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Redshirt

How to deal with badly drawn plans?

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Redshirt   

Hello,

im trying to convert a newly purchased boat plan into cad but the apparent lack of accuracy drives me nuts. For example, neither are the station lines on the sheer plan in a 90 degrees angle to the reference line nor are the reference/ keel line and the waterlines in any way or shape paralel (which they usualy should). Trying to get one straight usualy offsets the other by a milimetre or more. I honestly don't quite know what to do except of burning the whole thing, can you give me any advise please? :)

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NenadM   

My son, who knows all Cad and cad-like software, shows me how to, but I was not satisfied, so I put raster as first layer in Adobe Illustrator, and in next layers draw my own vector drawings over. Slow, but results are fine for me

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Redshirt   

Are the original plans paper or a file? Which ship/boat? I can probably help with more info. Can you post a jpg of the plan?

 

The original plans are on paper. It's the barque catalane from the AAMM. The lines i added are perfectly aligned to the reference line/keelline at the bottom.

After some frustration and coming to the ultimate decision that 35bucks in paper shouldn't be burned i tried to align all other lines to the keelline and therefore get some consistency (drafting the middleframe worked more or less) but im not certain if this is the right approach.

 

*Edit* The example is obviously not a cad file, i just wanted to make my problems with the various lines on the original visible which have to be solved before i can convert the plan with autocad.

post-13321-0-19621800-1479159439_thumb.jpg

Edited by Redshirt
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jud   

Probably redraw using a grid for the reference and known distances you can glean from the drawings. I would start with the cross sections at the station lines first. When using a 2D cad program your Y coordinate will be the Z component later so work in the NE quadrant of your grid so all coordinates will be positive. When you get done, your new drawing if created using full scale numbers can printed at any scale you need. I'm doing something similar but took my cad into a surveying software package that will create contour lines. Had a power serge and computer needs some professional help before I can finish. The contour idea I am beginning to wonder if it is worth the trouble, an inexpensive 3 D program may be the wiser choice. You can fuss and rotate, re-scale, stretch or whatever and always wonder, redraw it.

jud

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The view that you shown includes water lines drawn parallel to the keel, station lines perpendicular to the keel and buttocks. Assuming that you have at least one more view (a plan view or a body plan) you have sufficient information to reconstruct a lines plan.

 

Start by preparing a table of offsets- x,y,z coordinates measured from the centerline for water lines and base lines for buttocks. Then plot them and pass curves through them. Whether by hand as I prefer to do or by CAD the process is the same. Your body plan (frame shapes) may be plotted from your other two views. Your curves may not pass exactly through all points and here is where some judgement on your part is required to produce "fair" curves with intersections that match exactly in all views.

 

Keep in mind that a definitive lines drawing that exactly portrays the shape of a known vessel is an illusion. Five naval architects making five lines drawings from the same table of offsets will produce five slightly different drawings because of the fairing process described above. The important thing is to make a drawing that accurately portrays the vessel's characteristics.

 

Roger

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Redshirt   

Thanks for the answers! Im not completely certain if im on the right track but the few frames i have managed to loft so far look promising.

Once i have a few more together i can check if it all fits. I have added an example frame.

post-13321-0-57656600-1479561514_thumb.jpg

Edited by Redshirt
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Redshirt   

Does your CAD have a 3D capability?

It's a student version of autocad 2014 so i believe it has but truth to be told, i barely manage to understand it's 2dimensional capabilities :D

My plan to check if im doing right is to measure the frames's outer lines at one, two and three centimeters and basicaly recreate a simple half breath plan. If the resulting waterlines are halfway harmonous then all should be well.

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If you can used the 3D, lay out the frames in position, and draw (in DesignCAD) a curved line along them at a fixed height. If the frames are correct, the line should be smooth in all directions, if a frame is out of line, draw the curve skipping it, and see where the correct point should be.

 

Below is, hopefully, an example. Why do this rather than a physical model? I can scale this to any one desired, and after I do I can used the parallel function to put in the lines taking account of the hull sheeting thickness I will be using.

 

Picture 1: The 3D frames with a waterline drawn. Note that the lines run along each other, except at the bow area frames.

 

Picture 2: A top side view: Note where the lines diverge.

 

Picture 3: A close up of the areas. The blue and red lines where the first and second attempt at laying the lines. Note how they bulge at the second and third frames, from the right. The green line is after I redrew those frames, with the corrected distance from the keel at that waterline. Here doing a model would be close enough for you to get an idea, but look at the next shot.

