Loose footed mains

Discussion in 'Sailboats' started by Polarity, Dec 12, 2003.

  1. SeaDrive
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    SeaDrive Senior Member

    To give an answer to part of the original question: the motivating advantage to the sailmaker was that the it was cheaper to eliminate the the bolt rope on the foot and it didn't make much difference since the foot was only a shelf not transmitting any significant force to the boom. (As remembered from discussion about 15 years ago with Chris Wentz of Z-Sails)
     
  2. brian eiland
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    brian eiland Senior Member

    Boomless Dart, NACRA, & Firefly

    Actually it was the Dart catamaran from England that went boomless, then the NACRA 5.0 at my suggestion. This was around 1985-86 I believe.

    In 1988 I decided to go with a boomless mainsail on my FireFly trimaran. It worked out great as we provided a circular traveler that actually bent inward a little extra at the ends to allow for a fuller main upon reaching.
     
  3. brian eiland
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    brian eiland Senior Member

    Boomless Mainsails, Frank MacLear

    IN MEMORIUM
    * Frank Reynolds MacLear, the noted naval architect died at his home in
    Watch Hill, on Sunday, July 11, 2004. He was 84.

    In a career which spanned nearly seven decades, MacLear stood out for his imaginative boat designs and his ability to translate personal sailing experience into practical concepts. He was an outstanding yachtsman, expert navigator and accomplished ocean racer. The yachting world has lost an outstanding member.

    MacLear worked for the world famous yacht design firm, Sparkman &
    Stevens, Inc. before opening his own firm, MacLear & Harris, Inc., in 1959.
    He participated in more than 700 design projects including commercial and
    military, but focused on large private sailing yachts drawing on his many
    years' experience sailing more than 300,000 miles all over the world.

    He was the inventor and innovator of the boomless mainsail and remote-controlled luff roller furling. An expert navigator, MacLear navigated numerous ocean races. He was the navigator for the 1958 America's Cup challenger Weatherly. He made seven Bermuda races, eight trans-Atlantic crossings and three trans-Pacific crossings.

    (It was Frank MacLear that inspired me to consider utilizing boomless mainsails, and so I will add a few of his designs below)
     
  4. brian eiland
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    brian eiland Senior Member

    Angantyr, cutter rig

    Actually this is not a boomless design, but it was the predecessor to several of his boomless cutters.

    From 'The Proper Yacht', "In a cutter such as the MacLear & Harris designed Angantyr, two sails instead of one are set in the foretriangle. This rig has much in its favor for cruising. Despite her size, the 61-foot Angantyr has been sailed by small crews on most of here passages, which include seven Atlantic crossings. Her owner has made one of the latter singlehanded. Twin centerboards give Angantyr the ability to enter practically any harbor (board up draft is only 5 feet), and to match the lateral plane of the hull to almost any sail combination for good balance."

    She was a powerful cutter rigged world cruiser that could navagate her home based shallow Chesapeake Bay
     

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  5. brian eiland
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    brian eiland Senior Member

    Boomless Cutter

    I believe there were more vessels built to a design similar to those two I post here. But Think you can see there heritage from Antanyr.

    The boomless mainsails are sheeted to the fixed backstays, in this case 3 of them.
     

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  6. brian eiland
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    brian eiland Senior Member

    Updated Mainsails

    Now I can imagine updating these rigs with vertical-battened mainsails....
     

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  7. brian eiland
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    brian eiland Senior Member

    I see where a few of these weblinks are no longer viable, so here is a little update.
    DART catamaran

    NACRA 5.0 catamaran

    Firefly Trimaran
     

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  8. sharpii2
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    sharpii2 Senior Member

    I see mainly three advantages to having a loose footed sail:

    One, the camber depth can be controlled more precisely. Work boats of the 19th century probably used them for this reason. Airfoils were not understood at that time (before the invention of the airplane), but there was probably plenty of empiric evidence that a deeper cambered sail provided more drive than a shallow cambered one. In a strong wind, the sail could be pulled nearly flat by it's out haul to reduce it's power.

