Junk rig on modern hulls

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

  1. Tad
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    Tad Boat Designer

    TsaiHung1.jpg

    HA! We all have stories of builders who did not pay.......

    This is one of the Greenwich built boats, owner reports she's slow but imensly comfortable......
     
  2. BATAAN
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    BATAAN Senior Member

    Tad, thanks for setting me straight on how many different Chinese rig influences have been felt on the BC coast. Allen was one of many, of course. The result is a delightful presence of Chinese rigs on various hulls, some of them conservative, others bizarre.
    It is awesome you have CHINA CLOUD's original hull lines on the back of a chart. That to me is an artifact of BC history.
    In the SF area for many years was FREE CHINA, a 70' junk built in the 1870s and sailed to USA by some Chinese guys who decided not to stay in Mao's paradise. This was 1955. Here's some brief sailing footage.
    http://www.chinesejunkpreservation.com/
    When Harry Dring had it in the 1970s I got to crawl all over for several hours really taking a lot of notes on the construction. A marvelous little ship and so very different from what the norm is these days.
     
  3. DCockey
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    DCockey Senior Member

  4. goodwilltoall
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    goodwilltoall Senior Member

    What do think of Chris Morejohn junkrig? To me it looks like the ideal modern junk.

    The dipping lug is my favorite, are there any chinese versions of such?

    What size were the wood battens that kept breaking? How long?
     

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  5. BATAAN
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    BATAAN Senior Member

    This design seems like it should work, but I am not a Marine Architect so that is strictly an opinion from looking at the drawing. It might be tender and need a lot of ballast. Has one been built or is this just a drawing?
    Dipping lug is wonderful to windward and I had an 18' boat with one back in the early 70s. Only problem is tacking, which is slow and difficult. I don't know of any Chinese versions but there probably are.
    DL was used widely in European fishing boats due to simplicity, efficiency to windward and ease of keeping most of boat clear for fishing.
    I'm not sure what you mean by the 'wood battens breaking'. BERTIE has always had 6061t6 Aluminum pipe for battens, the upper ones doubled with a smaller one inside for more stiffness.
    Other things have broken however.
    The main halyard block failed several times (last one was $400 hi-test Harken) until I bought an all steel, 5 ton capacity, industrial block for $36, made in China, intended for logging and fishboats and have had no trouble since.
    Broke the boom and two battens in a bad knockdown off Punta Gorda a few years ago, but being Aluminum the battens were easily fixed by sliding a next-size-larger piece of pipe over the break.
    The battens have a lot of strain and need to be strong and stiff, no matter what material. I prefer Aluminum for a lot of reasons, one being I have enough maintenance to do without dealing with wood or fiberglass battens since Aluminum does not mind rain or sun so can be ignored for many years at a time, and the tubing is very stiff giving good sail shape, and easy repair.
    We always use the sail covers to preserve the large investment in the sails.
     
  6. DennisRB
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    DennisRB Senior Member

  7. BATAAN
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    BATAAN Senior Member

    The yards on that Chinese rig seem to have their halyards slung too far forward and are too horizontal in my opinion, and Sharpies require a light rig aloft for good performance and the CR is usually quite heavy for the sail size.
     
  8. goodwilltoall
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    goodwilltoall Senior Member

    You are saying Chinese rigs should be considered less worthy for certain boats because of weight issues,and slower speeds. Sharpies are known as fast boats, a smaller CR rig would work, it just wouldnt be as fast. I like the CR, and this is just an observation of accepting certain consequences for other benefits.

    Maybe the last top portion of sail on Morejohns junk rig should be raked, but the rest of square, high aspect plan looks good.
     
  9. BATAAN
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    BATAAN Senior Member

    A sharpie's 'chinese lug' should not have a yard, but a headboard instead, giving a strongly fanned leech and a lot less cloth and weight at the head, and very light cloth and 4-5 mostly parallel battens. Light, light, light and it will work fine. Sharpies are light displacement with easy lines and don't need the brute force that something like BERTIE does.
    Given a tall unstayed mast, say bird's mouth built spruce or whatever, but as light and stiff and chafe resistant as possible. Sharpie's moderate resistance to heeling doesn't strain the rig because she gives to the gusts. You do need some sort of backstay for going downwind when the boat won't heel and relieve herself. I broke a CR mast off at the deck in a boat many years ago doing just this. It was a real rush at the time and quite a surprise.
    With CR chafe is always an issue, the mast chafing the sail and the battens chafing the mast. Modern approaches work with varying success but a carbon fiber mast with a urethane finish is very smooth and would work well. Glued wood has various problems mostly regarding finish and keeping moisture out, but modern finishes properly applied can give a very good result.
    BERTIE is the exact opposite type of boat from a sharpie with her large displacement and immense stability/stiffness and as a result has a stayed, grown-stick mast.
    This allows me to go with a cooked-in vaseline finish that is very long lasting, incredibly cheap and easy to renew, totally water-repellent down in the checks where it matters and other nice things but this is a grown mast with no glue joints to worry about.
    Intensely research what others have successfully done, and also what designs have failed and why. Usually something that has been around for at least 100 years works well, and sharpies are certainly older than that.
    Check out the book GOOD LITTLE SHIP by Vincent Gilpin for a good sharpie design read.
     
