Define "Keel"

Discussion in 'Boat Design' started by RHough, Aug 24, 2008.

  1. RHough
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    RHough Retro Dude

    I've always defined "keel" as the longitudinal structural member at the bottom of the hull.

    Are there any NA's that would disagree with that definition?

    If you don't agree, how would you define "keel"?


  2. yipster
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    yipster designer

    keel in my dictionairy gives: push over, making capsize, it also mentions coal and the amount of it in a barge, on an even keel means level, in balance, without effort, steady, quiet

    i was thinking it was more like: bottom, blade, wing or even rudder

    beeing a draftsman al my live i now looked "draft" up in the dictionaity and still dont understand why a beer and airdraft and a sketch all have the same name.
  3. marshmat
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    marshmat Senior Member

    Nobody ever accused the English language of making sense, Yipster....

    Randy, most of my books use the term "keel" for both the lowermost centreline structural member, and for the largest / centre hydrodynamic appendage used to create lateral resistance and righting moment. "Keelson" seems to be used more often for the structural member on the inside of the hull, immediately above (and usually joined to) the structural keel.

    I sometimes see the terms "structural keel" or "keel stringer" used to distinguish the structural member from the hydrodynamic keel.
  4. RHough
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    RHough Retro Dude

    I'm not sure what I expected when I started this thread. :)

    It is noteworthy that common usage seems to equate keel with ballast and lateral resistance on sailing craft.

    Ships have always had 'keels', laying the keel is like the moment of conception, the start of a ships existence:

    Keel Laid
    Build time in ways
    Service Life

    Do power boats have keels?
    Do FRP Hulls have keels?
    Do plated hull ships have keels?

    In other words, if a boat does not have a central longitudinal member, does it have a keel?

    The 'keels' that we hear are breaking off and causing problems for sailboats ... are obviously not the main longitudinal structural members :)

    This is probably going to be a bone of contention in a case before the court in NY ... the definition of 'keel yacht' ...

    Clear as mud ... :(
  5. BHOFM
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    BHOFM Senior Member

    Isn't a "Keel" that real good piece of all white chicken that
    KFC doesn't serve anymore?
  6. RHough
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    RHough Retro Dude

    Damn! I forgot about those ... LMAO!
  7. lewisboats
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    lewisboats Obsessed Member

    The keel is generally the solid centerline of the boat, to which the bottom/sides join, the foils are attached or are an integral part of and the framing is anchored on...but not on all forms or styles of boatbuilding. Witness a Collin Archer carvel design with a full "Real" Keel vs a Stitch and Glue Bilge "keeled" but really "foiled" cruising boat. The S$G boat doesn't really have a "Keel" per se but uses a Monocoque construction. Kind of like an old car that has a body on frame vs the newer Unibody construction with minor "members" to deal with local stresses. The foils are dealt with via dedicated internal support tied into and spread over a large part of the hull via the internal structure which doubles as the furniture of the boat.

  8. LyndonJ
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    LyndonJ Senior Member

    And you could confuse everyone even more if you said that there is no gripe with these types of hulls :)

    Interstingly one of the functions of the gripe was to protect the protruding keel or false keel timbers in the event of a grounding.

    The true keel runs from the cutwater or stem to the rudder post then there's the keelson...........aaah the english spreekt nit so goot eh yipster.:) :) :)
  9. rwatson
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    rwatson Senior Member

    No - THAT keel is the triangular shaped bit of cartilege on the chest

    "the keel — it's the flexible wedge of cartilage connecting a chicken's breast muscles"

    KFC still serves the muscle around it.

    As far as boats go - I thought I knew I knew what a boat keel was, but now I know I dont know :)

  10. sail.scow
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    sail.scow Rrrrrrrrrrrrr!

    Maybe for yachts the 'keel' might be better described as the 'fin'.
    The traditional association of strength that the word keel infers is misleading when used to label a fin.

    I agree that the keel should be the term to describe a structural member of the hull, not a lateral profile. A grid does include a substantial longitudinal member, but not what is ever termed as the keel. However, being precise about it raises eyebrows.
    "From the base line of the hull projects a fin, at the end of which is attached or contains a ballast component.":cool:
    "Ohhh, you mean the keel.";)
    "No, the keel is the major structural member around which your boat was built, and to which the fin is attached."
    :confused:"Well, I guess my boat doesn't have a keel then. You're an idiot red.":p
    The fin of a yacht could be any configuration now. Doesn't help much that the 'keel' is often attached to a 'structural grid' nowadays. Or in a steel yacht, the keel might be a collection of sump, water and fuel tankage in the shape of a beautiful NACA foil.

    What is the difference between constructing a keel from components, and hewing a keel? When the word keel was invented, there was no list of components from which it was built... it was a component

    I am not very precise about it personally, and most people can infer the meaning of a multiple use term, like keel, from the context of the conversation. That's my excuse anyway.:p

    By the way, a big old fashioned scow has a rubbing strake for a keel, and the keelson is the main longitudinal member. If you looked at the plans for one of those big old beasts, you would be horrified to see the spec's for the keel.:D
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