Junk rig on modern hulls

Discussion in 'Sailboats' started by BATAAN, Sep 2, 2011.

  1. MastMonkey
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    MastMonkey Junior Member

    I guess I am one that doesn't like to compromise. My interest in the junk is principally its ease of handling characteristics. As a disabled sailor, a bermudan rigged boat is nearly unmanageable. I like to be able to everything on my boat. And I can manage the sails, but it was expensive to get them as such and the solution is still unsatisfactory. I am also a daysailor though with plans to cruise during the elusive "one day". I like sailing close hauled. And I like not using my engine. I am not a racer or have much interest in racing, so I am not motivated by such concerns, but, I also feel like there is still much room for modernization and innovation of the rig as is often discussed.

    Some of the thread has already addressed some modern enhancements of the rig: cambered panels. Personally, I think they make sense as the fabric will stretch anyway. You might as well attempt to control it. And there is quite a bit of room to experiment with composite materials.

    Principally, in addition to the question of sails I was also hoping to see some discussion of considerations of hull design that would be complimentary to a junk rigged boat, if there are any.

    What is it that is the principal disadvantage of the Junk sail? Is it the weight aloft, meaning sail area must be spread out on additional mast creating drag? Has it been the lack of camber in the sails? Or is it related to the usually aspect ratios of the sails? It would be nice to quantify some of these and I know the JRA is attempting too. There are just too few boats to make comparisons. The did do a comparison between identical models of a boat, one with the original marconi rig and the other converted to a junk rig. It was actually a narrow weather window in which the bermudan bested the junk rig. I will have to try and find details again.

    Thank you all for your detailed answers.
     
  2. pdwiley
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    pdwiley Senior Member

    Compromise *what* ????? You haven't said. What do you want the boat/rig to do? What is essential? What is desirable? What is nice? What is irrelevant?

    Every boat is a compromise.

    PDW
     
  3. pdwiley
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    pdwiley Senior Member

    Which owner? Can you give the URL for this posting?

    It just occurred to me that you might be talking about the current owner, whoever that might be, not the original owner.

    PDW
     
  4. pdwiley
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    pdwiley Senior Member

    Hey Bataan, how is your main sheeting and sheetlets set up? Are you using double sheeting or single?

    PDW
     
  5. BATAAN
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    BATAAN Senior Member

    BERTIE has a "Big Eye Chicken" mainsheet, which is single, but at sea we rig vangs to the upper two battens exactly like they do. These can be used to take twist out and also to stop the upper part of the sail from slamming about in a seaway. Had Colvin style double sheets when I first rigged the boat, hated them. Lots more bits of wood to hit you in the head, slow to adjust, more to go wrong, little bit better shape to sail. Our sheet deadends at the second batten from top and is 5:1, two spans, all Harken and Schaeffer blocks.
     

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  6. MastMonkey
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    MastMonkey Junior Member

    All I meant by that comment was that often I feel we let preconceptions keep us from exploring and developing improvements. We assume a junk rig has certain characteristics and limitations and never try to overcome them. We accept it for what it is. Compromise is understandable, and as you point out necessary on a boat. But, the history of sailing too is full of examples of preconceptions becoming prevalent that with the drive for improvement are proven to be false. How many people used to believe a multihull can not point? At least I hear that from other sailors at my marina. And of course it isn't true.

    There is no boat. My question are purely academic. I would like to develop an understanding of the problem beyond the opinion and hyperbole that is prevalent online. At least there is the JRA.
    What I would want the rig to ideally do is perform comparably to my bermudan rigged boat in general conditions so that I could more easily single hand it. In my previous post I mentioned that I had made several modification to my boat to accommodate me. And still I do not find these satisfactory. But my boat performs well and I can almost always find crew so it isn't my biggest concern. It would be nice though to simplify the setup so that handling is greatly improved and not too much in performance is given away. Of course I would accept it if some must be sacrificed.

    Yes. It probably is not the original owner.

    URL: http://www.sailnet.com/forums/boat-review-purchase-forum/7574-colvin-gazelle.html

    That is the first I have found. Additional searching could find more.

    Did you experiment with any other sheeting setups to develop anti-twist. How did you settle on the setup you have. I agree with you one the double sheeting setup. The few times I have seen it, I felt it looked terribly inefficient. Not very much is gained for the additional amount of hardware. Plus I think it looks hideous from an aesthetic standpoint.

