Keel stepped vs. Compression post

Discussion in 'Boat Design' started by rickinnocal, Jul 12, 2010.

  1. rickinnocal
    Joined: Jun 2010
    Posts: 35
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    Location: Berkeley, CA

    rickinnocal Junior Member

    Hi all, I posted this in "Motorsailors", but I think this might be the better forum.

    My new project, a 54' Calkins motorsailor, has never had a mast stepped. She has chainplates, and was drawn for a sailing rig, but it was never installed.

    The original drawings call for a mast of 50' above deck level, stepped on the keel, so about 57' total. My local yard, where I'm having the boat hauled soon, has a 48' wooden mast from a wrecked boat available. Were I to cut a hole in the deck and keel step this stick, it would be only 40' above deck level - a lot shorter than is called for. However, a couple of people have suggested that, since there is no hole in the deck, I should keep it that way, and mount a steel compression post from the keel to the underside of the deck, bolted through the deck to a mast step.

    Some googling has led me to a number of discussions of the alternatives, and I see very little downside to going this way. Do any of the designers on here see a major problem of any sort with it?

    Richard
     
  2. Paul B

    Paul B Previous Member

    I suggest you contact Doug Peterson in San Diego. He worked for Skip Caulkins and may have knowledge about the boat, the construction, and the possibilities.

    Doug owns 2 Caulkins 50s.
     
  3. rickinnocal
    Joined: Jun 2010
    Posts: 35
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    Location: Berkeley, CA

    rickinnocal Junior Member

    I have talked to Doug via emails, but he doesn't remember anything about the conversion project at all. Until I found design drawings and correspondance from Skip, I think he suspected someone else - maybe the builder himself - had done the conversion drawings.

    I didn't know Peterson owned one. He didn't mention it. I already knew he owns 1/3 of Sabrina with Skips son (also Skip) and another owner.

    Richard
     
  4. Paul B

    Paul B Previous Member

    Too bad Doug didn't have any good input for you.

    Doug and Chris have owned Cathleen together, and also Sabrina. Last I knew they still had both, in some form of partnership or another. I think Ed Reynolds is also involved with one or both boats.


    To address your initial question, a deck stepped mast needs to have much higher moments. If the mast you have sourced is not stiff enough you will be seeing a gravity storm at some point.
     
  5. rickinnocal
    Joined: Jun 2010
    Posts: 35
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    Location: Berkeley, CA

    rickinnocal Junior Member


  6. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    A mast stepped on the keel can have a smaller section because it is pinned at two points. You can always add the extra section with a factory made sleeve and step in on the keel.
     
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