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Extreme Clipper Witch of the Wave CAD

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Posted (edited)

Started work on a new project, the extreme clipper Witch of the Wave, built in 1851. She was designed and built by George Reynes of Portsmouth, NH.  She was originally owned by Glidden & Williams of Boston. Oddly enough, Gerorge Reynes son George Jr also built a packet freighter by the same name in 1856 in the same yard his father built this one in, so there is the possibility to get confused.

 

Witch of the Wave was quite long lived for an extreme clipper, sailing for at least 34 years. She set only one record, her 1855 passage from Calcutta, India to Boston, MA in 102 days.  She was quite beautiful even by standards of the day. A great deal of attention had been paid to the details of her workmanship and the quality of her fittings.  Her cabins were fitted out with rare woods of curious workmanship and expensive furnishings.  She had a library of over 100 books. Her figurehead was that of a beautiful woman holding aloft a scarf as she glides across the waves, with gilded branches and leaves stretching out behind her that grow to wrap around the hawse holes. She also had occuli, painted eyes on each side of her bowspirit commonly found on ships involved in the tea trade.

 

This log isn't intended to be anything but a log of how I do stuff.  Others do stuff differently and use different tools and concepts to do them. I'm not saying they aren't right, or that my ideas are better than theirs.  I'm only trying to show how I go about it.  I've worked in SolidWorks professionally since about 2006 and have done some WWII era warship models for Dragon Models and some CAD models of airframes for a company that restores WWII era fighter aircraft. So I'm posting this with the idea that you guys might be interested in how I do things.  The quid pro quo is that I am hoping you guys can share your knowledge about ships where I am lacking, and I have been able to ask a few things in the forum already, for which I'm grateful.  That said, I am hoping this doesn't come across as me being stuck up about how I do things or that I feel superior to others in my skills and knowledge-base.  I do things my way and steal ideas from everyone else when I don't know how to do something. You might notice that EdT's work on Young America is something I consider highly influential.  

 

This is where I started, research-wise. This was the first hard data I found on WotW. It comes from The Search for Speed Under Sail; 1700-1855 by Howard I. Chappelle. The book is 10" tall x 8" wide so unfolded this layout was 10" x 16", a pretty decent size to work with for a scan. Fortunately I happen to have a large format flatbed scanner which can do 11" x 17" at 12,000 DPI.

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The resulting image was 18528 x 12408 pixels. I cropped a part of it here for you to imagine how large the full size image (zoom for effect). Needless to say it would be a little unwieldy in this format so I had some work to do on it. Here you see the occuli and her figurehead.

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The first problem is that the plan and profile images were split on two pages.  Fortunately the image didn't go down into the gutter of the spine so I had nice clean edges to work with. In Photoshop I cut out pieces of the image and pasted them into a new document.  I then lined them up using the grid and rotate layer command. Here is the profile image done. The processes I'm describing were done for all images, I'm just showing a couple quick reference images in order to save time and space.  This is  apretty lengthy process by itself and should probably have it's own discussion.

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The next part was a little more involved. There was minor warping all over the image.  Fortunately there were tons of grid lines that I knew should be straight.  I had to use the warp transform tool on the parts to get them into some semblance of straight and true lines. Needless to say this wasn't easy and took me about an hour for each view. The fore/aft view wasn't as hard because I didn't have to stitch two halves together, but it still got straightened up. Here is the plan view done.

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Next I used the sketch picture tool under sketch tools in SolidWorks to insert the resulting images into a new part.  I added relevant geometry and used the dimensions I knew to scale the image up to the proper size.  I found out that the frame stations were on 32" centers which did not diminish near the ends. I then added in more geometry for the individual frame stations.

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Next I created a new sketch on the midship plane and added the hull lines and some waterline geometry.

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And after that the plan view with buttock lines.jrurBI5.png

The resulting work in 3D.IzSoJVh.png

Next I added in some rudimentary sketches for the bowspirit and jib boom.  This gave me a rough overall length of 273' to 274'.  

pKwwI3z.png

The next thing I wanted to focus on was the fact that I didn't have a midship cross section to work with, only small sections of individual parts like the keelsons and garboard.  A midship cross section is important, as it will help you lay out geometry and understand the interactions of the pieces more easily.  So I created this one to get a general idea of how she laid out. Here you can see her rather unique keelson setup.  Her sister keelsons were fayed to the floor and transitioned into her 4.5" floor ceilings.

