boat hull curve lofting tutorials

Discussion in 'Education' started by barbarian, Jan 7, 2013.

  1. barbarian
    Joined: Aug 2012
    Posts: 21
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Albania

    barbarian Junior Member

    Im trying to learn how draft the curves for the hull of a boat. Im pretty skilled in hand drafting as well as computer. I have some simple books in boat building but unfortunately they do not explain the drafting part nor how the grid is build or how the curves are aligned the water lines with the other curves. Anybody have any step by step tutorials on hull lofting? any good book titles that go in detail in the drafting part and how the table of offsets is created
     
  2. davhill
    Joined: May 2012
    Posts: 20
    Likes: 3, Points: 0, Legacy Rep: 28
    Location: Massachusetts

    davhill Junior Member

    Some dedicated works on the topic ...
    A good intro: Lines, Lofting, and Half Models (Walter Simmons)
    More complex, very complete: Lofting (Allan Vaitses)
    Another good working manual: Mystic Seaport Boatshop Lofting Manual (Thomas)

    Many boatbuilding books have useful discussions, for instance: Building Small Boats (Greg Rossel) chapter 7. A classic is Boatbuilding (Chapelle) chapter 2, but modern writers (like Rossel) are more understandable.
     
    1 person likes this.
  3. jehardiman
    Joined: Aug 2004
    Posts: 3,211
    Likes: 669, Points: 113, Legacy Rep: 2040
    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Barbarian;

    As I read your question, you are not looking for how to loft an existing set of lines, but how the lines are determined in the first place...correct? See this thread for a short description of how to draw a lines plan from scratch.

    http://www.boatdesign.net/forums/boat-design/lines-plan-29882.html

    But remember, you don't just sit down and draw a set of lines...first you have to come up with a set of requirements which you desire to meet. Then you trade them off against each other as you develop the preliminary lines, as well as doing weight and moment study and propulsion design. A vessel must be designed synergisticly, it is not a chinese menu.
     
  4. barbarian
    Joined: Aug 2012
    Posts: 21
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Albania

    barbarian Junior Member

    yeah thats right I was trying to figure out how to draw the curves. I want to reconstruct classical galley ships. So I have an idea of dimensions and volume of the ships size number of rowers basic shape overall. I wanted to understand the technical aspects of the curve designing part. I went to a boat museum some time ago and the guy there gave me a hand out which explained how the hull is drafted up how the section lines water lines cut lines everything is lined up. So that what I was looking to understand in depth.
     
  5. rick gray
    Joined: Dec 2012
    Posts: 87
    Likes: 4, Points: 8, Legacy Rep: 30
    Location: port coquitlam B.C.

    rick gray Junior Member

    lofting

    the principle in lofting is to generate 3 views, front elevation(rear if needed,because lines curve in and overlap) side view(buttock lines lines representing slices at centerline or distances off c/l) and waterline sections( or lines a base line or at hieghts above base) when all three prove the spot you get a fair line.imagine a cube of 1 foot sguare, how divide and slice the cube in 1" slices in all 3 views ,now any 3d shape ,A ship etc. will be proved and can be faired. so any frame half breadth at a waterline has to match the waterline view you layed out and any buttock height at a frame line has to match the buttock lines layed out.cut an orange in 3 ways and reassemble parts to get an idea.any spot has a width, a height and a distance along length. GET A BOOK on lofting
     
    1 person likes this.
  6. barbarian
    Joined: Aug 2012
    Posts: 21
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Albania

    barbarian Junior Member

    I have a degree in Industrial Design. I work as mechanical engineers so I do know about drafting and the different views. and how the concept of lofting works but what I was looking to understand better is how to align the curves with one another for each view
     
  7. DCockey
    Joined: Oct 2009
    Posts: 5,071
    Likes: 550, Points: 113, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    There are numerous approaches to creating a hull shape:

    1) Carve a half model. Lines and offsets can then be "lifted" from the half model. Very commonly used in the 19th century. Nathanial Herreshoff designed hulls by carving half models.

    2) Draw sections, waterlines, buttocks, etc using curves and splines/battens. Iteration is usually needed to ensure that the lines are fair and will intersect properly. This method was widely used in the 19th century and was the primary method during the 20th century for most yacht and ship design.

    3) Use a "molding" system and create sections based on manipulation of master curves, arcs, etc. Typically a set of molds or frames would be designed and built, set up, and then battens and/or planks sprung around the molds or frames. Adustments are made as needed.