 

Picture 4; The before frame drawing of the hull lines. Note where frame 28 goes into the curve on one line and comes out on another line, and they don’t meet in the middle!

 

Picture 5: The before and after hull lines. The fore frames line up fairly well, but look at the aft frames! The original drawing was not even close!! The waterlines were run as in the previous pictures, from the transom to the stem, with a lot of iterations in between.

post-10090-0-05612600-1479565350_thumb.jpg

post-10090-0-01804300-1479565351_thumb.jpg

post-10090-0-80545700-1479565351_thumb.jpg

post-10090-0-67993100-1479566530_thumb.jpg

post-10090-0-45411700-1479566532_thumb.jpg

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druxey   

Whether manually drafting or on computer, never completely trust anyone else's draughts! There is always at least some re-fairing required, I've found. That example thlbaultron has posted is not that unusual. A proof diagonal is an excellent way to check fairness.

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Don9of11   

Most likely you are dealing with a copy of a copy of a copy and as such nothing is likely parallel or straight. I found the best thing you can do is establish your perpendiculars, the correct length, breadth and depth of your ship and scale your plans to fit as best you can to those parameters. You'll then need to make some assumptions and educated guesses, create you own water lines and diagonals and make the best of it. In the end your plans will be fair and workable.

 

Warning... with CAD there is a danger of wanting make everything supper accurate and super fair. Little deviations here and there can slow your work down to a crawl and drive you mad...lol.

Edited by Don9of11
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Posted (edited)

Hello All,

 

I am having a different problem.  For my current build - an extensive modification of Heller's Soleil Royal - I have been hand-drawing a scale field, or outline that matches the moulded profile of the kit's lower hull and upper bulwarks, which I will be using to save the time of a full scratch-build.

 

I sketched in one, each, of various repeating elements and a few specific ornamental details that were easier to draw by hand, in order to match the kit parameters.  On the advice of several members, here, I intended to digitize the pencil drawing and import it into Corel Draw, where I could trace over what was there, and add in all of the other missing details.  Ultimately, the objective is just to see what all of my additions and subtractions will look like in relation to each other, and to make it easier to layout the complicated frieze of the upper bulwarks, which would be a nightmare to do by hand.

 

Today, I digitized the paper drawing onto a flash drive in JPEG, PDF and PNG file formats.  Here is my hand-drawn plan in PDF format. For whatever reason, the site would not allow me to upload the JPEG drawing, here, and I don't even know what a PNG file is, but I was able to upload the PDF:

 

20170102130746616.pdf

 

Everything was going perfectly well until I came home tonight, ready to download Corel 7, only to realize that most early versions of Corel are not compatible with Mac computers.  Corel makes a very current CAD software that is Mac compatibile, but I'm not sure I need CAD software for what I'm doing.  I'm not lofting frames, or in any way trying to create a three-dimensional hull shape.  I just need a compatible 2D drawing software that will allow me to import, re-trace and manipulate the various ornamental elements that make up the ship's decoration.  I'll also be dropping the main and fore channels down to the upper, or main deck and will need to draw in the mast locations and layout the shrouds, so as not to interfere with the guns.  This drafting exercise is really just about laying things out so that I can be sure that everything lines up nicely before I start cutting things away.

 

Not long ago, I updated my OS to 10.11.6, El Capitan.  I'm a complete novice to computer drafting of any kind and am looking for something that is relatively easy to learn and use.  I'm frankly overwhelmed by the volume of drafting software, which seems more sophisticated than what I need.  All suggestions are welcome.

 

Thanks,

 

Marc

Edited by Hubac's Historian

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Posted (edited)

Alright, so I spent the evening initiating myself into the world of bitmap conversions into vector drawings, via line tracing function of various software packages, as demonstrated in a number of tutorial videos on Youtube.

 

Most software packages I looked at are Windows based, however, Adobe Illustrator is Mac compatible and disc software for Illustrator 9 is still available on Amazon for about $70, used, plus shipping.  My layman's understanding of this is that I could use something like Adobe Illustrator (largely ignoring 90%, or likely more, of the software's capability), to import my JPEG, or my PDF file format, into a new document.  From there, I can apply specific formats within the Image Trace tool bar, perhaps "line art," to automatically trace my ship image into a vector based, and grouped image.  From there, I can ungroup the image, and select specific groups for copy and paste, such as my various gun port sizes/styles, and then place them where I want them.  I can then import artwork for the quarter galleries, and various elements of the stern, and repeat the image tracing procedure.  Also, by unlocking the image, I can manipulate lines within a grouping to better suit my purposes and design intent.