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Next was adding planes for each frame station. I accidentally named the first plane m when it should have been l but I fixed that later on.

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The garboard is 7" thick at midships but thins out to 4" at the stem and stern. The frame angle varies from about 86º at the stem to 18.5º at midships, then back to 87º at the stern.  After doing some number crunching I came up with a rabbet line, shown here in blue. In this view we are looking down the centerline of the ship from just above the baseline so you can see how it warps.tUkiFY2.png

And then I added a bearding line for the keel, again highlighted in blue. Here we are on the horizontal baseline of the keel, looking at it from just right of centerline. If the above rabbet line is the warp, this curve would be the weft.

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SolidWorks finds it easier to loft a surface if you maintain some uniformity to it's geometry. I intend to do this in one surface if I can, so I am making each frame loft section full height. It might make more sense once I'm done.  Trust me, I'm a professional.:DDe2TWSg.png

Here I've finished adding in the port side lines.  As before, all lines go from the baseline up to the 36' line. These line remain unsmoothed as yet.  I will start smoothing them once all the lines are drawn.

bpimWUT.png

Looking from an isometric viewpoint, you can see where the bottom edge of the lines are constrained to the rabbet line (red arrows).  That will give us a good start for smoothing later. The blue arrow indicates a good example of how the lines are not smooth yet.  Even a well controlled spline won't always do exactly what you told it to and takes some coaxing.r8y1oYL.png

Aft of midships, I run into the rather small problem of having to draw lines on the starboard side of the ship.  The solution is rather easy, a simple mirror command, which necessitates we also add a centerline.

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Work on the lines nears completion.RHmsJ7i.png

Added in a rough estimate of the transom, this is probably not final. The green color is an approximation of the color of Zinc Chromate, the paint used on the insides of aircraft during WWII to curb corrosion.  The parts template I use for work has this color as standard, so just ignore it. Or don't, you're an adult, you can do what you want.W4ctAef.png

Added in planes to add in sketches for the buttock lines. I noticed that when I put the scan in for the reference image I forgot to scale it horizontally.  The blue plane lines should line up with the tick marks on the scan.  When you scan a drawing to put into CAD like this you need to scale it not only vertically but horizontally as well, and make sure the two are not linked.  Line drawings scanned from books are never scaled perfectly one to one in both axis.wBylp7Q.png

Here is the first buttock line. I added in a spline with the same number of control points as there were frames.  I then selected a control point and one of the frame lines and used the pierce constraint.  The control point of the spline is now connected to the frame line as if it "pierces" through the control point.  This let's us compare the model shape against the drawn buttocks lines.  The closer I can get the buttock lines to match the lines in the scan, the more accurate the hull will be.

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The second line is added and what I am seeing is that the frame lines and buttock lines from the scan are pretty good so far.

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Once all the buttock lines are in you can see that me not scaling the lines horizontally is probably causing some issues, since the gap gets worse the further out from centerline you get. I'm probably going to have to adjust the horizontal scale of that front view image again and redo all the frame lines.

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Just to check, I moved the planes I created outwards until they lined up with the wrongly scaled front view to see how the change would affect the buttock lines and the result says, "Yep, you're gonna have to fix em."

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I added the 39' 8" width in as a couple of reference lines mirrored across the centerline.  Then I edited the picture to scale it properly.  Remember to uncheck the item in the red box to ensure it doesn't just scale the whole image.

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Here's something I do a lot when I am tracing images for a loft.  I offset the spline by just larger than than the scanned line is.  In this case the line I scanned is scaling out to  around 3/4" thick so I offset at 1/2 inch in each direction (bi-directional) and check the offset geometry under construction to make the outside lines into construction or reference lines.

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Here's a close up of the result, you can see how it is helpful to get right down the centerline.

