physical description of "hooking"?

Discussion in 'Powerboats' started by pcrussell50, Jan 4, 2010.

  1. pcrussell50
    Joined: Jan 2010
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    Location: santa barbara, ca

    pcrussell50 New Member

    I'm fairly new to boating, but have an engineering degree and competent mechanical skills, [the ability to assemble a motor, for example].

    I have the vaguest recollection in my year and a half in boating, about a phenomenon called "hooking", if I have the right word. It is when the bow comes back down on the back side of a wave and the boat tries to slice one way or the other. One of my boats a 1960 fiberglass runabout does this on occasion. It's infrequent enough that I haven't been able to pin down the exact circumstance that causes it. I _think_ it's more prone to happen when I am the only one in the boat and it lists to starboard a little bit in cruise, [it's small, 13', and light, and not too beamy]. Like a lot of vintage runabouts, it's got vee in front, and gently rounded in back, with a "keel" or spine all the way to the transom.

    Anyway, I was looking for a description of the physics or mechanics behind this phenomenon, [as well as it's proper name]. It scared me today.

    FWIW, I tried to search for it under the term "hooking".

    Regards,
    Peter
    Santa Barbara, CA
     
  2. mark775

    mark775 Guest

    "Hooking" works, for me but try "yawing", that will lead to "broaching" in your search.
     
  3. tom28571
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    tom28571 Senior Member

    I call it "bow steering" and it is a common problem.
     
  4. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Yep, I call it "rooting" or bow steer and it's a fair common oddity. For a moment, usually in confused conditions or when you cross a wave pattern that is just right, the frictional resistance of the hull changes dramatically for a second or two, until the sea runs back under the belly of the boat. The bow will root around, maybe steer on it's chines or lift strakes, possibly just from uneven pressure distribution along the hull. There's not a lot you can do about it. It's a function of an unpredictable sea.
     
  5. Submarine Tom

    Submarine Tom Previous Member

    I've experience it in an over powered Boston Whaler.
     
  6. gonzo
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    gonzo Senior Member

    I think you can get educated on it in any corner in the bad section of town.
    Boats with deep narrow forefoot tend to do that.
     
  7. mark775

    mark775 Guest

    I misunderstood.
     
  8. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I used to have a early 60's Lyman that was really bad about it. It had that "destroyer" bow on it, with a lot of forefoot and it rooted around in the back of wave frequently. It's like it was looking for potatoes or something.
     
  9. tom28571
    Joined: Dec 2001
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    tom28571 Senior Member

    Such a bow will also try to throw the crew to one side when running into a head sea at off angle. I had one that tried to chuck me out many times. Problem was a too deep and too sharp bow with too little buoyancy. Make such a bow on a boat with a broad and flat stern and you have a recipe for disaster.
     

  10. frank smith
    Joined: Oct 2009
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    frank smith Senior Member

    I made one like that , Ok boat , but I would cut it up before it got into anyone else s hands. Over powered down east skiffs can be like that, to little buoyancy down low, mixed a lot of flair.
     
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