No buttocks

[Don Case]

I downloaded the hi res images of the lines drawing of Discovery1789 from Wikimedia. There is a lot of info but there are no buttocks lines. Does that leave me dead in the water so to speak? I was thinking that I could use the sections and carve a half hull and pull the frame shapes off that but if there is an easier way

[druxey]

Buttock lines are seldom seen on contemporary draughts. If you have the knowledge, by using waterlines and station sections you can construct these yourself.

[Roger Pellett]

Two out of three plots, waterlines and body plan shapes plus bow and stern profiles, define the shape of the hull.  Modern naval architects add buttocks and diagonals to check the fairness of the hull.

 

Do you plan to redraw the lines?  Relying on the downloaded image without making a new drawing is unlikely to yield a set of frames that will produce a fair hull.

[Don Case]

Thanks you confirmed what I have discovered. While you guys were answering I figured out how to plot the buttock lines. Thinking in 3 dimensions is hard😃 My back was giving out while I was hunched over my workbench so I raised it a foot and now work standing up. I can see the need to redraw, those big blurry lines really spread out. If you're starting from the same blurry lines how do you produce a nice clean drawing? You're going to be guessing at the starting point anyway. Do you just hope it will average out?

[allanyed]

If you study the drafting articles here at MSW you will have everything you need to convert the images into your own CAD drawings.  Easiest way to start and to also correct distortions that most of the old drawings have is to insert the image into a new drawing page in your CAD program and extend or shrink whichever dimension, if either, is off a bit.  Most of the originals are 1:48 but you can enlarge the image so the length of the gundeck, which is easy to find in many, if not most, cases is actual size.   Trace the lines with straight lines, arcs and circles for the most part.   Once your drawing is complete, you can scale to whatever you want.  Keep in mind these were done by hand with pencil and/or pen so the lines do not have the same perfect edge as a line in you CAD program as you will see when you enlarge a section to a large extent.    When you blow up the image you will find lines that do not meet or go beyond the meeting point at times but such was the nature of drawing by hand.   This is a great way to learn about the construction of these ships and will no doubt bring on a host of additional questions.  Again, study the information here at MSW, it will answer most of your questions.

Allan

 

Edited January 25, 2021 by allanyed

[Don Case]

I'm not sure my old brain is up to learning a CAD program. If I was to try and do this by hand would I be gaining much? Especially considering shaky hands.

I've wondered about the accuracy I read about. Lets say you make your section lines exact and then make your frames as close as you can to those lines. Then you glue it all together. Now you grab a board with coarse sandpaper and start fairing. Depending on how all those factors come together I can imagine that you might have to sand 1/32-1/16" off some frames. Doesn't that kind of negate a lot of the work you put into perfecting the plans. Not trying to be a jerk, just an honest question🙂

[allanyed]

Lots of ways to skin the proverbial cat here Don.  You can certainly draw up each station  (what I think you are calling sections) by hand.  There were no easily affordable CAD programs 35 years ago and we managed somehow :>)     Shaky hands..... CAD may be actually be better for you.  As for an old brain, I was around 60 when I first gave it a try.  I am FFFFFAAAARRRR from being an expert but learned enough to enjoy using this tool.   

 

Back one step.   You mention making your frame as close to  the lines as possible.  Are you talking about framed build (POF) or bulkhead build (POB)?  If you want to build a framed model, keep in mind each frame is made up of anywhere from 7 to 12 pieces, a bulkhead being just one solid piece in most instances, thus my question.   

 

Allan 

 

[Don Case]

POF. I'm going to try lofting(?) my frames after I get the buttocks drawn in. I'll do one and see how it matches the stations(or between the stations). This is the body plan I have to work with. I don't think it's too bad except for station 0