Telescopic masts again

Discussion in 'Sailboats' started by yipster, Apr 25, 2012.

  1. yipster
    Joined: Oct 2002
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    yipster designer

  2. BATAAN
    Joined: Apr 2010
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    BATAAN Senior Member

    Oh, so that's the deal....
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Some folks just get paid to dream up ridiculousness. Cost effective sail assist isn't practical in these sizes. You can do it, but the amount of under keel miles to amortize the costs, of a possably telescoping, carbon rig, of this size and complexity, oh please. The weight study alone will force the owner to kiss off a substantial portion of it's profit, just to carry the rig.
     
  4. sharpii2
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    sharpii2 Senior Member

    Interesting concept.

    Just that the ship goes so fast under power (do to it's length), I don't see these sails can be much help.

    Also, the more masts you have, the less windward ability your ship has.

    Many, many three masted schooners were built during the late 19th and early 20th centuries. Fewer, but still many four mast schooners were built. Fewer five mast ships were built, and only one seven mast schooner was built.

    I would think the shipping company, instead of putting up sails, to save on fuel costs, would simply add more containers to off set them.

    a 1,000 foot ship probably steams at around 22 to 25 knots. It would probably take a gale to produce the kind of winds that would help at that speed.

    Otherwise, you will be dealing with apparent wind, which is why I brought up the bit about multi masted schooners.

    The deal looks a whole lot sweeter, as the ship's Length shrinks to about 300 feet and under. A 300 ft vessel probably steams at about 12 kts. At that speed, the wind might actually be more helpful. On some days, it might be able to propel the ship all by itself.
     
  5. Petros
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    Petros Senior Member

    Well, it was likely a cleaver way for a small consulting firm and some collage professors to get some government money to play around with.

    They claim 25 to 35 percent fuel savings? Maybe for short stretches when conditions are right, but even than it is questionable. No way on long voyage. You also have to weight that against double the maintenance cost, perhaps 20 percent more up front costs, and against the losses it causes when stowed (weight, lost cargo capacity, and extra windage even when retracted). It does not sound like a good plan to me.

    A 5 to 10 year break even point? wishful thinking. they should just invest in Apple stock, better more reliable return on investment.
     
  6. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The logical application of all that carbon and other exotic materials in the rig, is to apply these same light weight materials in the structure, freeing up weight, so they can save fuel or carry more product.
     

  7. rob denney
    Joined: Feb 2005
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    rob denney Senior Member

    Interesting timing.

    I have just laid up the inner skin of the top part of an unstayed telescoping rig for my 7.5m/25' proa. The bottom section is 7.1m long and sits on a stub mast with boom attached. The top section is 7m long, bury 500mm. Both are wing sections, 400 and 450mm chord respectively. The sail foot is 1.8/6'm.

    I intend to hoist and lower it with a multi purchase line, but only when the rig is weathercocked with no sideways load. The weight and complexity savings from this are significant. The two parts will be a rattling fit, so friction should not be a big issue, although jamming might be.

    This is a step along the way to a telescoping wing rig on an 18m/60' harryproa being built in Norway. If my rig works, the next one will be a 3 section, 2 element full wing rig for a 9m harry.

    There are some not very good pictures of the boat and the lower mast construction at http://au.groups.yahoo.com/group/harryproa/photos/album/1947136348/pic/list?order=ordinal and description of the build and sailing at http://au.groups.yahoo.com/group/harryproa/?yguid=312404726

    Sailed last weekend with the lower rig (about 11 sqm) in sub 10 knot breeze. Hit 7 knots easily, so should get along pretty well with twice the mast height and sail area, assuming it can be controlled.
     
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