bow flare

Discussion in 'Boat Design' started by kapnD, Dec 24, 2011.

  1. rasorinc
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    rasorinc Senior Member

    Glen-L calls it a Bulbous Keel

    and reverse curve at the chine.
    Looks great and has an important fuction.
     
  2. viking north
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    viking north VINLAND

    Bulbous Keel ? thats a new term for me.
     
  3. rasorinc
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    rasorinc Senior Member

    BULBOUS FOREFOOT
    A convex entry at the keel/stem junction (as opposed to a sharp vee) incorporated to soften the ride. When used in conjunction with a reverse curve at the chine, it usually makes sheet materials impractical requiring other planking methods in the forward section.
    REVERSE CURVE
    A concave curve in the bottom at the chine. The usual purpose is to deflect spray.
     
  4. viking north
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    viking north VINLAND

    Thanks-Rasorinc-- got it --will toot the horn --in March as i pass thru Tenn. :)--Geo.
     
  5. whitepointer23

    whitepointer23 Previous Member

    all the hartley boats ny father home built were flared bows, double diagonal ply strips for the flare, pretty simple to do. i have owned flared and non flared boats, the non flared bows are just to wet for me. i am talking power boats not sail. this is my jet boat, you can't tell in the pic but it has a lot of flair in the bow and is very dry in most seas.
     

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  6. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Some of the wettest rides out there have flared bows, dryness in a planing hull is more a function of the rake of the buttock lines forward, below the chine. A cutaway forefoot is drier and more sure-footed with seas abaft of beam, all else being equal.
     
  7. Prismatic
    Joined: Mar 2013
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    Prismatic Junior Member

    Hi all...does anyone know where I can find this info or formulas that prove this statement. I am designing a boat and tend to agree with this but I am looking for verification. Thanks!
     
  8. Perm Stress
    Joined: Sep 2009
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    Perm Stress Senior Member

    take an IOR style design with 20degrees WL entry angle, 45 degree stem, flared bow and modern one with ~16 degree WL entry, vertical stem and little flare forward for a sail in same/similar conditions and see for yourself. :)
     
  9. tunnels

    tunnels Previous Member

    whats sort of speed you going to be doing ?? unless its over 60mph i wouldnt worry !
    at 50mph plus things are staring to happen with air pressure etc having an effect on lift of the bow , specially going into a head wind !! the boat gets a little light and flighty almost !! but it was never designed to ever go that fast !:eek:
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    Don't know about formulae, but you can get more "bog" running down-sea with a heavily flared bow, which can wash off a lot of speed, that will be less apparent in a similar boat, but without all the flare. Don't think there is much mystery in why, big flare= big waterline half angles, which at speed creates a lot of resistance. Running upwind much less of an issue.
     
  11. Prismatic
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    Prismatic Junior Member

    Thanks for the replies! So in 1-3' seas it takes less energy to slice through the waves than to lift on top....would this be true in all conditions? I'm new to boating and I am interested in designing a powerboat. Thanks!
     
  12. brian eiland
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    brian eiland Senior Member

  13. messabout
    Joined: Jan 2006
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    messabout Senior Member

    If this is not sufficiently arbitrary then there are the semantics to deal with. Sometime in the past, flair was differentiated from flam. If I can remember correctly, (which may be doubtful) flare was described as concave forward sections while flam was described as diverging sections that had no concavity. Or maybe it was the other way around. Only really old guys will recall the distinctions correctly.
     
  14. FAST FRED
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    FAST FRED Senior Member

    "It is not allways so easy to make mathematically developable surface to develop in the real world ."

    That's why God invented soft wood , chisels , rasps, files and sandpaper.

    If it was computer designed , it should be built . purchased and owned & operated by a computer!

    Esthetics counts in a boat , sadly there is no" Eye Candy" app yet.
     

  15. tunnels

    tunnels Previous Member

    We will survive !!

    we have survived for hundreds of years without computers so life will still go on when they pull the last plug as well . :eek:
     
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