Mast that can be lowered?

Discussion in 'Sailboats' started by jmomcal, Aug 6, 2013.

  1. jmomcal
    Joined: Aug 2013
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    Location: Huntington Beach

    jmomcal New Member

    We live in the Huntington Harbor and would like to switch from a powerboat to a sailboat. Unfortunately, there is a bridge with a 24 ft clearance that is limiting our choices. We've looked at Macgregor 26 ft boats with a mast that lowers but we would like a boat that is a bit bigger. Is it possible to fabricate a mast lowering system on a 28-30ft sailboat. If so, any suggestions on where to have that done?
     
  2. jehardiman
    Joined: Aug 2004
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    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Yes, it has been done for centuries, mostly on river barges, lighters, junks, and hoys. It takes the right type of deck, house, and mast-step/tabernackles to make it work well with the hull, but any compentent shipwright/sparmaker should be able to put together a working unit. Google "mast tabernacles" for lots of examples.

    Just remember that you are not going to get something that goes up like a jack-in-the-box. You will still have to tension the rig, so it works better with traditional pole masts rather than modern multi-spreader rigs.
     
  3. Martin B.
    Joined: Aug 2013
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    Location: Mandurah, Western Australia

    Martin B. Junior Member

    Tabernacles and mast lowering

    Hi jmomcal & jehardiman,

    Virtually all yachts in Perth, Western Australia have hinged masts or masts pivoting in tabernacles as there are two low bridges to pass under en-route to the Indian Ocean.
    Below is a deck stepped tabernacle equipped mast on a 22 square metre (38') yacht. Note that the pivot pin is high enough for the lowered mast to clear the cabin top; also see in the bottom right hand corner of the pic that the chainplates have S/S triangulated fabrications to raise the lower anchor points of the shrouds to directly in line with the mast pivot - this is necessary to stabilise the mast sideways during the very short time you take for the actual lowering or raising action. The heel of the mast is curved to the radius of the pivot bolt-to-footplate of the tabernacle to provide the necessary clearance when lowering: note that the mast actually sits on the front 55% of it's foot and the pivot pin/bolt does not carry the mast axial load.

    [​IMG]

    Here is the same 22 square metre 30 years later - the same arrangement still in operation !

    [​IMG]

    For yachts from about 23' upwards you need
    a.) two spinaker poles
    b.) a solid deck fitting near the chainplates from which they can pivot
    c.) a multi-part tackle you can attach to the forestay or jib halyards for the lowering
    d.) a solid "boom crutch" which is re-applied for the mast when lowered

    To simplify the lowering process and the setting-up of the rig after lifting, we use a highfield lever on the backstay to relieve the rigging tension thereby allowing one to detatch the forestay.

    It is not too difficult to get the modifications done if you have local access to aluminium fabrication/fabricators.
    Obviously you also need a mast support post under the deck down to the keel for deck tabernacle mounted masts.
    BUT in the mid 1970's a local spar maker started cutting aluminium masts on about a 70 degree angle from horizontal, adding (sloping) flat plates to each piece and putting a hinge pin on the aft side of the sloping plates. When the mast was up in position a couple of bolts go thru the front (lower) edge of the sloping flat plates to give continuity of mast stiffness.
    This method was intended to maintain the mast curvature/bending characteristics of a one piece keel-stepped mast which was considered to be necessary (by others, not by me - I was quite happy with the deck mounted tabanercle shown above and on my other 2 ocen racing [under-the-bridges ] yachts).
    If you need a better description then PM me direct mcbunny09@gmail.com
     

    Attached Files:

  4. Skyak
    Joined: Jul 2012
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    Location: United States

    Skyak Senior Member

    I planned a mast lifting setup for my trimaran that might be a little simpler. I dropped the mast forward using the boom for the gin pole. To get the hinge in the shrouds I planned to splice in a toggle in the axis of the pivot and run cable from each of those toggles to the end of the boom. It's not as stable as solid triangles, but if your mast hinge can take a little slop it will work in calm conditions. If your mast hinge can't take some slop it's doomed the first time you move the mast without the rigging set perfectly no matter how the shrouds are hinged. The attraction of my plan is that there is just one small cable to stow. Note: my mast is only 36 foot so I can lift the bow end over my head to start.
     

  5. jehardiman
    Joined: Aug 2004
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    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Yep, that's the way to do it if the shroud arrangement supports it. A fractional rig without double lowers helps. Double lowers can complicate the issue, like they do on my Catalina 22 trailer sailer. About 5-7 min to raise or lower and as much to re-tension.
     
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