  10. sharpii2
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    sharpii2 Senior Member

    The boat in the drawing is really not a sharpie. It is really a flat iron skiff and a quite burdensome one at that. With a displacement of 26000 lbs on a 32 ft WL, it has a D/L of almost 400. A typical sharpie would have a D/L of roughly half of that. With a 10.75 ft Beam (probably closer to 9.5 ft at the WL), this boat should have some impressive initial stability.

    I do agree on your comments about the yards. IMHO, they are under too much bending stress, and may tend to droop under the weight of all those battens.

    The ones you have on BERTIE are slung so vertically, that much of the load on them is compression. With the ones in the drawing, they are under almost pure bending.

    They would need a deep section area and would probably have to be hollow to work. Being hollow, they would be quite buoyant and could help keep the boat from turtleing, if it ever suffered a severe knock down.

    I designed a similar yard for my LOLA concept. They ended up designed to be made of a 1/4 inch plywood box section, which tapered at both ends. It would have a solid timber core which was about one third the length of it.

    To calculate the maximum load, I drew the sail on its last reef and used the maximum righting moment of the hull.

    I soon found that, instead of getting 180 sf for a 3,000 lb boat, I was only going to get 140 sf, with a single balanced lug. Any larger than that, the rig would make the boat too tender.

    I ended up shortening the sail further, to 120 sf, moving it forward, then adding a 42 sf, leg-o-mutton mizzen.
     
  11. BATAAN
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    BATAAN Senior Member

    Sounds like you are on a good experimental path and have thought about it. Next is build and test....
     
  12. justj
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    justj New Member

    I too have a boat with grown sticks that are going to need replacing later this season. As this is my first attempt at replacing the masts I was wondering if you could give (or point me to) any more info on the masts you mentioned? Thanks BAATAN! (in advance).
     
  13. BATAAN
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    BATAAN Senior Member

    The basic idea is go to the woods, cut down a tree, whittle away at it where appropriate, then stick it in the boat. I don't know if your boat is an open day sailor or a 300 ton schooner, but the process is the same.
    Read Chapelle's BOATBUILDING for the basic how-to.
     
  14. ImaginaryNumber
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    ImaginaryNumber Imaginary Member

    Bataan,
    Would you mind commenting on your Vaseline finish? How is it made, and when is it appropriate, or not appropriate, to use?
     

  15. BATAAN
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    BATAAN Senior Member

    This is appropriate to use on gaff, lug and Chinese rig masts made without laminating, solid poles, and is usually found on larger ones. This treatment is used in the area where the sail works up and down, while the mast head and below decks portion are usually painted or varnished. Smaller masts are less labor to re-finish and tend to be found on highly finished boats so over-all varnish may be preferred on such craft for appearance and also because they are little used. Vaseline gives a look much like varnish but usually darker.
    Lay the mast horizontal on horses, preferably in hot weather in the shade. Assuming this is a new mast and we have finished sanding it, apply 10+ coats of Deks Olje #1 (a penetrating Danish marine oil finish) until the wood won't soak up any more, turning the mast to saturate all of it. Be extra careful to soak the checks full. Penetrol or Tung oil can also be used here but I used Deks.
    Don't use linseed oil as it turns black and hosts bacteria.
    Let the mast sit a day or two. Go to the local supermarket and buy 3 pounds of Vaseline for a 40 foot mast. Using a heat gun, warm the wood a small area at a time but not enough to scorch it. Rub the Vaseline in vigorously with a small rough towel while applying the heat gun to melt it, again running it down into any checks.
    Continue until the entire unpainted portion of the mast is saturated and well rubbed-in.
    When properly done the wood should have a waxy feel to it and there should be no excess on the surface.
    Repeat the vaseline treatment yearly working from a bosun's chair. This does not turn black like linseed oil, makes the wood quite waterproof and helps gaff or chinese sails go up and down easily.
    In the 'old days' this was done with tallow on big gaff schooners and such but Vaseline is better and easier to get. I can re-do BERTIE's mast single-handed in a couple of hours for less than $10.
    Every 5 years or so I scrape the surface with a carbide scraper before renewal, just to get the dirt off and brighten things up.
    BERTIE's mast has had this finish since 1985. Photo shows mast before renewing finish this year when it was out of the boat for its 10-year maintenance, so is what it looks like after a year or so of use.
     

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