    Two, some sail area can be set below the Boom, which tends to keep the Boom from cocking up, as it would without a Boom vang. The Boom could also be set higher, without raising the Vertical Center of Area (VCA) much.

    Three, The sail could be wrapped around the mast, if not for reefing, at least for furling, negating the need for a halyard.

    Three disadvantages I see are:

    One, a stiffer boom is needed. With an attached foot, some of the load of the sail is distributed along the length of the boom, decreasing the bending moment significantly. With a loose footed sail, all the load is on the end of the Boom. A good example of this is an article I read in Small Craft Adviser, where a attached foot sail was replaced with a loose footed one on a Scamp sailboat. The Boom bowed noticeably under the load of the new sail, even though it had the same area as the old one.

    Two, the 'end plate' effect, provided by the Boom, with an attached foot sail, is lost, allowing more of the high pressure on the windward side to leak around the foot, blowing downward, sometimes blasting spray aboard the boat (Bolger commented on this in at least one of his books)

    Three, the clew patch and out haul must be made considerably stronger, probably requiring thicker sail cloth as well. Also, a failure of either the Clew or the out haul can quickly turn the sail into a giant flag.

    Whether or not to use a loose footed sail over an attached footed one is realy a design decision, based on the goals of a particular design, not on one being inherently superior to the other.
     
  9. TeddyDiver
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    TeddyDiver Gollywobbler

    That's true only if the sheeting point isn't at the end of the boom. Generally it's in the end of the boom so there's no bending, just pressure.
    BR Teddy
     
  10. PAR
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    PAR Yacht Designer/Builder

    Ever try to trim a loose foot sail in heavy air? The west coast lumber schooners of the golden age had a loose foot foresail and the first reef wasn't the main, but to douse the unmanageable foresail. Even a boomed sail with a loose foot is difficult to use in heavy air. Round the buoy guys and casual sailors and cruisers can live with a loose foot, as they'll never be out in winds to challenge their will and gear. On the other hand, if you might, you should have an attached foot.
     
  11. Silver Raven
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    Silver Raven Senior Member

    Gooday PAR - You've done a lot of long-distance ocean racing & cruising - have you ???

    As for; Sea Drive - what a total load of 'twaddle' but agian I'm sure you'd know all about 'sailing' efficiently, safely - possibly underhanded - in long ocean crossing as well as - PAR.

    The year we have here is 2012 not "of the golden age" nor are most of us still sailing "west coast lumber schooners" either.

    Are they 'for sale' on Craig-list' or on 'James-list' ???

    Cav - where is "west coast" - your somewhere over there ??? Is that somewhere near Boston, eh ??? Ciao, james
     
  12. rick carr
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    rick carr Junior Member

    a loose footed main makes it possible to get the desired shape or leeward curve from the boom all the way up the sail at the luff whereas if the foot is straight the curve finishes and goes flat from about 8-10 ft up down to the boom with the subsequent loss of power or lift that this curve produces .
     
  13. CutOnce

    CutOnce Previous Member

    Good sail makers cutting good panels can put accurate draft anywhere you want in a sail. On both loose footed and boom-attached sails. We're past Egyptian cotton folks.

    Current sail making technology can effectively reproduce any airfoil section you want, even multiple sections at different levels if required.

    --
    CutOnce
     
  14. PAR
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    PAR Yacht Designer/Builder

    Agreed a good cut is a good cut, but the average boat doesn't have the gear to haul in a boomless main in heavy air, nor do they have custom fitted sails. Maybe it's best to refine the need first. Are we talking about the relative merits of a boomless sail on an application specific craft or the usefulness of the same on a typical sailor? Simply put, if you want a wide range of usefulness, than a boom is required.

    As to an attached foot or loose, both can be made to work, though I've found loose footed sails to be at a disadvantage (on the average boat) to an attached foot in heavy air. Racers can be designed to carry what ever and have enough options and equipment, to make these points moot, but the average boat and crew will not have these options, nor design attributes.
     

  15. gonzo
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    gonzo Senior Member

    Boomless sails have been in use for centuries. Nobody knows who invented them. Modern claims on having "invented them" are just marketing bs.
     
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