What I have learned about planing hulls so far

Discussion in 'Powerboats' started by magwas, Sep 7, 2010.

  1. magwas
    Joined: Oct 2009
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    Location: Hungary

    magwas Senior Member

    Knuckle: A sharp angle formed by the meeting of two surfaces, especially two ship's timbers.
    Stem: The vertical part of a vessel's bow between the waterline and the main deck where the sides of the vessel come together.
    Forefoot: The heel of the stem where it connects to the keel.
    Rocker: An object having a curved form, as the keel of a ship or a skate blade sharpened in a curve.

    Now I understand the suggestion about the knuckle in the forefoot:)
  2. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    What do you "understand" about the forefoot, Magwas?

    Where is the forefoot in reference to what I was talking about?

    Why would it be a good idea to remove depth in this area?

    Why would it be a good idea to remove the knuckle?

    It's not enough to look up the definition of a word. You have to understand the interaction of the various elements. If you can't answer the above, quickly, calmly and without looking each up, then you are wasting your time here.
  3. ancient kayaker
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    ancient kayaker aka Terry Haines

  4. magwas
    Joined: Oct 2009
    Posts: 287
    Likes: 8, Points: 18, Legacy Rep: 47
    Location: Hungary

    magwas Senior Member

    (Please keep in mind that I am not a native speaker (my language have no closer word for this sense of knuckle than "break"), and boat terms are sometimes weird even for natives.)

    You basically said that I should draw the bow part of the ship flatter. This way when the boat jumps to a wave, it will not immerse with the nose. That means that a) the wave won't drive the boat to an unwanted direction, and b) the water won't climb up, which in turn means drier run and less resistance.
    Removing the knuckle means a smoother curve, which basically means that the change of the norm of the surface will be gradual: Besides the obvious aesthetic reason my understanding is that there won't be close-to-flat areas on which a badly got wave would mean a greater hit.

  5. tunnels

    tunnels Previous Member

    You got it ! The English Language is a difficult thing and the choice of words can and is very miss leading no matter the level of education .
    The very front of any boat is important as this is the part of the hull that entres the water / wave and as peed increases it needs to be finer to knife through the wave yet seperate the water quickly and at the same time lift the hull without causing it to thump as it hits . This can make for a very uncomfortable ride
    The other thing is going down the wave and getting to the bottom and still having enough buoyancy and lift not to broach or bury the nose in a dangerous manner . Its really scary in smaller boats to the point of being thrown out of the boat as it comes to a almost complete stop .
    Like i said take a camera and photograph every boat you can find , good or bad . Its all good referance to come back to . I used to walk the pit areas when the boat racing was on and had hundres of pictures of all kinds of boats . I would watch the racing to see what the performance of each boat was like then study the photos to see why one was better than the other , why one boat was able to corner quicker and why some boats were just plain terrible and just sat on there trailers most of the time . :confused: :idea: :eek:
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