Converting a Bermudian Sloop to a Junk Rig?

Discussion in 'Boat Design' started by mattnedgus, Oct 6, 2007.

  1. mattnedgus
    Joined: Aug 2007
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    Location: UK

    mattnedgus Junior Member

    Is it possible to convert a yacht with full rigging to a yacht without much rigging and free standing masts? At least in theory... on an old(ish) circa 1950's yacht?

    I ask because it looks less and less likely that building a yacht will be a realistic option - and so I'm looking primarily towards second hand yachts - of which a great deal seem to have the standard sail layout (or a variation of).

    Ideally (after reading the first few chapters of Annie Hills book 'Voyaging on a Small Income') I would like a simple rig - such as the Junk.

    From what I read, my second choice would be a Gaff, although looking at the differences between Gaff and Bermudian, the change shouldn't be too difficult. It's the structural problems I thought it might present that make me unsure.
     
  2. alan white
    Joined: Mar 2007
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    Location: maine

    alan white Senior Member

    Any boat can be converted from a more highly stressed bermudan rig to a gaffer, lugger, junk, etc. without much structural alteration. Free-standing spars are larger in diameter, round rather than oval, and mast relocation isn't always necessary (though sometimes it is).
    Unstayed, a mast bears more on the partners, so the deck would probably need to be reinforced. More leverage is also exerted on the mast step, though extra bracing there is pretty simple.
    Staying a gaff rig means moving (at least one of) the shroud sets back a couple of feet and probably relocating them further outboard (on chainplates), and adding lighter chainplates or anchoring points mid-cockpit for running backstays.
    I don't know much about junk rigs, except to say you might examine the standard Folkboat in comparison with Jester, a modified Folkboat with a junk rig that was once used in an atlantic crossing race. In that boat, all lines were led to a tiny round hatch for one's head to poke out from.

    Alan
     
  3. Eric Sponberg
    Joined: Dec 2001
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    Eric Sponberg Senior Member

    I am currently designing a rig conversion for a 45' gaff cutter to a junk schooner. The builder is a devotee of junk rigs, and recommended a very good book, "Practical Junk Rig" by H.G. Hasler and J.K. McLeod. It is available from a number of publishers--I bought mine from Tiller Publishing (designer Jay Benford's publishing company; he is also a junk rig enthusiast).

    In nearly 30 years of designing free-standing rigs, I have had only one client up to now that has successfully converted a boat from stayed rig to free-standing. This is Copernicus, a Spencer 42, the story of which you can see on my website:

    http://www.sponbergyachtdesign.com/Copernicus.htm

    In the case of Copernicus, the mast stayed in the same location, and additional reinforcing had to go into the hull and deck for the mast step and the partners, respectively, to support the free-standing mast loads. This usually involves dismantling a good portion of the interior--not too bad if the mast stays in the same place, but a real costly modification if the mast moves and/or a mast is added, such as going from sloop to cat-ketch.

    In the other case for the 45'er, the original rig was built so lightly that the hull and deck have to undergo major modification to fit masts of a suitable diameter and to provide extra strength. This is an on-going project.

    I did take a close look at the recommendations of mast size as recommended by the book above for this particular application. The wood masts that the book calculates will work, but the factor of safety over the boat's righting moment (which is the maximum live load the boat will see) is not very great--1.36 against breaking in this case. This is not high. I typically design free-standing carbon fiber masts with a factor of safety of 3 against breaking.

    Eric
     

  4. la cage
    Joined: Feb 2007
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    Location: warragul,australia

    la cage Junior Member

    My method of construction allows a person on a budget to achieve ones dreams. Cheers from down under. Peter Bourne. www.bourneboats.com.au
     
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