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Since I know the lines in the drawings I scanned are pretty good, I am going to start the smoothing process.  This starts by selecting the main spline and selecting "Show Curvature" in the properties manager.  You get a series of lines called  a Curvature Comb that you can use to check your spline.  You want a smooth comb without these kinks in it when you're done.

8gNbBaH.png

Next is to add dimensions to control points.  These are already constrained vertically so the only way they can move is horizontally.  Controlling them with numbers is the easiest way for me to smooth the curve. Here you can see we have a couple of bad spots but overall it's not terrible.

YkdnwHQ.png

Sometimes the result isn't a beautiful comb where it is exactly the same thickness throughout, in this case I'm working on frame Y which is in the transition area between the concave curve at the prow and the convex curve amidships. That little dent about 2/3rds of the way up is the remnants of the prow's concavity.

0VBddJZ.png

Usually you prefer to see something line frame g, which is straighter as it approaches the bow and begins to curve in a more uniform manner the higher you go.

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Smoothing is coming along, but is really tedious so to distract myself I have added some details to midship section. Lower planking was 4" x 14" up to the turn of the bilge. Turn of the bilge is a rather arbitrary term so I put the change where I thought it should be.  From there to her plank sheer the planking was 5.5" x 7". The width of the wales planks is only 7 inches, compared to the 14 inches of the the lower planks, this is because the curve becomes more pronounced and the 14" planks are too wide to accommodate the curve.  I might still pull out a couple of those lower planks and move the wales down and in a little more, I haven't decided yet, but the curve looks a little to much for those last two.  

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Her plank sheer is 5 inches think and her main rail is 5.5" x 20". Nothing else is dimensioned so the rest of this is best guess to get the known dimensions to agree with each other.  Her bulwark planking is 3" x 6" and only on the outside of the hull.  Inside her bulwarks are open up to the rack rail.  She has 4" thick clamps above and below the main rail, these fill the gap between the main rail and the monkey rail (fancy rail). I'm not sure about the waterway, in the description by Bruzelius they are said to be 14" square but this seems a bit excessive.  They would end up cutting away a quarter of the material when they cut the molding into it. It also doesn't leave a great deal of open space between the plank sheer and the rack rail, but that seems to be an aesthetic thing to me so I'm not sure if that's more than just my opinion.

D3aMQVo.png

The next question I need to clear up is the masts location and rake angle. Most of my work is based on the Chappelle drawings, so I kind of default to his being right most of the time, but here I have to disagree with him.  Bruzelius describes the rake angles of the masts in inches to the foot, while Chappelle drew them in angular degrees. In other words, Bruzlius says the fore mast is 1.25 inches rake to the foot. If you draw a triangle with one side 12 inches and the other 1.25 inches, you get a rake angle of 5.95º.  Chappelle has drawn his masts at 1.25º directly.  In my drawing each mast has two lines.  The solid line represents the rake angle in inches per foot and the dashed line in degrees. I think we can agree that Chappelle made the common mistake of replacing triangular dimensions with angular dimensions.

 

The second question is location and here I think Chappelle might be right but I'm not sure. Bruzelius describes the ship as being 202 feet between perpendiculars, but Chappelle describes it as 204'.  The reason for the discrepancy is the length between the frames.  The original waterlines, when scaled to 204' show a spacing between frames of 32". But at 202' the gap is 31.9".  a gap of 31.9 inches seems implausible, so 204' is the more likely length between perpendiculars.

 

Bruzelius' dimensions for the mast locations are 45' from front perpendicular to the fore, 67' from fore to main, and 53' from main to mizzen, with 37 remaining between mizzen and aft perpendicular. Chappelle, however has the given dims as 45', 68', 53'6", and 37'6". These numbers are in better keeping with the ratio numbers listed in Crother's Clipper book. The below drawing shows the masts located according to Bruzelius. The image below that has them located according to Chappelle.

 

These changes, overall, will make a little more room at the front of the main deck, but are going to make the poop deck a bit more cramped.

VyqwlpI.png

So, overall, this is where work has progressed to after about a weeks work.  If you guys see any errors, please let me know, I'd rather fix them now than find them later on.

