tape. The sails are made of bin liners, but, and here is the key to the success of the class, the rigs are Roger Stollery's balanced rig, with 33% balance. Roger built one for me which I raced for a season. Great fun. The big point was that the rig is not sheeted by a winch but uses a single 9 gram servo which has very little power, yet will take the rig from squared off to close-hauled in less than one second. Put multiple battens (booms) into it and you have a Split Junk Rig. In the video they are using small rigs as the wind is quite strong, but there is a mast extension which carries the big rig, as seen on one boat, and it does make an elegant boat and gives very close and exciting racing.

    Having run a few dimensions on a drawing of the Coromandel and a Bermudan Corribee I can see that the Coromandel will have weather helm problems. I must get in contact with Chris Boxer as having looked at the rigs I believe his split rig on would benefit from a small adjustment to the jibs. It would be easy to draw up a tailor made Split Rig which would be ideal for the Coromandel with its present mast position. OK. I'll admit I'm biased.

    Cheers, Slieve.

  • 06 Sep 2017 16:34
    Reply # 5065890 on 5065720
    David Tyler wrote:I wouldn't make another flat sail, and I wouldn't add more area, making for a lower AR.
    Fear not, if I'm making a new sail it will definitely have camber somehow. But I also suffer from poor downwind performance in light airs — a problem for cruising — so I probably will add more area. It's very likely that my next sail will be made of polytarp and duct tape so I can be sure of the balance before I start serious sewing.

    The exact details of my boat are probably best kept in another thread, such as “New Sails for Tammy Norie”. I'm just keen to extract relevant experience here, for the benefit of all.

    I agree that the split rigs and aero junks are playing by different rules, and with Arne's earlier statement that they're more like two sails. Slieve's reference to model yachts is fascinating.

    Speaking of which, look at these go!

       " ...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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