    Do you think modern hulls have enough buoyancy to properly support the weight of a junk rig well forward as in the videos? What part of the junk sail creates the most weight aloft? The battens and blocks?
     
  7. BATAAN
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    BATAAN Senior Member

    We started out with many of Colvin's details in rigging, but I've changed most of them. BERTIE's sheet setup is close to traditional because I've found it works best of the various leads I've tried. Remember, this is not a Hasler or Colvin designed for a light displacement yacht, but a Swatow cargo ship rig designed for brute horsepower and fairly standard in its height/breadth/yard angle/# of battens so they figured out what did the job through long use, and I simplified that by turning their sheet upside down and making the hauling part the lowest. This makes one less high-up leech rope flailing about and trying to catch the radar and mizzen mast head and by using low friction blocks the result is the much the same, just 5:1 instead of 6:1. As initially tried out, putting a block aloft and the upper section the hauling part it gave slightly (!) less twist, but I settled on the present simple sheet years ago and would not change it. My boat is an exercise in development and many things have been tuned up and improved in the 26 years we've been actively sailing her, much of it at sea in bad conditions. Another thing that makes my rig heavy is the great strain a Swatow type puts on the halyard and masthead, so the the masthead detail includes quite a bit of steel in the crane and cap, plus 1/2" steel shrouds and forestay plus lighter jibstay.
    At the recent Wooden Boat festival we had hundreds of people aboard at the dock and then went sailing with somewhat fewer and many remarked how simple and smoothly everything worked. The headsail sheets are single part and on Spinlock rope clutches. When tacking I can usually pull both across at once and if I time it right never have to use the sheet winch.
    On a more modern hull I would think a taller narrower lightweight sail of more Hasler-like dimensions on a high-tech (birds mouth spruce, aluminum, carbon fiber or?) free-standing mast would work, as it has on others of the type. BERTIE's stability would throw an unstayed mast into the next county and her heavy rig keeps it all under control no matter what happens.
    A cat ketch or schooner rig can tend to depress the bow in some conditions and can overpower a too-small rudder possibly causing a broach, so for ocean sailing a hull with strong directional stability is a plus. I helped some friends rig a Chinese unstayed cat schooner (identical sails) on a 36' steel lifeboat hull 40 years ago and it worked great. BADGER is a great example of a simple adaptation using modern Hasler-like details. A hull with short or fin keel and separate rudder takes a lot of thought to change to Chinese rig successfully. Junks have huge rudders, often lowered deep below the keel.
    Longer battens bend too much when the wind pipes up so are made stouter and heavier etc. A tall narrow sail has shorter battens so they can be lighter. Also its head is a different shape and has a much shorter yard in relation to sail area. BERTIE's yard is 22' long and 4x6 at the center and solid doug fir, so is quite heavy. For battens I recommend Colvin's details and 6061t6 aluminum tubing and carry a few 3' pieces of the next size larger for repair sleeves (BERTIE has two repaired battens like this). When the batten fails and folds like a soda straw, get 6 or 8 seizings off in each direction from the break, get a piece of wood between the cloth and pipe and finish breaking, then pound the ends round. Take your repair sleeve and slide it on one of the broken ends until it's past the break, align the ends, slide the repair sleeve so its middle is over the break, then renew the seizings you removed. No need to touch the ends of the batten or remove much at all and takes less than an hour for a permanent repair.
    The rig seen on catamarans which is a marconi with full length battens and extreme roach but no yard is a logical step in the idea. Large sail area for mast height due to roach, battens allow lighter cloth and simple reefing and excellent shape for windward performance.
     
  8. pdwiley
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    pdwiley Senior Member

    Interesting. Thanks. I'm going to rig mine as per the designer's plans in the first instance. If usage shows things I don't like then I'll change it. Tom's logic seems sound to me and it obviously works for him.

    The rigs are quite different of course.

    He doesn't like the Hasler type rig (though it obviously works).

