View Full Version : How to build a model from lines & offsets
11-01-2004, 12:26 PM
I would like a book title to give me more information about building a scale model. From John Gardner book "Wooden Boats to Build and Use" page 115 the Jonesporter Launch. I want to build a model of this boat. I guess it will need to be carved, the hull has a round bilge. I need more knowledge to do it right. Thank You.
Michael, if the plans provide a table of offsets and decent drawings, that's all you'll need. Scale down the measurements to something convenient like one inch equals one foot and loft the boat model size. Or, probably the easier way, if the plans include section line drawings, which is virtually always the case, they will probably be accurate enough to build a model from. Scale them to the size you want using a photo copier and build the model size station molds, line them up on a 'backbone' which is scaled from the profile drawing, and then plank it. I've built 3 hull models this way, one 22 inches long and the other two 29 inches long. Building a solid hull by carving from a block of wood may turn out to be much harder. The only way I've tried it is by first creating female staion molds cut out of cardboard and trying to get the carving to fit in them. There may be an easier way but I couldn't think of one.
11-01-2004, 01:53 PM
I second what JimD said - scaling plans is easy. Get an architect's scale and some paper, decide how big you want your model to be and go to it.
Two books on basic model constuction techniques are Boat Modeling With Dynamite Payson and Boat Modeling the Easy Way - both by Harold "Dynamite" Payson. These books will show you how to actually build the model once you've got the lines laid down to your chosen scale.
Another thought, after planking I fair with Elmer's Wood filler (or brand of choice) which cures hard enough and sands and paints very easily.
11-01-2004, 03:15 PM
Ralph, Walter J. Simmons has a book, "Lines, Lofting, and Half Models" $25. You can get it from him or from our host bookstore. A good book I think. I also have on that is a small book from one of the museums but can't remember which one. If Walters book is not the ticket I'll dig out the other one. try www.duck-trap.com (http://www.duck-trap.com)
11-01-2004, 03:17 PM
There is a good description in one of L.Francis Herreshoff's books. (Probably a lot of other places, too.) It's been decades since I read it, but I remember that he made section shapes from the body plan that he could hold up against the model to see how he was doing.
...and make the frames, stem, and transom out of thick enough stock that they can hold a thumb tack or small finishing nail that you can remove after gluing as you'll have to secure the planks while the glue dries and they will especially want to pop off at the ends where they're sprung the most...
11-01-2004, 05:23 PM
It is actually very easy. I have built lots of models from lines and offsets and will be happy to give you any pointers you need.
Basically I start by cutting out the back/centerplane of the model in 1/16" balsa sheet from the outline drawing. I then fiberglass that sheet of balsa to stiffen it up. Once that is done I use the rawings to cut out a set of frames. After glueing the the frames to the backplane, I plank the model using 1/16" x 3/16". When the model is planked I sand it reasonably fair and then fiberglass the entire model prior to fairing and painting.
This web site illustrates the step by step process with lots of pictures.
If you have questions about how to build a model just e-mail me. I am glad to help in any way.
Todd D http://www.todddunnmicroyachts.com/detail/cd_30-2.jpg
11-01-2004, 05:36 PM
I made a 1/2 model of the Jonesporter a few years ago.(cedar strips and hot glue) I converted all the english dimensions to metric and then scaled down from there.
11-01-2004, 06:04 PM
Nice work and site Todd!
11-01-2004, 07:40 PM
11-01-2004, 09:24 PM
Thanks. I try to build nice models. My next plan is to build a slightly larger "model", say around 17 feet ;)
11-02-2004, 12:43 PM
Another very good publication is one by the Maine Maritime Museum called "Half-Hull Modeling"
by David King. It addresses the history and proceedure for modeling and modeling only.
11-02-2004, 04:40 PM
Originally posted by Todd Dunn:
Thanks. I try to build nice models. My next plan is to build a slightly larger "model", say around 17 feet ;) Darn good try too. smile.gif Exqusite, in fact.
11-02-2004, 07:48 PM
I have used Excell for making mold section layouts for a model, and a friend has used Word. I prefer excell because once you have the offsets in a file you can recompute to any scale. Once the sections are created print out on your printer, glue the paper to wood and start cutting.
11-02-2004, 08:13 PM
Todd, that is excellent work! smile.gif smile.gif
Ken, I have always wondered how that is done in Excell. It took me forever to build a spreadsheet to do simple addition and subtraction. Can it be explained 'simply'??
11-02-2004, 08:22 PM
Can't give you a book title and I'm not sure what you want to do with the model. Noodling with cardboard will teach you a lot about "real" boatbuilding. A round bilge wouldn't be out of the question. This came from tracing the lines from a article in my favorite magazine. It's about twenty inches long.
11-04-2004, 10:09 PM
A comment about scaling plans. I convert all my drawings into a vector graphics form. Once that is done I can easily scale the drawings to any size I want. For the last several years I have been using CorelDraw to draw the lines and scale the drawings. I particularly like the option to work with layers in a single drawing. That makes it possible to add or remove detail very easily.
I also use vector drawings for all my component drawings, particularly when I make a working drawing for machining a steering pedestal, winch or some other component.
11-04-2004, 11:24 PM
Scaling by ruler or graphs is old school when you can measure the real length on the page and determine the enlargment required, ie. 150% or l57%, and go to any stationary shop with a good photocopier, dial in the enlargment and go! I will test one page and adjust +/- till I have a close representation. It use to be that the drawings could get a little distorted aroung the edges but if you keep the desired part in the center, in other words, dont get cheap and do it once when a couple of pages would be better, you will be fine. Yes some fine lines can become rather thick, but I just average it out.
I have been successful enlarging 600% in three stages. A lot less time than the labour intensive method.
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