Your Opinions on Deck Stepped Masts...

Discussion in 'Sailboats' started by Alixander Beck, Jan 23, 2006.

  1. Alixander Beck
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    Alixander Beck Junior Member

    Would be appreciated.

    This is for 30' Keel Boats made of Wood.
     
  2. PAR
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    PAR Yacht Designer/Builder

    A deck stepped stick is totally dependant on the rig to hold aloft and in column. This is perfectly acceptable. Keel stepped masts are much more secure and may stand if a wire lets go. I prefer keel stepped poles, but this can be impractical in some boats (usually smaller craft). There is no limit to the size of vessel a deck stepped stick can stand on. A number of modifications may be necessary if converting from a keel step to deck step and this is true in reverse as well.
     
  3. rugludallur
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    rugludallur Rugludallur

    Deck vs. Keel stepped masts

    With wood a keel stepped mast will always be a better choice IMHO and the same goes for composites. For Metal hulls things can be a bit different since they enable a compression post to be placed below decks and welded to the keel frames and topsides giving even better support than a keel stepped mast provides.

    Yours

    Jarl
    www.dallur.com
     
  4. mattotoole
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    mattotoole Senior Member

    A deck stepped unit could yield more cabin space if the mast were supported with a ring frame, beam, or bulkhead instead of a strut or column.

    Having sailed and stepped both types I don't think it matters. It's an interesting thought that a keel stepped mast might remain standing if something lets go, but I can't imagine such a situation. If it's windy enough for something like an upper shroud to break, either rig is at risk of collapse.

    I wonder which is better when the worst happens though. It seems a deck stepped unit could be jettisoned more easily. ???
     
  5. Cliff Pope
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    Cliff Pope Junior Member

    For lowering the mast to pass under bridges, a tabernacle on deck is best!
     
  6. D'ARTOIS
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    D'ARTOIS Senior Member

    The general idea is what PAR stated already - an all over higher strength - shrouds can be spaced more widely - powertransmission of sails to hull is uninterrupted and general loading forces are better divided.

    A practical advantage is that the mast will not tend to rattle. A large Dutch manufacturere gaining more in the making of higher class yachts informed mme that he will only place keel-stepped masts in his present and future boats.
     
  7. zerogara
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    zerogara build it and sail it

    In many cases where the main spar has snapped and there is a lower part of it still in tact, upper shrouds can be cut and still there is a spar to rig up and sail slowly but better than nothing. It is usually a keel stepped design.
    It is very unlikely that a deck stepped mast will lose its top half and still be intact.
    If everything is in tact and balanced there is not much difference to the skipper, if something is not aligned though it can be impossible for the designer to predict what will happen next. The keel stepped mast is much simpler to deal with.
    Question: How simple is it while in calm weather but in the water to replace shrouds or do adjustments to the rig? Which mast feels more comfortable now?
     
  8. Seafarer24
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    Seafarer24 Sunset Chaser

    Something to note:

    If you have a wooden boat, your greatest enemy will be fresh water causing rot. A keel-stepped mast will be a constant source of worry as they can be rather difficult to keep from leaking, and leading fresh water right down to the most vulnerable and difficult part of the boat to repair.

    In my opinion, I'd prefer one less hole in the boat!
     
  9. mighetto
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    mighetto New Member

    Seafarer makes a great point. In addition, if the mast is lost owing to a capsize or knockdown, the keel stepped boat will have a huge hole in the cabin top. It is for this reason that the Volvo 70 designers required that there be a hatch mechanism for closing the hole created by a lost mast.

    The other point regarding keel stepped masts is that in a design where there will likely be water in the bildge at all times, owing to an inboard secondary shaft, the bottom of the keel stepped boat will always be in water. This over 10, 20 and certanly 30 years will eat away both wood and aluminum masts at the base. Most 30 year boats of masthead design have this issue today. Surveyors routinely tell prospects that they will have to remove the mast and fix that issue when boats of a few decades old are purchased.

    Even vessels with outboards suffer because the keel stepped mast will generate its own amount of bildge water just from rain running down it. The unmentioned but also important disadvantage of the keel stepped mast is that it impacts interior design. There is nothing worse than an interior that has the mast poking trough a table in the interior. That makes the table useless for most projects including even dining to an extent. The pole through sleeping quarters is also a disadvantage for cruising couples.

    Frank L. Mighetto
     
  10. zerogara
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    zerogara build it and sail it

    Most deck stepped designs I've seen have a compression pole right under the mast that is sometimes of larger diameter than the fore/aft dimension of the mast.
    So unless you're talking about a massive and ingenious "ring" bulkhead as mentioned before, where is the space saving?
    Those things (sticks) carry 1000s of pounds in compression that has to be countered by something! DO you want to sleep or eat under such a load?
     
  11. aitchem
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    aitchem Junior Member

    My Keel stepped mast is 28 years old and has never leaked at all.
    Maybe your'e talking about McGregor standards of construction here.?
     
  12. yipster
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    yipster designer

    a -freestanding- mast al the way down supporting, not stepping the keel ever done ?
     
  13. PAR
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    PAR Yacht Designer/Builder

    There's no doubt that keel stepped sticks are inherently more securely positioned in the boat. Free standing rigs require it, or must rely on the same principles for support (step and partners) Offshore craft prefer them and if not a flimsy racing pole, then will stand with one or more wires let go. A deck stepped mast will go over the side, though may be recoverable, likely not easily used for a temporary emergency rig to get back to port. A keel stepped stick often will have a considerable stub that a sail can be rigged on (or reaching stick lashed to), permitting it to continue to port.

    All this talk about water in the bilge and leaking sticks and mast boots is little more then fodder for poorly maintained vessels. All poorly maintained vessels will have issues like this, plus a host of other issues. Mast boots aren't difficult to upkeep (several manufactures of newer styles are very water tight), nor is keeping water from entering the mast. Mast steps are usually pretty high in the bilge, bridging atop the floors. If you're carrying enough water to cover your floors in a vessel you have bigger problems then a leaking mast boot.

    I just built and installed a keel stepped stick for a 30'er. The keel stood 4" proud of the bottom planking and the floors several inches above this, which the step bridged four of them (pretty typical). This means, if the mast heel was to live in bilge water there would need to be nearly a foot of water in the bilge. If you're dragging around this much water, then you have bigger problems to solve.

    I can see some of the older style (CCA, etc.), built down section hulls having issue with this, as the bury is substantial, well into the belly. There is no excuse for a leaking mast or boot, blaming the design concepts isn't the answer, performing the required maintained is. There's also no excuse for leaking stuffing boxes, with what's available on the market today.
     
  14. Windvang
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    Windvang Yacht Designer

    Some free standing wingmast rotate around a carbon pole build into the structure of the yacht.
     

  15. D'ARTOIS
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    D'ARTOIS Senior Member

    Keel stepped masts leak only (a tiny bit) through the groove of the mast. A bun, placed under the maststep will keep the water and from time to time will be emptied.
    No big deal unless you are looking for nails in eb tide......
     
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