    Some of his comments on why his rig is designed as it is:

    "The centers of effort of the panels as I design them is the same as used in China on the junks I sailed on. The individual a fair curve which plots out as a lazy S. The upper panels CE's are forward of the total CE. Not having a large Chinese crew to throw the sheetlets past the leech I use double sheeting and sheetlets to a euphroe which is occasionally seen in China. Thus in tacking I do not need to do anything except put the helm over. If it is a junk rigged schooner then I do have to tack the jib and trim it for the new tack."

    What do you use to raise your mainsail? With that much area it has to be seriously heavy.

    One thing you never (rarely?) see is a junk ketch rig. Wonder why...

    PDW
     
  9. pdwiley
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    pdwiley Senior Member

    It's worth getting Tom's books because he has done a bit of experimenting using different rigs on the same hull form. You need to be careful not to generalise from those to all hull forms of course but there is some data available.

    He does comment that the junk rig is second only to a square rig in terms of the number of bits of string so whether this is an issue for someone with a physical disability would need to be considered.

    My question re compromise was aimed at getting you to state what you were trying to achieve, no more. If, for example, you insist on maximising the ability to sail close to the wind then a junk rig isn't going to work for you.

    My criteria only list maximising upwind ability as a desirable attribute. Ability on other points of sail, minimal or no sail changing while underway, fast reefing, ease of single-handing and ability to build the entire rig myself rate more highly. Also keeping within a budget of $10,000 for rig & sails.

    On the sailnet post, the poster referring to MIGRANT was the 2nd or later owner. The original owner had the boat for 30+ years and sailed her all over the Pacific basin, as far south as Tasmania where I live. I used to know his slip neighbour on a different forum. I don't know how much the sailnet poster knew about sailing MIGRANT but he (or someone else) put her up for sale back in 2004 or 2005 I think as I saw her advertised around then in Malaysia. I thought seriously about buying her but it all got a bit complicated. One or more of the owners after the Johnsons added insulation to the hull and trapped water where it couldn't be seen. Some re-plating had been done by welding patches on the outside, over the original plate. I didn't like that.

    Anyway I don't think I'd take a great deal of notice of his comments re pointing ability. 170 deg AND leeway means the hull makes no distance good to weather. Seems very unlikely unless something is very, very wrong with the rig, the trim or the person sailing.

    PDW
     
  10. BATAAN
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    BATAAN Senior Member

    BERTIE's halyard leads to a ww2 landing craft bow door winch (Beebe Bros Seattle 2 1/2 ton) with 1/2" Sta-Set X line. This is a cheap low stretch yacht braid which lasts a good long time. The line gets thoroughly greased with vaseline where it sits in the block aloft when the sail is hoisted. The winch has two speeds and a very good brake.
    Being single part with a direct reversal, the halyard load on the single block aloft is very high. Starting with an America's Cup titanium backstay block we have destroyed a long line of ever-more-costly blocks culminating in a $400 Harken which again rained plastic bearing balls and the sail crashing down in the lifts at 2 am at sea. Finally found the right one, made for logging, solid steel with industrial ball bearings, a 5/8" hardened bolt for a shaft and says "5 ton capacity, made in China" on it.
    Winch is mounted on a steel fabrication made of large diameter pipe with 3 bolts through deck and beams from a wide steel plate at the bottom and another plate at the right height and angle to make the winch easy (!) to crank. No coils to foul in the dark and fewer blocks/ropes aloft. Positioning of this is important as the halyard must lead down the "chimney" at the right place to avoid chafe.
    One thing about Chinese, as soon as one panel is up, you are sailing in control with a greatly reefed sail and can take a break, go down below and brew some coffee. Drink it, have a cookie, come back up and crank some more.
    In a western sail without battens, it is either up or down and everything in between is confusion.
    Harken self-tailer on mast is to tension luff parrals and lift small boat.
     

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  11. pdwiley
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    pdwiley Senior Member

    Hmm, interesting, thanks. I've got a 500kg bomb winch that stores its own cable and self-locks, not sure how much cable it holds though as I inherited it. Looks like a planetary gearbox. Might have to take a closer look next time I'm at my Sydney house. Otherwise I'll probably build something though my sail weight is going to be nothing like yours so the need is dubious. Total sail area is 720 sq ft I think Tom said, for the 3 lowers. I've got some nice bronze worm wheels to use as a basis for winches, nice thing about high ratio worms is the worm can drive the wheel but the wheel can't drive the worm so self-locking and bi-directional. Industrial sprag clutches are another neat gadget but uni-directional.

