designing a fast rowboat

Discussion in 'Boat Design' started by nordvindcrew, Oct 13, 2006.

  1. El_Guero

    El_Guero Previous Member

    You might want somewhere to sit, rather than on top.

    :D

    I like it. My first thought was, "I do not like it." But, as I looked at it for a minute, I realized I was not seeing the softer elements. Once I began to look at the finer curves, I thought she will be a beauty.

    Work.

    But, what graceful lines.

    What build technique will you use?

    wayne
     
  2. EirikNorway
    Joined: May 2012
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    Location: Norway, Oslo

    EirikNorway Junior Member

    Hi

    I will use strips With glassfiber. Ive been shooting the strips in place with nails. Making the aplication of epoxy the most time consuming part of fastening the strips.
    The interior layout will have a bench aft and a deck fore, leaving room for the sliding seat rigg.

    Eirik
     
  3. Clinton B Chase
    Joined: Mar 2005
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    Location: Saco, ME

    Clinton B Chase Senior Member

    Eirik, why don't you build strip-composite. Cedar strips, bead and cove, glue with white glue, glass inside and out. Makes a lighter boat than strip with nails.
     
  4. EirikNorway
    Joined: May 2012
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    EirikNorway Junior Member

    Iteration

    http://www.flickr.com/photos/7682263@N02/sets/72157635298097046/

    Made a finer exit, and analyse drawings. What do one think of the deadrise of the mid section, its pretty steep but has a soft chine for stability.

    I have used pine strips with epoxy/filler and shot it in place on a boat im building now. Its pretty fast and the epoxy is very forgiving.

    Eirik
     
  5. Clinton B Chase
    Joined: Mar 2005
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    Clinton B Chase Senior Member

    Eirik looks pretty good. I just finished a sketch based on my successful Drake Rowboat. Are you going with a transom for aesthetic reasons?

    I wonder if the hollow in the midship section really helps in anyway...do you have a Cp you are shooting for? What displacement are you going for?
     
  6. DCockey
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    DCockey Senior Member

    Where are folks getting Cp targets from?
     
  7. Clinton B Chase
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    Clinton B Chase Senior Member

    My Cps come from basis of comparison to existing designs. The way I was taught is to choose a Cp and calculate MSA given target displacement and LWL. Then draw the midship section to hit the MSA.
     
  8. Leo Lazauskas
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    Leo Lazauskas Senior Member

    I agree with the comment about the section shape. A hollow just adds
    wetted area and makes the boat top heavy. Is there some secret property that
    I am over-looking?

    Also, designing to a specific Cp seems like a very crude method.
     
  9. DCockey
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    DCockey Senior Member

    Wave resistance of 5 hull shapes, same length waterline, same beam waterline, same Cp, same sectional form.
     

    Attached Files:

  10. Leo Lazauskas
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    Location: Adelaide, South Australia

    Leo Lazauskas Senior Member

    Thanks, David.
    Do they also have the same wetted surface area?
    Did you use Michlet or some other program?
     
  11. DCockey
    Joined: Oct 2009
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    DCockey Senior Member

    Michlet was used. Wetted area is the very close but not quite the same. Total resistance plot attached. (Different scale used for resistance.)

    Also, draft was adjusted to keep displacement constant. Proportions are typical of some of the boats discussed in this thread.
     

    Attached Files:

  12. Clinton B Chase
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    Clinton B Chase Senior Member

    What accounts for the big increase for R30 and W30?
     
  13. DCockey
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    DCockey Senior Member

    I'm not divulging everything yet. Trying to retain a competitive advantage for the designs I'm working on.
     
  14. El_Guero

    El_Guero Previous Member

    Then why did you bring it up .... ?

    :)
     

  15. DCockey
    Joined: Oct 2009
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    DCockey Senior Member

    To show that hull shape factors beyond length waterline, beam waterline, displacement, sectional form and prismatic coefficient can significantly affect wave resistance, at least for boats with the proportions discussed in this thread. Some folks might find that interesting. It implies that anyone designing a fast rowboat might want to investigate variations in hull shape beyond the list above.
     
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