What defines a hull designed for planing

Discussion in 'Boat Design' started by Mik the stick, Feb 6, 2013.

  1. Tad
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    Tad Boat Designer

    Care to quote a reference on that? I have a new 270 Mt 2200HP Ship docker in front of me (Renegade built by ADB Vancouver 2012). That's about 275 pounds per HP, another 5000 HP Ship docker is 830 tons, that's about 377pounds per HP, considerably more than any speed boat I know of.......
     
  2. tom28571
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    tom28571 Senior Member

    I noticed that too Tad. Tugs are very heavy things and speed is not one of their attributes. Bollard pull is probably their main requirement.

    In Gonzo's defense, I also don't think power to weight is the defining factor of a planing boat. Its necessary but, as my teachers would say, not sufficient.

    My boats plane easily with over 50#/hp, at least up to 70. Have not loaded one past that. Like that definition of planing thread, I don't think there is one answer to this one either. There is a whole bag of hull and equipment attributes that tend to promote the ability to plane but not one of them is a guarantee, taken alone.

    I also don't agree that anything will plane if given enough power.
     
  3. Tad
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    Tad Boat Designer

    Two problems here.....

    The 55 lbs/ton resistance does not apply to a short/fat overweight hull. And a real steel DD 38 built by Kimley in China is a lot more than 32,600 pounds. The first ones floated something like 8-10" deep, so well over 40,000 pounds with a D/L ratio approaching 400.....
     
  4. Tad
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    Tad Boat Designer

    If you look at the DD forum you'll find some real fuel use and speed numbers. One fellow mentions a voyage coastwise off California in a DD38 at 6.4 knots average burning 1.3 gal/hr.....that's 27 HP.....quite a bit more than George's "computer" calculated 6.6HP......:eek:
     
  5. Tad
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    Tad Boat Designer

    Tom,

    Yep, the problem with general statements is they are often useless in particular cases......With boats one can always find exceptions to any rule.....

    On the "anything will plane" concept......:D

    Years ago in Maine we dropped a big V8 Crusader into a tiny narrow 28' round bottom lightweight lobsterboat.....with the idea of going racing......well, it planed all right...:eek:....oh my.....on it's side and completely out of control...thrilling but not workable.
     
  6. tom28571
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    tom28571 Senior Member

    I saw some scary stuff in one of the annual lobsterboat races. Over powering is the name of that game I guess. Several of the boats looked nearly out of control when hitting a wake or even nothing obvious. One went crazy with yawing and completely foundered. I think its probably caused by driving a highly warped bottom way past its limits and round chines probably do not help. At least some of my experiments point to that as a possibility.

    Speed skiffs are another case of racing something that is really not stable enough for that. Well NASCAR races trucks and I even remember seeing semi-trucks racing on TV once.
     
  7. Mik the stick
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    Mik the stick Senior Member

    Well I think I'm on the right track. Naval architects don't lie they ESTIMATE.

    A college tutor once said to me "Your theory (electrical) is fine, just remember that in practice it can go belly up very quickly";).
     
  8. tunnels

    tunnels Previous Member

    What makes for a planning hull !!
    a flatish shaped hull,
    lots and lots of power ,
    huge fuel tanks
    and a bottomless pit if money
    and thats just for starters :(
     

  9. Morro
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    Morro Junior Member

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