    WRT blocks I'm not surprised. I *never* buy yacht fittings if I can help it. I spent a lot of my working life on oceanographic research vessels of one type or another, I buy fishing or industrial stuff. If it doesn't have a stated SWL then it doesn't have one and I go out of my way to avoid it. I can buy a 10mm galvanised shackle with a 1 tonne SWL for approx $3.00 or a stainless one with no stated SWL for 3-4X that price. Alternatively I make stuff myself but I have a pretty comprehensive machine shop so it's not an option open to everyone I realise.

    I like your boat, BTW. I've thought of building something heavy displacement and if I get tired of the one I'm building now I'll build a heavier one. Can't go much over 12m because the shed isn't long enough (unless I remove the mezzanine floor anyway) but I can go to 3.9m beam and still get the hull out the doors.

    PDW
     
  12. BATAAN
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    BATAAN Senior Member

    Whatever arrangement you have for a halyard, the most important thing is that the sail come down in a few seconds, at any time, without question. A 3 fold purchase is usually enough on sails under 400 sq ft. Winch only necessary for very large heavy sails and use rope, not wire, so can be cut with knife in emergency. BERTIE has no turnbuckles for same reason (and others).
     
  13. Petros
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    Petros Senior Member

    I have messed with small junk rigs and find them great for simple handling. Also the stresses are much lower than in conventional rigs so everything can be lighter. Their disadvancage is they will not point as high into the wind, but I am working on a way to solve this problem.

    I want to modify the junk with flexible battens, and two surfaces with the mast in between them, forming a foil with some thickness, that sail surfaces attached at leading and trailing edge. And than a rotating mast and sheetlet arrangement that allows for adjusting both the angle of attack of the LE of the sail, and the camber. This will allow for controlling both the camber and the twist of the sail along its whole length. I think this will greatly improve the performance of the design over conventional sails.

    Hopefully the design will not be too heavy when scaled up for full sized cruising or racing sailboats. But I am not done working out the design problems on a 14 to 16 foot long hull first.
     
  14. Tad
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    Tad Boat Designer

    Petros.....

    Sounds like Jack Manners-Spencer's Gallant Rig, also called the Aero-Junk.....
     

  15. MastMonkey
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    MastMonkey Junior Member

    I have often thought that the higher aspect sails split onto separate mast, made sense for a junk rig for some of the reasons you have given as well as the easier sail handling. I wonder though if the improved performance on aspect sails is enough to offset the additional drag of an additional mast. This relates closely to my initial question about using western sails in combination with the Chinese rig. Weight wise I have not read much about composites being used in the creation of junk rigs, but I think they would pair satisfactorily with composite freestanding masts. Is your mast stayed due to the size of your mainsail? Are stays typical on swatow type junks?

    I have heard the junk rigged disparaged for its apparent complexity, but I think it actually compares favorably to bermudan rigs. My own boat which I have modified for sail tuning and easier sail handling is a comparable mess of lines between its reefing systems, rig tuning, and additional sail handling lines. And as you pointed out earlier in the thread the numerous metal bits that keep it all upright. But, it still doesn't quite have the ease of use I was desiring. I would gladly sacrifice the ability to work upwind for the safety and ease of use I think a junk would provide, especially if even at the greater degree to the wind it is possible to make comparable speed. It is difficult for me to make comparisons because my own experience is exclusively as a day sailor where I often have no choice but to work windward, because of this I likely underestimate the additional benefits the junk has on other points of sail. I have principally liked it for its reefing characteristics, a job I am not comfortable doing single handedly on my boat. And I invested a lot in run the lines to the cockpit and installing a reefing system.

    Congratulations on the boat by the way and thank you for the first hand details on Migrant you were able to provide.


    There is also a rig called the Swing-Wing which the JRA considers distinct from the Gallant. The swing-wing is said to have better performance of the two at least by those that have posted on the JRA group. More information could be obtain from Sunbird yachts in the UK which developed and tested it. It is said to tack through 90 and outperform a regular junk on a reach. I am not sure if either have both a means of controlling twist (this could be done with the sheetlets) and a of adjusting camber.
     
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