Problem with Tables of Offsets

Discussion in 'Boat Design' started by Proflooney, Dec 26, 2016.

  1. Proflooney
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    Proflooney Junior Member

    My Problem I am used to stations being on the left, waterlines on the top listed plainly as feet, and then the offsets

    here they are listed differently and no matter what I do I cannot seem to get the correct sequence.

    is there anyone that knows enough about offset tables to help me figure out the correct sequences of numbers for the tables
     

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  2. TANSL
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    TANSL Senior Member

    The offsets table in your picture seems totally normal, with something that, indeed, would have to be interpreted, for example, section called "T". Could you show us some example of the table of offsets that you usually use?.
     
  3. Mr Efficiency
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    Mr Efficiency Senior Member

    T for transom ?
     
  4. PAR
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    PAR Yacht Designer/Builder

    I don't have much issue with these offsets either, though the station mold spacing is missing, it's likely available on the lines plan.
     
  5. Proflooney
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    Proflooney Junior Member

    the stations are 6'-6" apart with a 1/2 spacing in front and at the rear

    here is what I am used to seeing them laid out as
     

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  6. Proflooney
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    Proflooney Junior Member

    as you can see above its a simple layout with stations on left waterline heights on top and the offsets and makes it super easy to set up the curve generation tables for me.

    this other it has me lost as I am not used to seeing them laid out the way they are.

    here is the full line sheet http://www.proflooney.net/hullines-01.rar
     
  7. Heimfried
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    Heimfried Senior Member

    The offset table in post #5 shows a very small frame distance, maybe one inch or so. So you can create a curved line which simply consists of small pices of straight lines. If I understand this right: is the much larger distance in the offset table (6' 6", post #1) the problem? (If you put the 6 feet long pieces of straight lines together, it will produce a broken line, not a fair line.)
     
  8. Proflooney
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    Proflooney Junior Member

    No my problem is I am trying to make text files from offsets for importing into my CAD program and don't understand how to read the offset table the way they have it set up compared to the one above for the Fletcher where it is laid out easy for me to understand. I am new to all this boat stuff so

    trying to learn how they have the different styles set up
     
  9. TANSL
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    TANSL Senior Member

    If in the table of post # 1, you change the rows by columns is likely to get you to understand.
     
  10. Proflooney
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    Proflooney Junior Member

    well the othre problem I am having is it is isting the waterline names but I cannot find the dimensions for the waterlines
     
  11. Heimfried
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    Heimfried Senior Member

    The sketch below shows a boat placed in an cartesian coordinante system.

    The system defines three principal planes: the x-y plane (base plane, horizontally, parallel to the construction/design waterline), the x-z plane (center plane = plane of symmetry, vertically) and the y-z plane (vertically, all frames or stations are located in planes parallel to the y-z plane).

    Each offset value is the distance between one of the principal planes and the particular point of the hull (allways measured perpendicular to the reference plane).

    The drawing of the BCMBoat tells you that the waterline No 3 B is in a plane 3' above the base plane (z = 36") and parallel to it. And the value of half bread at station 2 is "1 - 3 - 4" so y = 15.5". Station 2 is located 2 times 6'-6" from y, z plane so x = 156" .

    The buttocks are located in planes parallel to the center plane and the drawing says with a distance of 2', 4' and 6'.

    The rabbet is the line along the keel where the bottom planks join the keel.
     

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  12. Proflooney
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    Proflooney Junior Member

    yes I see the waterline dims now however there are 3 dimensions missing for the waterlines 3A 4 5A
     
  13. Heimfried
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    Heimfried Senior Member

    Look at the drawing (body plan, top left). Stations are numbered and the station 5 shows the same half bread at sheer and waterlines 5 A, 4 A, 3 A.

    So the value of this offsets are the same than the value given a few lines above at the same station.
     
  14. Proflooney
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    Proflooney Junior Member

    so are you saying that the waterline height of 3A 4 and 5A has the same 1' spacing as the lower waterlines?

    ok I just got off work so going to try and redraw my excel file and change all the data locations around to match the way I am used to seeing on the Fletcher drawings and see if it makes more sense to me. I really appreciate you guys help and patience I just want to be sure I understand everything so that the next time I can do it without any problems. hehe wished it was as plain and simple as the fletcher layout
     

  15. Proflooney
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    Proflooney Junior Member

    well I rearranged them and they are sort of working out. it will take a lot of fudging to get them correct though
     

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