Request your input on my design

Discussion in 'Boat Design' started by richardf, Jul 15, 2013.

  1. JSL
    Joined: Nov 2012
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    Location: Delta BC

    JSL Senior Member

    Before I got into the design business a very well known Naval Architect here in the PNW told me that design was 60% art, 35% engineering, and 5% luck. His designs are classics in the industry.
    I have used the Rabl method on over 50 metal hulls from 16' to 70'. It is not quite as accurate as the "mathematicians system" but is more user (and boat) friendly, gives better control, and has certainly been satisfactory for any of the many builders (professional and amateur) I have worked with.
    I can post the article if interested.
     
    Last edited: Jul 24, 2013
  2. richardf
    Joined: May 2013
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    Location: Michigan

    richardf Junior Member

    Please post the article.
    Richard
     
  3. tugboat

    tugboat Previous Member

    Hey from northern Great lakes area Ontario!

    - I would love to see exactly what you mean when you say "used the Rabl method..."
    I know of Rabl's backyard books but never heard of it.
    I guess it off to "google" then

    cheers!
     
  4. JSL
    Joined: Nov 2012
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    Location: Delta BC

    JSL Senior Member

    MultiConic Development

    Here is the article - low res. & hi-res . After you have done a few designs and built the hulls you will get a feel for the process and how each material (steel, aluminum, plywood, etc) behaves..... and how good you are!
    On some planing hulls there is often a transition from 'cylindrical' (aft) to 'conic' (for'd) and one area to watch out for is the bottom plate around station 3 (30% of LWL from the stem/LWL intersection). If the plate is laid down and there is a butt joint to be made in this area, the plate may want to take over and 'oilcan' and make life 'interesting'.
     

    Attached Files:

  5. richardf
    Joined: May 2013
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    Location: Michigan

    richardf Junior Member

    I just ordered Gerr's books from Amazon. Look out for more questions once I get into them. Thanks for a lot of good information coming from this thread (for me, anyway).
    Richard
     
  6. Leo Lazauskas
    Joined: Jan 2002
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    Location: Adelaide, South Australia

    Leo Lazauskas Senior Member

    Nice work,Wayne.
    And I like the bowls too!
     
  7. tunnels

    tunnels Previous Member

    that's some serous pony's on the back !!!
    Wonder when the next lot of even bigger motors will be rolled out and hit the water !!
    Gas turbine oooooooooh ! now that's a scary thought !!:eek::):D:p
     
  8. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    Years ago I made two models ( 1.2 metres maybe) of planing hulls, both were 20 degrees at the transom, the difference between the them was basically that one was a developed bottom shaped with thin ply, the other straight vee throughout made with thin strips. Other than that, basically the same dimensions and weight. Towing them behind a boat on a slight chop, the most noticeable difference was the developed bottom bucked and leapt rather more the other. I realise dynamic forces are amplified in a small model, but it made an impression on me, and convinced me the limitations imposed by having to be developable makes a difference in this type of boat, in a non-planing design probably not so much, or very little..
     
  9. dskira

    dskira Previous Member

    The one who told you that was not a naval architect, or was pulling your leg and you are so gullible that you wrote the quote here.
     
  10. richardf
    Joined: May 2013
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    Location: Michigan

    richardf Junior Member

    Are you a naval architect? Fron what college did you receive your degree?
     
  11. rasorinc
    Joined: Nov 2007
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    Location: OREGON

    rasorinc Senior Member

    richardf, `don't get testy when your challenged on this forum. It is really not meant to be personal so do not let the hair on your back stand up. We all need the knowledge of our various members to get our questions answered and were happy when those questions generate answers for us. Many here are much more knowledgable then I am in their fields but I can always hold my own in my field of knowledge. Relax and enjoy the learning experience. Stan Rasor
     
  12. El_Guero

    El_Guero Previous Member

    Would you explain the basics of the math involved?

    Or what would be a one sentence statement of what the goal is? Are we moving from a flat keel to a rounded keel? for example.

    Once I have a picture of where the math is supposed to go, it is easier for me to read someone else's numbers.

    Wayne
     
  13. HakimKlunker
    Joined: Aug 2009
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    Location: Thailand

    HakimKlunker Andreas der Juengere

    I would agree that you are limited in possible shapes.
    But that does not mean that it is an inferiour type of shape; I read that as an implication in your post.
    Look at the 'Fireball' class (as only one example) and see how they outperform many other 'undevelopped' boats.
     
  14. HakimKlunker
    Joined: Aug 2009
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    Location: Thailand

    HakimKlunker Andreas der Juengere

    You can go trigonometry if you need to involve mathematics.
    But actually it is a method to AVOID maths.
     

  15. El_Guero

    El_Guero Previous Member

    Hakim, I understand that.

    That is why I need a 'bridge' to help me see what they are saying. If it was straight trig, I would see that immediately.

    It is just they way my brain is wired ....
     
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