 

So, assuming that's the basic gist of what I need to do, here, is Adobe a workable platform for the complete novice, or would I be better served finding something more basic?

 

I am still very uncertain, for example, how importing what is a relatively large drawing will appear in the Adobe active screen.  In all of the tutorials of various imported imagery and artwork, the graphic artist is shown corner dragging the image after import, generally, to increase it's size. However, for something large, would I first have to reduce it's scale to, say, 50% just so that I could work on large continuous details, like the wales, without having to break the image into a series of tiles that are then stitched back together later?  Does anyone use Adobe for their ship modeling design purposes?

 

I'm also curious as to how detailed the auto line-tracing functions are, with consideration to the many intricate filigree details of a baroque warship like SR.  If it is going to be necessary for me to go in and hand trace the stern gallery railings, for example, with a pen feature - with all of the attendant curves and reverse curves and mouldings, and etc - then it seems like hand-drawing and scaling would actually be faster, if equally frustrating.  Or, perhaps it's easy to do that, once you get the hang of it.  Is the trick to increase the scale and select, say a stern railing, from within the larger scan of Berain's stern schematic, for example, so that the railing is large enough for the auto-trace feature to pick out the intricacies of the design?  No experience = no clue.

 

Any input into these matters is greatly appreciated.

 

All the best,

 

Marc

Edited by Hubac's Historian

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Don9of11   

I'm not that familiar with Adobe Illustrator but as with any software there is a learning curve. It might be best to work on something simple until you learn where the tools are that you will need. As far as the file size and depending on how large the image or pdf might be, you could import small sections, draw them and slowly piece your drawing together.

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Stop!! For all intents and purposes, NO, tracing software is usable for drafting! None! Later today I'll show you an example, I have to go out for the day now.

 

The only viable way to go from JPG, PDF, etc. is to import the drawing and trace over it.

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Chuck   

You cant use auto trace...its just not accurate.  It also creates too many nodes in your lines.  Unfortunately there are no shortcuts and these "quick-fix" auto functions are just a way to do the job quickly and rather sloppily.  The only way you will be able to really do an accurate job is to import the image and trace over it while making corrections yourself.  Then as Druxey said, use diagonals and waterlines to fair and correct your traced lines.   It is a very time-consuming process but its the only way you will be sure its correct before you start making sawdust.

 

26ftlaunchsheetonehalf.jpg

 

I usually import an image and scale it to whatever the scale is I am working on...say 1:48.  But others find it easier to make the drawing full size so they can use the real measurements from Steele or a builders contract.  I use Corel Draw X8.  It works great and once you become proficient with using the dozen or so tools and functions needed it goes well.  You can use small tricks and methods to speed up the process.  I have taught several people over the phone how to use CD and in person.  I can usually get them to the point where they can work on their own with good results in just a few hours.  But they must understand lofting and fairing and ship design before they start using the software or the lack of architectural knowledge usually does them in.  Its easy enough to learn the software....much more difficult and time consuming to learn and understand how draft frames and proof out and fair your lines, along with adding all of those important details not shown on an original draft or simple plan original.

 

In the image posted above for example, you can see the original draft I will begin drafting and tracing over.  Also added to the workspace is an image of a similar contemporary model.  This is also scaled up to the same size as the draft.  Rather than flip back and forth to a photo on a different file or on paper, having the photo right above my work is an excellent and convenient reference.  I can quickly examine the contemporary model for features not shown on the draft or incorporate and design my parts to mimic those on the model.  For example, I can quickly use the model to design the joints between the stem and keel to closely mirror that models construction because its right above my workspace and not shown on the draft.

 

I usually have many more draft copies and photos in my workspace than shown here but this is how I work up a set of plans....once at a pont to fair the frames or correct inaccuracies in the draft I can hide those images while I create my own half-breadth plan or whatever third view I need to prove out my lines.   I use waterlines and diagonals to correct my frames while creating my own Half breadth view from the body plan and sheer plan I traced.  

 

Chuck

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As an example, I took a section of a plan showing the drawing imported as a graphic, and the traced results. (Yes a publicly distributed plan). The drawing shown is fairly course, I normally scan the plans in at 300DPI.

 

post-10090-0-88060700-1485473363_thumb.jpg

 

post-10090-0-64400300-1485473379_thumb.jpg

 

As you can see, the traced drawing is not in any case, in any way useful. This is the type of result any of the Tracing programs, free or purchased, will give you.

