a noob question

Discussion in 'Boat Design' started by TheChillPrince, Jul 5, 2016.

  1. TheChillPrince
    Joined: May 2016
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    TheChillPrince Junior Member

    can someone tell me what those things are called on the bottom of the boat in the picture i have attached? looks like three lines? thanks

    pic454m1.jpg
     
  2. SukiSolo
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    SukiSolo Senior Member

    In UK terminology, the central one would be called the keel and the outer ones bilge keels. They are the primary points the hull rests on when beached. They are intended to take the scuffing and be replaced if excessively worn. The keel is often further protected by a metal or plastic band - the keelband (usually brass or aluminium) screwed or glued and pinned for plastic ones.

    If you get serious about racing, the fairing of these parts assuming you have to have them, becomes quite important.
     
  3. PAR
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    PAR Yacht Designer/Builder

    On a boat like that, all of those are rub strips and as their name suggests, they protect the flat boat bottom from abrasion. As Suki mentions, quite often the one on the centerline is a keel, though more often than not, it's a batten (keel batten) or sometimes called a false keel and these serve the same purpose as rub strips. Flat bottom boats of that size generally don't need a keel. A keel batten or false keel is simply a sacrificial piece attached to the outside of the keel proper, though I'll bet that boat doesn't actually have a keel timber, just a few frames and some plywood over chine logs and sheer clamps.
     
  4. jehardiman
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    jehardiman Senior Member

    As PAR said (or similar), I (US terms) would call those rub strakes. Like Suki implied, they are what the hull rests on when pulled up on a beach and generally should have some form of metal or plastic wear surface.
     
  5. TheChillPrince
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    TheChillPrince Junior Member

    thanks for answering my question everyone, now that i got that answered i am wondering if you guys could tell me what that piece of wood is called going along the side of the boat? i should have asked this in my original post. thanks again for any answers i might get.
     
  6. daiquiri
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    daiquiri Engineering and Design

  7. PAR
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    PAR Yacht Designer/Builder

    The sides (topsides) are planks and they could be solid timber or plywood. Because there's more than one, they're (planking) strakes. We could tell you more about it, if we could see the inside of the boat. I'm betting it's a taped seam build, but is could just as easily be a plank over frame build as well.

    The image link above at PhotoBucket, has several debatable terms that I have issue with, though most of it is correct.
     
  8. daiquiri
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    daiquiri Engineering and Design

    Then perhaps it would be a good thing to discuss them here? Might help folks whose primary language is not English (like me) improve their technical vocabulary. :)
     
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  9. PAR
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    PAR Yacht Designer/Builder

    The first thing that struck me was a line pointing to sole, yet labeled floor, so I quickly looked around and found others.
     
  10. daiquiri
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    daiquiri Engineering and Design

    LOL, now I know what you mean when you talk about soles in boat-construction threads. ;)
    I have always known the transverse bottom framing as floors (in contrast to transverse framing of decks, which are beams). But I have learned from formal technical literature, I guess in small boatyards the slang term "sole" is more used?
    Ship structure.gif
    http://www.marineinsight.com/naval-architecture/design-of-ships-bottom-structure/
    http://www.brighthubengineering.com/naval-architecture/32007-basics-of-ship-hull-design/

    Anyways, I agree that the photobucket picture in my previous post is somewhat debatable, at least when confronted with the terminology used in shipbuilding industry. The term "floor" is used there to indicate the bottom plating (which is then what you call "sole", right?) and the term "headers" to indicate floors.

    This might become an interesting discussion, if other knowledgeable folks jump in. Noob questions often turn out to be the fundamental ones.
    We might find out that we are all noobs to someone else. :)

    Cheers
     
  11. daiquiri
    Joined: May 2004
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    daiquiri Engineering and Design


  12. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    No, you have it correctly and transverse members are floors and the soles are what you might walk on, unless they're decks, which are typically exposed to weather, though in a small boat, I'd guess everything is exposed to weather, so . . . If the bottom planking is walked on (small craft), it's still bottom planking.

    [​IMG]

    This is the image I have issues with and I see several. Firstly, many terms get misused or intermingled with others. For example I often call a sheer clamp or shelf an inwale on small craft, while retaining the term shelf and/or clamp for larger craft where they represent an actual clamp or shelf.

    Above the side deck beams are being called gunwale spacers, the cockpit opening carlin is being called an inside gunwale, there's also and inside and outside keel and the main longitudinal stringer is a batten. I could go on, but it's a poor representation, poorly notated and illustrated as well.

    [​IMG]

    This drawing is better, but also calls the sheer clamp a beam/shelf, though these terms (and boat parts) are often mislabeled for some reason. A sheer clamp is an internal longitudinal, that sandwiches the frame heads at the sheer line, helping stabilize them in this usually heavily loaded position. A shelf (sheer shelf) is as the name suggests and a horizontal spacer, placed between frame bays, often just below the clamp, though it can also butt into it and even form a "T" kind of thing. Missing from this drawing is a sole, but commonly they fall on stringers and cleats (sometimes called risings) fastened to the frames and other elements. In small craft the sole might be referred to as bottom or burden boards, dating back to the days when the boat might have a 1/2 a ton of fish (the burden) tossed inside. These are usually removable, fore and aft slat like arrangements.

    In short it's pretty damn confusing and makes taped seam construction a whole lot easier to cope with, terminology wise. I use to have a cutaway of a clipper section with the parts named, including the spars. It was a very well drawn piece with lots of detail and notation. I'll see if I can dig it up.
     
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