Numbers

Discussion in 'Boat Design' started by Millrtme14, Feb 3, 2008.

  1. Millrtme14
    Joined: Jan 2008
    Posts: 6
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    Location: MD

    Millrtme14 Junior Member

    I have tweaked my homemade design a little more and gotten a little closer to the "target" boats displacement. Overall are these numbers fairly desirable for a sailboat? I am new to designing and I am currently readding up to figure out what everything means, but I would very much like to have a naval architect or a seasoned designer break down the numbers and let me know if any of them point out any downfalls. The boat was designed using Delftship using pictures as a refernce along with basic dimensions. Thank you very mcuh for your help.


    Design length 55.000 ft Midship location 27.500 ft
    Length over all 55.000 ft Relative water density 1.025
    Design beam 14.400 ft Mean shell thickness 0.0000 ft
    Beam over all 14.328 ft Appendage coefficient 1.0000
    Design draft 3.000 ft
    ________________________________________
    Volume properties Waterplane properties
    Displaced volume 487.26 ft3 Length on waterline 55.000 ft
    Displacement 13.919 tons Beam on waterline 11.452 ft
    Block coefficient 0.2051 Waterplane coefficient 0.5683
    Prismatic coefficient 0.6144 Waterplane center of floatation 22.155 ft
    Vert. prismatic coefficient 0.3609 Entrance angle 12.735 Degr.
    Wetted surface area 507.39 ft^2 Transverse moment of inertia 3624.7 ft^4
    Longitudinal center of buoyancy 25.357 ft Longitudinal moment of inertia 76821 ft^4
    Longitudinal center of buoyancy -3.897 %
    Vertical center of buoyancy 2.339 ft

    Midship properties Initial stability
    Midship section area 14.419 ft^2 Transverse metacentric height 9.778 ft
    Midship coefficient 0.3338 Longitudinal metacentric height 160.00 ft

    Lateral plane
    Lateral area 74.386 ft^2
    Longitudinal center of effort 30.112 ft
    Vertical center of effort 2.257 ft

    The following layer properties are calculated for both sides of the ship
    Layer Area Thickness Weight VCG LCG TCG
    ft^2 tons ft ft ft
    Layer 0 891.94 0.000 0.000 3.078 25.165 0.000 (CL)

    Sectional areas
    Location Area Location Area Location Area Location Area Location Area
    ft ft^2 ft ft^2 ft ft^2 ft ft^2 ft ft^2
    0.000 1.663 11.000 9.624 22.000 14.453 33.000 12.774 44.000 5.955
    2.750 3.419 13.750 11.224 24.750 14.671 35.750 11.407 46.750 4.166
    5.500 5.542 16.500 12.607 27.500 14.419 38.500 9.701 49.500 2.582
    8.250 7.704 19.250 13.744 30.250 13.763 41.250 7.838 52.250 1.226
     
  2. Gilbert
    Joined: Aug 2004
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    Location: Cathlamet, WA

    Gilbert Senior Member

    I don't see anything problematic with the numbers in particular. Although if you are aiming for a pure sailboat you might want the prismatic rather lower.
    Why not post the file and let us take a look at it? Or upload a bit map image of the lines drawing? You will get more useful input by doing that most likely.
     
  3. Millrtme14
    Joined: Jan 2008
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    Location: MD

    Millrtme14 Junior Member

    Here is what I have .jpeg wise. Just the 4 views from Delftship. As you can see it is somewhat VOR inspired, I guess more along the lines of what you might see in a modern IRC boat. Thanks again.
     

    Attached Files:

  4. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    This is the problem with the free and low cost design tools now available. It has you think you're designing a yacht when in fact you're just making a pretty picture.

    Without an solid understanding of yacht design, so that you can focus your tool efforts toward the design brief goals, you're just moving lines around on the screen.

    I'm not trying to offend you Millrtme14, you clearly have tried to design a big sailing dinghy, but there are several elements of the design that will encumber it's abilities in open water.

    What are the goals of the design? Target displacement, etc.?

    In other words, if you're looking for an IRC battle wagon, you may not want this hull to meet any of the serious competitors in deep water. Understanding why, is how you use the design tools to your (the hull's) best benefit. Without this knowledge, well . . .
     

  5. Millrtme14
    Joined: Jan 2008
    Posts: 6
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    Location: MD

    Millrtme14 Junior Member

    No offense taken and clearly I am not going to build a full size IRC boat simply from a couple hours on Delftship. I am reading up and trying to get a basic understanding of boat design, but my main goal is to build a scale RC version of a certain IRC boat that is out there sailing now. The "lines" I moved around on the screen were done so for the purpose of mimicking this said boat, purely from pictures. Now a fast RC boat would be nice, but I am just looking for a boat that will sail half decent. So far there are no scale races so I am going purely for visual representation. With that said, any comments are greatly appreciated. Thank you for your help.

    -Andrew
     
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