First Lines Plan - Advice Appreciated

Discussion in 'Boat Design' started by Owen, Mar 6, 2010.

  1. Owen
    Joined: Feb 2002
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    Location: University of Southampton

    Owen EX LIQUIDUS IN CONTEXTUS

    I am a Naval Art. undergraduate at the University of Southampton, England.

    For this semester's ship design project I have been tasked with drawing the lines plan of a 110m Cargo Hull.
    I have been influenced by the standard N.A. reference texts, i.e. Comstock et al., and believe the drawing is almost complete.

    I have attached the pdf file and welcome all those who are interested to take a look.

    Thus, I welcome reactions/comments with respect to these points,

    1. Does the numbering style of the waterlines correlate with accepted conventions? Does the high density of leader lines in the bow make it difficult to assess the bow shape? Given that the number and spacing of waterlines is fixed is there a way better present this?

    2. Should I label the deck in the profile and half-breadth view? Our design spec. set this as the bulkhead deck, would it improve clarity to label it as such?

    3. Are the hydrostatic and principle dimensions detailed enough? Should I add any other information.

    Otherwise, I would be happy to discuss my interpretation of a typical ship's lines plan.

    Regards from Academia,

    Owen D. Llewellyn
     

    Attached Files:

    Last edited: Mar 6, 2010
  2. jehardiman
    Joined: Aug 2004
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    jehardiman Senior Member

    1) If you think it looks too busy, delete every other WL lable. The lines plan only needs to show the general shape, as the lofters/CNC will be working from the offsets or the shape file.

    2) The profile should be of the sheer, including bulwarks, with the (underside of, usually) deck shown at the shell intersection. This is to ease plate layout.

    3) I would change the text to read LCB "aft midships" or the measurement to "fwd AP" vice using a negative. Though the lines and stations are laid out in the typical european style (stations aft), you have placed your measurement axis system forward-port-up in normal convention. Changing the text removes any possible confusion. Similary, I would change the text to "Displacement to LWL" or Displacement to 6.5m WL" as with normal loaded trim, you might not be that tonnage. Also check to make sure you mean TONS (2240 lbs) not TONNES (1,000kg)

    Otherwise I would suggest the following changes:

    Lable station "-2/11" as what it is, the Transom.

    You need to change the AP station or Transom station above the 8m wl because the plating is unfair. The full-hollow-full for stations 1/4-AP-Transom is poor design as it is expensive for no purpose.

    If the bilge radius is fixed, show that on the section dwg (edit: not plan but dwg is what I meant).

    Show the limit of the flat floors on the plan and any deadrise on the section.
     
    Last edited: Mar 6, 2010
  3. Joe Petrich
    Joined: Jun 2008
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    Location: PNW

    Joe Petrich Designer

    It's mostly a matter of style but I would place the waterline callouts in plan view on the other side of the hull so they do not cross centerline. I would also make the body plan the same scale as the other views, but perhaps this will make it unreadable. I agree that the transom would be very expensive to build as shown.
     
  4. Owen
    Joined: Feb 2002
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    Location: University of Southampton

    Owen EX LIQUIDUS IN CONTEXTUS

    Gentlemen, thank-you for your contributions.

    I will respond to each point in turn,

    1) Yes, I agree that the WL data must be re-organised. I will try moving it to the outboard side of the half-breath plan. Similarly, I thought I would try to label the odd WL AFT and the Even one's FWD.

    2) Got it! Thanks.

    3) Yes, two changes with solid rational, thank-you.

    Station -2/11 is placed 2m AFT of the AP, so is close to, but not quite the transom. Would the label (-57m) give a clearer indication, rather than an obscure fraction of the station spacing. Further, should I write down the station spacing as 11m in the title block?

    With regards to the fairing. Our professor dictated that the vessel must have a specific sectional area curve and for the propeller arch and transom curves to be coplanar. Of the few solutions that fit these requirements, this was the most reasonable. I debated in class the rational for having us create unreasonable Transom sections and was told the Matrix manipulation required to confirm that the curves were coplanar was a worthy exercise, even at the expense of NA convention.

    Yes, the bilge radius was fixed, should I use CAD conventions, i.e. R 1.5m, to label this?

    The plan is to be printed on ISO A3 sheets, and we were advised to use as much space as possible, hence the varying scale. I understand candidates lost marks for this criteria in the past.

    As a concluding remark, I realise I should have set the context of the exercise. It was to create and fair a lines plan using given form parameters, midship section, fineness coefficients, and thus paid no concessions to hyrdro-dynamics/performance/seakeeping, etc..

    Thank-you for your interest in this work, it is appreciated.
     

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

    jehardiman Senior Member

    The lines plan needs to show the actual transom, regardless if it fits some station spacing scheme. Sometimes (like with a curved and raked transom) it is necessary to show an imaginary station aft of the transom to ensure the lines are fair, but the actual transom needs to be shown. Generally station spacing is specified in the Offset table, there is no need to place them according to some Simpson's or Tchebycheff's rule, indeed, you can mix and match if you need to.

    " Our professor dictated that the vessel must have a specific sectional area curve..." This I don't understand, as sectional area curves are normally only specified for the submerged portion of the hull for powering reasons. Is there a volumemetric curve for cargo needs? Such as an aft container stack? In that case, it better to narrow the stern somewhat for powering, give it a large flare, and then knuckle the hullform above the waterline with more vertical sides to reduce shell weight and maximize hold volume. Flare aft in a container ship is wasted space.

    Yes, the typical callout is "Bilge radius XX.X Stations Y to Z". This gives the lofters something to work with unstead of guessing trying to fit the offsets.
     
    Last edited: Mar 7, 2010
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