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russ   

I have been using CAD for about 10 years. I spent years before that drawing by hand, using pencil and vellum. While CAD allows for a neater and more accurate drawing, there is no substitute the hard work of fairing. I use waterlines, buttock lines, and diagonals to make sure that the hull is faired. It is a tedious process of going back and forth from body sections to sheer profile to half breadth, over and over, checking waterlines, buttocks, and diagonals. Move a little here, move a little there, go back and recheck, re-measure, look at the lines, and then when you are really certain that it all looks good, save and walk away, then come back tomorrow and check it again.

 

One book that I found very useful was Howard Chapelle's Boatbuilding. One chapter takes you through the layout and lofting, step by step of a small sailing craft. I also got a lot from reading Underhill's Plank on Frame Models volume 1. There are other books out there, but those are two of my favorites.

 

Russ

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After I get my initial frames done I lay them out in 3D and check the flow of the lines. I can't show an example, my main computer power supply died, and it has most of my files on it.

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russ   

Ron:

I guess I took what I did on a drafting board (self taught draftsman) and began doing it in the CAD program. I have not gotten into 3D, although it sounds fascinating. I think the 2D three view fairing process is something in my comfort zone.

 

Russ

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druxey   

Not wanting to put you off, Gemma, but there's an awful lot to learn about naval architecture! One article that is helpful in basics was published many years ago in Model Shipwright. No's 22, 23. I'm PM'ing you information.

Edited by druxey
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Mark P   

Hi Gemma;

 

Speaking of Model Shipwright,  David White wrote and illustrated a series of articles on understanding ships' draughts, and the construction of wooden ships.  These started in issue 46,  and the two subjects alternated through succeeding issues well into the 60s.  Unfortunately,  the series ended without being completed;  nobody knows why.  But what was published covered most topics.

 

They are mostly about the 18th century,  and explain so much,  so clearly,  that if you can get access to a set,  or these issues,  it is well worth it. 

 

I refer back to mine regularly.

 

All the best,

 

Mark P

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Here is an example of a 3D drawing of a boat I am doing. The plans showed the frames forward of the break fairly accurately, but the drawings of the aft frames were garbage.  By drawing everything in 3D I was able to work down to these final lines, by taking what accurate data I could find in other sections of the plans, and adjusting the aft frames over several iterations.

 

post-10090-0-22075300-1485619197_thumb.jpg

 

By doing this I can also readily see that all the lines are fair in all 3 projections.

 

I used a function of my CAD that draws a curve between several points. If all my data is good I get smooth lines. If not, I can see what points are out of line. Then I redraw the line, skipping the bad point(s). Now if the lines is good, I can take measurements, and redraw the frame(s) with the new data.

 

I can also select each window, and make it full screen, to see finer detail.

 

post-10090-0-68686800-1485619197_thumb.jpg

 

post-10090-0-12053900-1485619198_thumb.jpg

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Kishmul   

In my experience (limited, but extending to ships, horse-drawn vehicles, boxes and doll's houses) it is rare to find a set of plans that are 100% accurate.

To avoid frustration in the workshop (and the creation of large amounts of interestingly-shaped but expensive firewood) I "build" the model in 3D CAD in advance. This is not devoid of problems. CAD can be too accurate! That irritating gap that you have spotted and zoomed in to inspect is 1/512 of an inch wide, glue will fill that. Using the array function to place three portholes equally across a ten inch bulkhead creates an issue. Mixing units is possible and may be of use - buying rather than turning two hundred stanchions is a good notion, but if they are sold in mm and you are working in inches.......

To overcome this, I set the precision in CAD to that which I might reasonably attain in the workshop- for wood 1/64".

Even using this method, and checking wood dimensions as I go, planked hulls always require a final sanding to look "right".

I appreciate the dilemma when plans appear way off but many are xth generation copies of hand-drawn lines.

Imagine the problem of lifting lines from a 1:48 paper plan to create a full-size vessel with a keel in excess of one hundred feet.

CAD is an increasingly useful tool, fairing is still essential.

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Yes, the accuracy of CAD can be to distracting, sometimes. I draw my plans out full size, then reduce them for printing. I have to keep reminding my self, that no one built a wooden ship to 0.001 inch accuracy!

 

I leave the CAD set at 0.001", just because I do make some drawings that need it, and I'm sure I would forget to change it back and forth.

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mtaylor   

Gemma,

 

To get you started..  have a look at the database of articles here:  http://modelshipworldforum.com/ship-modeling-articles-and-downloads.php   The Plans and Research area has articles on lines drawings (and how to read them) and some CAD tutorials.

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