Table of offsets measurement

Discussion in 'Boat Design' started by NickNate, Mar 3, 2019.

  1. NickNate
    Joined: Mar 2019
    Posts: 1
    Likes: 0, Points: 1
    Location: Rotterdam

    NickNate New Member

    Hello all,

    Iam struggling to understand the offset table and need few clarifications as I am new to ship design

    I understood offset data has two tables

    1.Half breadth- the width of the waterline at each station measured from the centreline.

    2.Height above baseline- the height of each buttock above the datum line.

    I just don’t understand how to meaure Main deck side/ Main deck center and keel for the height above base line table.

    Im measuring the vertical distance of each station at interaction with buttock line. Please help me out.

    Body plan and offset table attached as JPEG file.
    lines plan attached as PDF.
    Awaiting feedback.

    Attached Files:

  2. nzboy
    Joined: Apr 2011
    Posts: 154
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    Location: nz

    nzboy Senior Member

    I haven't got time for a long answer. Imagine you are building this boat upside down it will then make sense
  3. nzboy
    Joined: Apr 2011
    Posts: 154
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    Location: nz

    nzboy Senior Member

    Sorry for the first post Im Back .The boat has 3 decks the main deck is 4.7 above base line the other 2 decks follow waterlines so no need for separate table
    The main deck has a 75mm camber because it sheds water

  4. jehardiman
    Joined: Aug 2004
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    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    As far as the keel goes, notice from the lines plan that from station 9 aft, the vessel has a flat plate keel. Using the table of Offsets this keel is 550mm wide (2x275) at BL at station 8 1/2, 800mm (2x400)at BL at station 8, and 800mm (2x400) at 1290mm above BL at station 1.
    As for the deck, NZboy is correct that the camber is the reason difference between the heights of the main deck at edge and centerline. However, there is a development error in the lines and offsets though, as the deck edge does not increase fwd as it should to maintain constant camber and there is actually no "deck edge" at station 10 1/4. Additionally, there are no offsets for the skeg. A good yard would correct these errors in the bid reply and returned as built lines.
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