JqbzicC.png

 

Edited by rtwpsom2

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A very interesting ship and great summary of your process; I will be interested in following this log.  I'll have a closer look later today but from my limited experience in drafting these sorts of plans (2D only), all looks pretty good.  there are a few guys on here with much more extensive knowledge and experience in this whom I am sure will be only too happy to help out in answering queries.

 

I am currently researching, and trying to draw (2D) a set of plans for the HMCSS Victoria (1855) which was fitted out as a yacht internally, but retained a Gun Despatch Vessel armament and equipment, many of which were very advanced fittings for that era -  purchased by, built for the colony of Victoria, but built in Limeyard Docks, London.  I am sure I will learn a few useful tips along the way; and if there is anything I can contribute will be more than happy to share :)

 

cheers

 

Pat 

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Posted (edited)

Just read up on the Victoria which taught me about the Burke and Wills expedition. It's interesting to see that Australia had it's own explorer expedition similar to our Lewis and Clark expedition in the US.  Pretty cool stuff.  The Victoria seems to be a fairly similar rig to the clipper ships, albeit powered of course.

Edited by rtwpsom2

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Both the drawing and your procedures are works of art.  Thanks for sharing.

 

I did not understand how the offset of the splines was used to center the traced working line.  This may be because I do not have access to Solidworks.  Still, I couldn't get my head around the theory of it, but it sounds like a useful thing to know in general (unless this is Solidworks specific).

 

It seems you have a very good original plan.  Even at that, I take it you did a bit of work to straighten some lines out prior to use in CAD.  I find all this very interesting.  The tools available to you for curvature analysis are fascinating.  In TurboCAD I rotate the drawing and eyeball down the line, a method similar to the actual method on the lofting floor.  I like the more accurate tools in Solidworks.  I believe similar tools are available in Fusion 360 and Onshape.

 

This looks to be a very interesting project.

 

Wayne

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Hi Wayne, as far as the offset lines go I guess it helps to think of how you draw the lines without offsetting them.   Your scanned line is this thick channel and you need to put your spline in the dead center of that channel.  But eyeballing it can often be difficult.  When you offset the spline you now have a constant width channel that more closely resembles the thickness of the scanned line.  Then you can use the gaps on either side to get a better sense for when you are truly in the center of the line. I don't know, it seemed rather intuitive to me, but I'm probably a little touched in the head, so it might not make sense to others.  Anyway, thanks for looking.

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Posted (edited)

Thanks - one day I hope to produce a 3D hull shape for Victoria but I am still getting to grips with her construction which used diagonal planking rather than the standard for/aft strakes on frames.  Above the 'round' she did not use traditional frames but rather iron plates (Lang's Plates) I am assuming.   These supported three layers of planking separated by sheets of impregnated felt with the two inner running at 30 degrees to each other, and the outer skin (planks) running fore/aft.  This method of construction was used as it provided greater hull stiffness/strength to cater for the steam power/propeller - more expensive at the outset but cheaper through the life span of the ship.  On her breakup some 30+ years later, the yard reported her hull was as sound as the day she was built.

 

She did have a similar sailing rig to clippers with many clipper ship rigging elements included that the RN did not incorporate until much later, and some not at all - all these improvements were in the interests of minium manning.

 

Anyways enough prattling on about Victoria; I will keep that for my log.  I will follow your techniques closely to see how you do this.  i have TurboCAD with 3D capability but I am not sure I will use that yet.

 

cheers

 

Pat

Edited by BANYAN

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Looking good so far! I look forward to future progress on this project. 

 

I am very interested in this, as I would love to be able to take lines drawings for ships and turn them into full 3D models. Seeing things in 3D really helps me when it comes time to build things. 

 

Keep up the good work!

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Interesting log, so far. Is it possible to find primary sources for information? What source did Chapelle use to draft his version? Again, Bruzelius is a secondary source, unless he is quoting a primary one. I'm not sure either of those sets of mast rakes is correct! One seems too little, the other too extreme.

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With regards to mast rake angles, in some latter clippers, and with Victoria, the rake angles were indeed 'extreme'.  I have a discussion in my log, but from the only surviving drawing by the ship's designer (Oliver Lang) the rake of Victoria's masts were from fore to aft - 5 deg, 10 deg and 15 deg.  This caused some disbelief at first so I overlaid the rakes measured from a profile photo, two lithographs and the plan and it was indeed as extreme as the plans suggested.  

