hook

Discussion in 'Boat Design' started by jerry cockrell, Jul 2, 2010.

  1. jerry cockrell
    Joined: Jul 2010
    Posts: 3
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    Location: minnesota

    jerry cockrell New Member

    hello, i have a 22 ft cuddy (which was born as a stern drive) when i chose it for my project boat i converted it to an outboard.
    im well pleased with it but for one thing. it had a hook aprox. 3/8" by 4 ft.
    i finnaly got it down to aprox .100 (a little under an 1/8")
    the reason it bugs me so bad is that my trim has no effect on the boat when on plane. im still pushing about 6 inches of water with the bow at w.o.t
    i am in the process now of trying to get the rest of the hook out, and im considering the idea of creating a rocker just ahead of the center of gravity.
    tech details, my center of gravity is 5 ft 8 inches from the transom (empty)
    and 6 ft even with the driver
    set back= 13 inches
    engine weight= 640 lbs (4.0 litre) v8 300 hp johnson
    i have the ability to create a rocker, the question is if i should? and if so how deep and how long.
    thanks in advance for any help you can give me for my pet project.
    currently top speed is 55 mph. i just want to be able to get some of the bow out of the water,
    jerry
     
  2. Easy Rider
    Joined: Oct 2009
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    Location: NW Washington State USA

    Easy Rider Senior Member

    Cuddy what? Picture? I'm quite sure the "hook" is not supposed to be there. What does "pushing" 6" of water mean? I'd say make the boat as straight as possible going fast (55 is fast). Forget the rocker. Even if you wanted to go 15 the rocker should be spread over at least half the hull.

    Easy Rider
     
  3. jerry cockrell
    Joined: Jul 2010
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    Location: minnesota

    jerry cockrell New Member

    hi, thanks for the reply. 22 ft cuddy cabin by sylvan.
    hook; it may be partialy the result of the roller trailer. but at least some of it was designed in. that is visible by checking the rivet lines on the sides down low about a foot and a half from the transom.
    pushing 6 inches of water at the bow, literally.
    if you took a line from the transom on thebottom of the boat all the way to the bow, the point at which the curve of the bow deviates from straight: that point is aprox 6 inches deep at w.o.t. which is currently 55 mph (gps)
    the transom is only 3 inches deep at the sides at w.o.t.
    when i finaly get the bow up out of the water the old beast should run in the mid 60s.
    at that time my fuel consumption should drop a little bit, (currently about 32 to 35 gal. per hr. (w.o.t.)
    if a straight is optimal i can do that.
    or: since im already stripped down to the bare hull (again) i could fiesably put a rocker spread over about half of the hull.
    its like this, ive made several boats perform in the past.
    ive been working on this one for almost 3 years.
    thanks , jerry
    p.s. by the way, my last project boat was a 19 foot conroy bowrider.
    when i finished it. it would do 0 to 62 mph in 7 seconds. very kool.
     
  4. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    You are apparently most interested in speed. Rocker is a no-no if speed is your aim. Get too much rocker and the boat may porpoise.

    You are flirting with disaster if the forefoot is plowing at 55 MPH. A quartering wave or wake can send your boat in unintended directions at 80 feet per second (50mph). I would make a wild guess that the 0.100" hook is less influential than weight distribution.

    Some of the Alaskan maniacs who do the annual river races, with all out racing machines, build deliberate hooks into to their rocket ships.
     

  5. jerry cockrell
    Joined: Jul 2010
    Posts: 3
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    Location: minnesota

    jerry cockrell New Member

    thanks very much for your insight. you are absolutely correct about the boat being extremely sensitive to water conditions/patterns.
    that is the real reason im doing all this work to fix it. my son and i were just nearly thrown out of it at top speed as we went by a power plant exhaust water outlet.
    ill shoot for a straight bottom. i have a set of adjustable planes to mount under the pods if i need them, in the event that porpoising becomes an issue
    speed; im really ony looking for 60 mph. 55 at present would suit me ok if i had a planing attitude (dry forefoot as you called it)
    pics, i dont really know how to post pics but i have a few vids and lots of pics of this whole arduous ordeal of a project.
    long term goal, when i finaly get this project complete il probably toss it and build my own boat from scratch
    jerry
     
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