Mast question

Discussion in 'Sailboats' started by Southern Cross, Oct 29, 2013.

  1. Southern Cross
    Joined: Mar 2013
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    Location: So. CA

    Southern Cross Senior Member

    I have a keel stepped mast (Olson 30). The opening at the deck where the mast passes through has about 1/2" - 1/4" space around the mast. I found an aluminum deck collar that has several blocks built in for halyards and such that I like. It would create a tight fit at the deck leaving little play. The mast is a double spreader.

    Would restricting movement at the deck increase the risk of the mast failing at this point? Is a little play necessary for mast bend etc or is it not happening so much so low?

    Thanks for your thoughts.
  2. messabout
    Joined: Jan 2006
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    messabout Senior Member

    The mast will move at deck level. Perhaps not much movement but enough so that a rigid connection has the potential for causing other problems. If the mast/deck connection is rigid, then the deck will be subjected to some loads that it did not endure before. The sound of cracking fiberglass could possibly become a costly concerto.
  3. Southern Cross
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    Southern Cross Senior Member

    What I suspected. Sounds right. Thanks
  4. Stumble
    Joined: Oct 2008
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    Stumble Senior Member

    Given that I had spartite poured for my Olson 30 specifically to minimize mast movement at the partners I can't imagine this being a problem. A deck collar seems unessesary on a 30, but it shouldn't be an issue.

    If you are racing it, I would highly suggest getting a Beam of Destiny and keel straps for the boat. The 30 rig puts a lot of stress lifting the deck, and pulling the hull sides in. And they are much easier to install while the mast is out.
  5. Southern Cross
    Joined: Mar 2013
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    Southern Cross Senior Member

    Gregg, thanks. I have the beam of destiny and jock straps but we are doing some other mods to eliminate these altogether. There are a few boats undergoing some heavy mods right now as the class seems to be altogether finished.

    I like the spartite idea. I had not seen this product before so thank you.

    The attached picture is something I was entertaining. I just finished removing all my old hardware and filling the holes and/so I'm looking to minimize the number of new holes I drill through the deck.


    Attached Files:

  6. Stumble
    Joined: Oct 2008
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    Location: New Orleans

    Stumble Senior Member

    Ya, I got out of the boat due to the lack of a OD class, and I really didn't care to spend the money to turn it into something I really wanted to own. I have heard of some really cool additions to the boat, and a local guy has a asymetric rig that works great, but I like OD racing, and the mods I was contemplating just kept going up and up in price :D
  7. bpw
    Joined: May 2012
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    bpw Senior Member

    I am pretty sure most all tuning guides for keel stepped masts say something about making sure the mast wedges are tight to prevent movement at the deck. It's is also possible that the mast sectioned is designed to have support at the deck.

    So get some mast wedges/spartite.
  8. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The partners serve to important functions, the first is to permit enough movement to rake and plumb the stick and the other is to solidly lock it down, to provide the upper hard point of it's purchase. Simply put, once the mast is where you want, it should be firmly captured in the partners and of course have a good seal (boot) for obvious reasons. The are a few ways to do this, some incorporating both a collar and seal holding and keeping moisture out, while other approaches divide the tasks up into a separate purchase and sealing arrangements. Wedges work, though I dislike this approach on aluminum masts.
  9. michael pierzga
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    Location: spain

    michael pierzga Senior Member

    The mast must be firmly chocked in place at the partners. Spartight is the industry standard. Various rubber sheets or chocks can also be used.

    When using spartight , an inflatable rubber innertube must be placed on the mast before stepping. Wheelbarrow or wheelchair size for your small mast diameter

    Both surfaces..mast and deck collar assembly are the coated with vasoline to keep the spartitie from bonding to the surface.

    The inner tube is inflated to create a seal on the botton spartite edge and the spartite is poured into the top.

    Spartite is not used on wooden masts because it may trap water.

    Spartite is applied after the mast has been sea trialed and tuned.

    On some installatintions in which the mast wall is not parralel to the mast collar assembly spartite can make it almost impossible to unstep the mast. If dealing with this scenario you must remove the spartite....not easy. Best to imbed a Cheese wire or string cutter into the spartite when you pour so that you can saw it out

    Spartite doesnt like the sun and since it is recessed into the mast partners it pools water. A conventional mast boot is needed.

  10. Armac
    Joined: Nov 2004
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    Armac Junior Member

    The Olson 30 has a few unique issues with the lower mast. First, it was originally designed with a baby stay, which most boats have eliminated. To keep the mast from pumping, a fair amount of prebend needs to be induced, which is usually done by blocking the mast forward at the partners, and/or moving the mast step aft. In this situation you're creating a bearing point at the after face of the mast, which "shouldn't" be a problem. what is a problem is that there is a large (1") hole drilled in the forward face of the mast ~18'' down from the partners in the tension side as an electrical exit. I've seen horizontal cracks radiating from this hole. It needs to be reinforced. The only advantage of a larger rather than smaller mast hole is that it can be a tuning element- more blocking in a heavy air series, less in the light. For other purposes, block it to fit your sails and set up.

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