    4) Draw sections, waterlines, buttocks, etc in a 2D or 3D CAD system. Iteration is usually needed to ensure that the lines are fair and will intersect properly. Essentially the same method as 2) but in a different medium.

    5) Create and manipulate a virtual surface or surfaces in a 3D design system until the desired shape is obtained. Lines and offsets are obtained from the virtual surface as needed. This approach might be considered as the digital analog of the carving a half-model.
     
  8. DCockey
    Joined: Oct 2009
    Posts: 5,071
    Likes: 550, Points: 113, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    Are planning to work with paper on in CAD/Design software?

    If you are given a set of lines do you know how to check that the width of a section at the height of a waterline is the same as the width of the corresponding waterline curve at the corresponding section location?
     
  9. jehardiman
    Joined: Aug 2004
    Posts: 3,211
    Likes: 669, Points: 113, Legacy Rep: 2040
    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Here is a basic introductory text on the terms and layout of a hull form drawing. Really, drawing on a computer won't give a true set of lines because most of the hull shape for those vessels comes from the spring of the planking. Drawing with battens then digitizing would be a better thing.

    http://v5.books.elsevier.com/bookscat/samples/9780750649889/9780750649889.PDF

    The bigger question is how you go about the layout of a set of lines of a rowed galley. Most of those vessels were made by a shipwright that never used a set of lines. Generally there would be rules of thumbs or "master moulds" that would define the relationships for length, beam, depth of hold. The building method (i.e. tenion shell, caravel, lapstrake) and the placement of these benchmarks (in the literal sense) would form the lines based upon the spring of the planking. If you have a specific galley you want to build (i.e. bireme, trireme, pentacoster, hulc, longship, Mediterranean, etc) I may be able to point you to a relevent text to develop a hull shape.
     
    Last edited: Jan 11, 2013
  10. rick gray
    Joined: Dec 2012
    Posts: 87
    Likes: 4, Points: 8, Legacy Rep: 30
    Location: port coquitlam B.C.

    rick gray Junior Member

    How to align curves? i must be missing something? what do you mean? i am a retired ships plater/loftsman. i also did autocon. 1oth scale and ms dos quickpart. i think there is a $10,000 download available.splining generates curves.do a scale scrieve and pick up offsets for computer.you can make a scale model then.
     
  11. barbarian
    Joined: Aug 2012
    Posts: 21
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Albania

    barbarian Junior Member

    First of I appreciate everyone's input this is very very helpful to me. @ DCockey I was hoping to learn the traditional method of hand drafting Draw sections, waterlines, buttocks curves then going and working into Cad such as Alias or Soldiworks. From what I can tell is that the shape of a hull of ship must be able to crate buoyancy and cut through the water so principles in fluid dynamics must be applied. I dont know how to check for the width thing

    @jehardiman thanx for the link mate really really helpfull. I was hoping to build scale model of Mediterranean ships. Specifically illyrian Ships. the lembus type ship which was adopted by the romans, Pristis and the Liburna. I have some image reference and have a good idea of what the outside contour of the ship is and few features and details. I can send you pictures if you want

    @rick gray the 2D curves the sections, waterlines, buttocks curves represent the hull in 3D right so they must align and intersect properly and are in relation to one another.
     
  12. jehardiman
    Joined: Aug 2004
    Posts: 3,211
    Likes: 669, Points: 113, Legacy Rep: 2040
    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Get a copy of The Evolution of the Wooden Ship (by Basil Greenhill, 1988, ISBN 0-8160-2121) It will show you develop a set of lines based the hull model, construction method, and historical period (though it really focuses on the northern european tradition circa 1850-1900). It does have a fairly good discussion of greco-roman ship construction, mainly using the Yassi Ada wrecks.
     
    1 person likes this.
  13. barbarian
    Joined: Aug 2012
    Posts: 21
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Albania

    barbarian Junior Member

    I Appreciate it thanx for the book title!
     
  14. ancient kayaker
    Joined: Aug 2006
    Posts: 3,497
    Likes: 147, Points: 0, Legacy Rep: 2291
    Location: Alliston, Ontario, Canada

    ancient kayaker aka Terry Haines

    - are you planning models or full-sized re-creations?
     

  15. barbarian
    Joined: Aug 2012
    Posts: 21
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Albania

    barbarian Junior Member

    Scale Model for now but maybe in the future If I can get more people I will attempt a full scale.
     
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.