Help Needed: Changing a keel step mast to a Deck stepped mast!

Discussion in 'Sailboats' started by jfranta, Feb 2, 2015.

  1. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    The mast, rigging and internal structure must be re engineered if you change from keel to deck stepped. You will only get an answer for your question by hiring a naval architect to inspect you boat then calculate all engineering factors .

    Your mast and rigging may be up to the task...only an engineer can determine this.
  2. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    A friend of mine had a low aspect rig on a sharpie. He cut the mast and step that bridged the coach roof. They never had a problem in over ten years. It depends on the setup.
  3. TANSL
    Joined: Sep 2011
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    Location: Spain

    TANSL Senior Member

    jfranta, you know how you should proceed: do not worry about anything, do what you want without taking any precautions and, if you have any problems, you claim to Gonzo's friend.
  4. Martin B.
    Joined: Aug 2013
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    Location: Mandurah, Western Australia

    Martin B. Junior Member

    Before you get too far into Euler, is this an "early" aluminium mast or a timber mast ?
    If aluminium then how the hinge/ pivot is arranged is a major factor.
    A number of aluminium masts in my home town ( which requires mast lowering to go ocean racing) were made with the mast cut at about 60 degrees to horizontal and provided with heavy plated ends to the stub and the main mast section itself. When bolted up tight, the mast acted like a one piece keel stepped spar from the structural/Euler point of view.

    However many other Perth masts were merely pivoted on a substantial pin in a tabernacle where the tabernacle was bolted thru the deck to a mast support post under the deck. Big difference in bend characteristics.
  5. JSL
    Joined: Nov 2012
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    Location: Delta BC

    JSL Senior Member

    We are in need of a few letters stating the risks associated with changing a keel stepped mast to a deck step mast by cutting the existing mast off and making a deck stepped mast. No change in rig design. Boat and mast are 45 years old.

    We need letters from Naval Architects or Designers. You will be compensated for this.

    As before and as you requested- Hire a professional to review the rig (and vessel, installation, etc) & do the work.
  6. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    This isn't that difficult or all that unusual a situation to work with, from a professional point of view. Jfranta, I'll assume you are part of or are looking to hire, a legal team to peruse an issue that has come up, possibly involving some claim about one or several of your products.

    Your questions thus far have been ambiguous at best, so some detail will be necessary, though generally, your staff will have the necessary answers you need, with the exception of a NA sign off of the specifics of the situation (were the parts and/or assembly the reson for the failure, etc. and more assumption). Given that Colligo Marine is a product development house, part of this would be certification of the engineering involved. This suggests you or those you hire/vendor with will have had specifications and application approaches not only addressed, but qualified and certified.

    Simply put, if you have a claim and need certified engineering, it's likely you have a vendor or staff that can perform this task, covering the specifics, if not hiring an NA to represent your position, shouldn't be very difficult to place for a company like your to be in. I would go as much to suggest you have favored NA's you've previously worked with and this relationship could be exercised, if to save the bother of finding a new, unfamiliar NA to work with. In your area there are dozens to choose from, though just running down to CC Rigging or calling Mike Leneman at MultiMarine - a short discussion will set you straight pretty quickly.

  7. water addict
    Joined: Jun 2004
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    Location: maryland

    water addict Naval Architect

    The obvious risk is the mast will fall down, other connected gear could break, and someone could get injured or killed.
    If you are asking what might be root causes of those risks, you need an engineering assessment of the specific case. There is no generic "blanket" statement that any qualified engineer would, or should, give you with the info you provide, as law and liability are involved, the engineer is putting his career at stake.
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