 

The differences in positions can be accounted for by the various 'aspects' the ship was depicted - the photo is slightly stbd bows on, one of the lithos slightly port bows, the plan true profile etc.

 

5b4fdac6ef400_MastRakeHMCSSVictoria.thumb.png.9c5a74dd8c0d0f5efec6f3b6cea87bad.png

 

cheers

 

Pat

 

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Posted (edited)

Druxey, The Bruzelius article I mentioned is transcribing a Boston Daily Atlas article from May of 1851. The numbers Bruzelius publishes match the numbers Crothers published in his masting book.  For references Crothers cites the same article but he viewed it directly from the microfilm from the Library of Congress.  I cannot speak to the authenticity of the original article, in fact I do question a couple of minor things as denoted before.  However the numbers given are most likely accurate to the 1851 article.

Edited by rtwpsom2

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Posted (edited)

The Boston Daily Atlas is, in general, a very good resource for reasonably accurate descriptions of vessels, taking into account that at least some of the narratives were as much braggadocio (by owner and builder) as factual.  The owner may embellish in order to one-up competing owners (and, perhaps, for ego enhancement).  The builder may embellish to gain more sales.

 

Either way, newspaper accounts are pretty good references.

 

Chapelle, regrettably, was very lax in his citation of sources used. 

 

Howe and Matthews (1986 Dover reprint) provide 4 pages on the ship, though no citations.  Some highlights:

 

220x40x21 and 1498 tons (om) or 997 tons (foreign measurement).

 

The mast rake varied - fore 1 1/4, main 1 1/2 and mizzen 1 3/4 inches to the foot.  Also provides mast lengths and so forth.  Probably, based on the syntax, from the news article.

 

David MacGregor in The Tea Clippers offers an alternate lines plan and a photo of the model by McNarry.  He also uses the 220 foot length (note that Lubbock went with 202 feet) in the text, although the plan uses 202 feet.  While the notes on the plan are difficult to read, I could make out that it was based to some degree on that of Chapelle.

 

 

 

 

 

 

 

 

Edited by trippwj

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Thanks, everyone, for the comments to my question. If only the chainplates were indicated on the Chapelle drawing, it might offer further clue as to the mast rakes....

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Posted (edited)

Yeah, not having those are going to be a problem in more ways than one. 

 

Wayne, I'm still waiting on my copy of Tea Clippers, I ordered it a month ago and it still hasn't shown up. Damn amazon vendors.  I think all the sources agree on a LOA of 220'.  I'll check again with the lines from Tea Clippers once it comes in, but I just can't get the lines from Chappelle to resolve the frames at 202' between perpendiculars. 

Edited by rtwpsom2

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Damn, you just brought up some memories. I was looking over the list and saw John Lambert's name in there.  I considered him at least a pen-pal if not a friend.  I first got in touch with him in 2010 about some weapons drawing he was doing and we started regularly emailing each other. I was rather melancholic when I found out he passed a couple years ago. He was a good man. 

 

I didn't see the Witch listed in their collection, but I will ask someone over there just to be sure.  If I decide to stick with the Chappelle drawings, I probably won't need the Smithsonian set, unless they provide more detail into her cabins or fitment.  

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Posted (edited)
On 7/18/2018 at 6:02 PM, druxey said:

Interesting log, so far. Is it possible to find primary sources for information? What source did Chapelle use to draft his version? Again, Bruzelius is a secondary source, unless he is quoting a primary one. I'm not sure either of those sets of mast rakes is correct! One seems too little, the other too extreme.

Looking at Crothers, most of those with mast rake given in table 29.1 refer back to reports (contemporary) in the Boston Daily Atlas.  Duncan MacLean, over a 7 year period, provided information on some 161 vessels.

 

Mast rakes given in the table by Crothers (main mast, inches of rake in 12 inches) range from "nearly vertical" to 1 1/2" (or about a 7.1 degree rake for the Witch).  Note thst there are several with that degree of rake.

 

 

Edited by trippwj

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