Taking of lines

Discussion in 'Boat Design' started by Woobs, Aug 5, 2015.

  1. TANSL
    Joined: Sep 2011
    Posts: 7,039
    Likes: 569, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    How are you positioning the boat to measure, in the position 1 or 2?
     

    Attached Files:

  2. Woobs
    Joined: Jul 2015
    Posts: 44
    Likes: 5, Points: 0, Legacy Rep: 49
    Location: Newmarket, Ont

    Woobs Junior Member

    Thanks all!

    This boat spent almost 5 years inverted while I restored her. She's all finished and I get her wet regularly. So, I can't see me pulling the engine/drive out and flipping her unless I absolutely have to.

    I'm not going to rush in here and will study this some more. I have a laser level so, it may be time to learn how to use it :)

    The issue now will be finding a suitable place to do this that I can have for at least a week. My garage is totally unsuitable.
     

    Attached Files:

  3. Woobs
    Joined: Jul 2015
    Posts: 44
    Likes: 5, Points: 0, Legacy Rep: 49
    Location: Newmarket, Ont

    Woobs Junior Member

    I think I'll take her off the trailer (use boat dollies) and level the keel with the floor. (So, #2, I suppose)

    However, it might be easier with position 1... Truly, I believe a good portion of the keel and deck are parallel... but, I suppose we'll find out if that is true :)
     
  4. claydog
    Joined: Dec 2010
    Posts: 71
    Likes: 2, Points: 8, Legacy Rep: 69
    Location: michigan

    claydog Junior Member

    #1 would be better than #2, but personally I would set the boat up with the floor level and let the other lines fall were they may.



    Disclaimer; I have not used my laser method to capture lines on a boat, I have however used a version of this method with great success to make a symmetrically opposite duplicate of the driver side of full size automotive clay model.
     
  5. gonzo
    Joined: Aug 2002
    Posts: 15,934
    Likes: 1,286, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    The position is irrelevant as the lines are taken to a reference which is fixed. The measurements are then transcribed to the lofting or drafting board.
     
  6. TANSL
    Joined: Sep 2011
    Posts: 7,039
    Likes: 569, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    It is irrelevant or not but do not take the correct reference line can lead to further significant (relevant) problems. It seems that to think the best solution for what one wants to do is not a relevant activity for some people.
    Woobs, even irrelevant, think about what you need.
     
  7. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 494, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Lines are setup for two basic purposes: the first to preserve the shapes so repairs or new builds can be accurately made and the second to have a representation of the hull shape. There may not seem a distinction, but there is.

    Simply put some lines are much less accommodating to a new builder and essentially is a pretty picture. While other approaches to lines drawings make understanding what's going on with volume distribution and hull shapes easy to comprehend.

    Typically the profile drawing shows a common base line, which is paralleling the LWL. This represents the actual shapes, as the boat appears on the water, but can be difficult to read in the sectional drawing, as some of the lines may merge so much as to become muddy. In days of old, the base line was often following the "drag" of the keel, which greatly helps show the shapes in the sectionals, making it easier to loft them up full size.

    The 18th century sloop clearly shows the base line paralleling the LWL approach and the easily seen sectional shapes. None of the lines are merging enough to muddy up where they're going, so it's easy to pull offsets and templates.

    The Sultana drawing by Chapelle shows the baseline paralleling the keel's drag. Some of the sectional shapes are hard to define with this approach and because the sections are canted to reality, in regard to how the boat actually floats, difficult to tell what's really going on with these shapes, in terms of volume distribution.

    In powerboats this muddiness can become a real problem with a lines drawing, where the aft sections become so convoluted, you can't see much, without busting out separate sectional offsets and drawing each one separately.

    [​IMG]

    So, it's like I mentioned and the drawing depends on what you want these lines to do. If you want them to use comparatively, with other hulls of similar shape, select a baseline that parallels the LWL. You might get some muddiness on some hull shapes, but the shapes depicted will be representative of the boat in the water. If on the other hand, you just want a picture, on this particular hull, you might want to cant the baseline a bit so the sectional shapes are more defined visually.
     

    Attached Files:

  8. Woobs
    Joined: Jul 2015
    Posts: 44
    Likes: 5, Points: 0, Legacy Rep: 49
    Location: Newmarket, Ont

    Woobs Junior Member

    Now, look at the shape of the boat... I think it will be easiest to level the keel. I can probably sit it on blocks and be very close. Also, it is closest to the floor and easiest to measure. If I try level at the sheer I have to check 2 sides every time I adjust.

    Once set, all measurements will be relative to this position. Right?
     
  9. Woobs
    Joined: Jul 2015
    Posts: 44
    Likes: 5, Points: 0, Legacy Rep: 49
    Location: Newmarket, Ont

    Woobs Junior Member

    Since I'm not actually building a copy of this boat, I don't really need to analyze volume distribution. I'm no Engineer, Designer or Naval Architect so, I wouldn't dare try to produce plans to build from. Given that, I'm looking for a representation of the hull shape. As no drawings of any type are known to exist for this boat; this drawing will serve to record for posterity. Not that I wouldn't want plans you could build from.... I just don't think they are attainable with my resources.

    In the end, I'd like to produce drawings similar to those of the Donzi 16 (by W. Walters) below.
     

    Attached Files:

  10. TANSL
    Joined: Sep 2011
    Posts: 7,039
    Likes: 569, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    Now that we know what you want, you will allow me to make a recommendation: you observe the plane left of the two figures attached to your post. You can easily check for cross sections of the hull which, who knows why, are perpendicular to the waterline. As the water line use to be horizontal, you should put your boat so that its frames, or bulkheads, were perpendicular to a horizontal line which, as some have previously advised you, is the first thing you should materialize .
    Level the boat transversely as well and, to measure!
    On ships there is almost nothing simple, so, my friend, be wary of those who tell you that something is easy or irrelevant. Everything is simple if done wrong.
     
  11. gonzo
    Joined: Aug 2002
    Posts: 15,934
    Likes: 1,286, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    The reference line get replicated at the lofting or drafting board, therefore, it is irrelevant where it is. A curve can be used, if convenient.
     
  12. rasorinc
    Joined: Nov 2007
    Posts: 1,854
    Likes: 71, Points: 48, Legacy Rep: 896
    Location: OREGON

    rasorinc Senior Member

    I thought I read on this site a few years back about cameras that could photo a boat and then turn out a lines drawing???
     
  13. gonzo
    Joined: Aug 2002
    Posts: 15,934
    Likes: 1,286, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Yes, they take all the fun from drawing ;)
     
  14. TANSL
    Joined: Sep 2011
    Posts: 7,039
    Likes: 569, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    It is irrelevant if you just want to do a silly little drawing of the boat. When you want to do something serious, it is important to take a good baseline. Greatly simplifies subsequent work.
     

  15. Woobs
    Joined: Jul 2015
    Posts: 44
    Likes: 5, Points: 0, Legacy Rep: 49
    Location: Newmarket, Ont

    Woobs Junior Member

    Well, I'd hardly categorize this as a "silly little drawing" (but, thanks for trivializing my interests) as it will be the only known record of this design which has a rich history in this area. If I wanted a "silly little drawing" I'd commission an artist... or a photographer & IT specialist to manipulate the photo(s).

    Any technical drawing is a serious one. Some just have more, or less detail depending on the desired purpose. That said, I agree that a good baseline is important. Others may work a different way that suits them but, in the end it's what is on the paper that counts...If it all looks the same then, who cares how you got there?
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.