How to develop frames without buttock lines?

[tkay11]

I have seen a few builds of La Jacinthe (including Frolich's) with full framing. However, I don't see how to develop the frames without sufficient buttock lines. I have a feeling I am missing something dead easy, but can't remember it or think of it.

 

The attached drawing is part of the sheer plan drawn up by Boudriot. It shows a few buttock lines, which don't extend much further than bulkhead 10. There are of course buttock lines shown on the half-breadth plan, but these don't cover the full width of the hull.

 

 

I'd be grateful for any hints or suggestions to put me back on the right path!

 

Tony

[PietFriet]

Tony,

My thoughts on this are that you need two 2D drawings (or offset tables) to get the 3rd dimension. In that case it would also work if you had the water lines instead of buttock lines. Otherwise, I don't know how you would get the frames so hopefully I learn something new as well!

[druxey]

Another assist in arriving at a fair hull are using diagonals. (These are the angled 'waterlines', if you like.)

[tkay11]

Thanks, @PietFriet and @druxey. I think I might have got by, had there been a body plan as well as diagonals. Unfortunately there are neither. The plans only show the half outlines of the fore & aft sections of the bulkheads. Could I prepare diagonals from these?

 

One thought I had was to make outlines of hypothetical frames from a combination of two adjacent bulkheads, but that would result in fancy that I am not sure would work.

 

 

Tony

[PietFriet]

One thing you could do is to enter all information you have in Delftship and then shape the hull respecting the given data (you can lock data points). Once done, you can create frames at every location and I would imagine it is sufficiently accurate for a model. I found Delftship quite intuitive and worth the effort to get to know how to use it (I used a ship contract to determine the hull shape only with no requirement for fancy looking ship in 3D software). The free version is sufficient to do this.

Piet

Edited July 12, 2021 by PietFriet

[tkay11]

Interesting thought, @PietFriet. Thanks. I'll have a look and more of a think. Now that I've tried matching the bulkhead drawings to the sheer and half-breadth plans with waterlines, there's a lot of discrepancies to work out as well. I can see 3D modelling may be the way to go.

 

Tony

[Dziadeczek]

Ages ago I had to hand draw missing frames from Boudriot's plans for my 74. He only drew the so called station frames, but "for the clarity of the drawings" omitted the others. It took me considerable time to do it (of course, like mustard after dinner, later on Ancre issued addendum to the 4 volumes with ALL frames included, lucky me...  😬 ).

I remember I used waterlines from a half breadth plan as well as a body plan to draw missing profiles. It worked...

Edited July 12, 2021 by Dziadeczek

[tkay11]

Thanks, @Dziadeczek, I've started just with the station lines, and, as you and @PietFriet suggest, this may work out ok. I think I've been too fixated on buttock lines.

 

Tony

 

 

[druxey]

Yes, Tony, there is just enough information on the drawing you show to reconstruct body plan (waterlines, if you need them) and proof diagonals to see if everything is fair. If you know frame spacing, you could even derive all the frame drawings. The buttock line help define the rapidly changing form of the hull at the extreme aft end

[tkay11]

Thanks @druxey. Yes, I've been doing it on the basis of waterlines, but have had a problem determining the upper margins where the deck meets the edge. I'm overlaying all the half-bulwark drawings so I can get an idea of the line of the deck, and hope that will help. I can see the buttock lines helping at the rear. This is something I've been meaning to do every since reading Underhill's books some years ago. It's quite satisfying by very time-consuming. Still many frames to go!

Tony

[druxey]

Yes, lofting frames is a bit of an endurance test, but very satisfying once you start assembling a framed hull!

[Dziadeczek]

On the drawing you provided, Boudriot indicates spacings among the frames - the middle spots shown as short vertical lines between frames 1-10. From these points I would draw vertical lines up to the deck (in red on my copy) and from those, I would draw two (green) lines parallel to the red ones  showing the "thickness" of your missing frames, and thus placing the "rest" of the frames on the plan. La Jacinte was not a big, heavy, Navy ship having many tightly spaced frames, like the ships-of-the-war, so I would assume that in between station frames (1-10) there was another, one ordinary frame (unless someone has a better info).

Do the same on your half breadth plan (vertical view of the hull). 

On the intersections of these lines with your waterlines (on your half breadth plan), you will have points, delineating shapes of your missing frames.

Edited July 12, 2021 by Dziadeczek

[tkay11]

Thanks, Dziadeczek. This is exactly what I have been doing. However, if you compare the heights of the frames shown in the cross-sections, they do not seem to match the heights on the sheer plan. It seems he took the heights of the cross-sections from the bottom

of the keel but the heights then don't all match the heights of the deck on the sheer plan. This left me in a quandary as I feel the only solution is to re-draw all the bulkheads as shown using the sheer plan as the reference for the heights. I was intending to add only the bulkheads between the shown bulkheads, so that would fit in with your suggestions.

 

Thanks again

 

Tony

[Dziadeczek]

Hi Tony,

The way I did it, I took a sheet of a grid paper (with 1 mm increments) big enough for the entire frame, and drew two lines on it; one horizontal line near the bottom of the sheet and 2nd line vertical through the middle.

Then I drew several horizontal lines, parallel to that first horizontal line, but at various heights, the distances between being exact with the waterlines on your sheer plan. These lines will represent the same waterlines on your body plan (sections' plan).

Then take a compass and from your half breadth plan take distances between the keel and each waterline for each frame and transpose them onto your body plan at the corresponding waterline, and repeat this for all waterlines. Finally connect all points into a curve representing the half profile of your frame. In order to obtain a full profile, bend the sheet at the vertical line, place it on a light box and with a pencil trace the opposite profile.

Or, when you mark the above mentioned points on your body plan, mark them symmetrically on both sides of this vertical center line.

This is done manually, folks with computer programs can do it much faster, but I did not own such a program at that time.

This curved line only represent a mid section in between both parts of this "sandwich" that makes a frame. You will have to draw a few more lines like that in order to have a full shape of a frame. See, each frame hypothetically cut horizontally at a given level has a rectangular shape - for the mid frames , but this shape changes as you go towards the bow and the stern of the hull - they become progressively parallelograms due to the hull's oblique shape. 

You have to determine these shapes - for each frame and each waterline level. At the end you will have four curves - for each waterline, one is for a forward outer  profile of a given frame, second is for a forward inner profile, third is for a rear outer and fourth is for a rear inner profile, so the entire process is quite laborious and time consuming, done manually.

English is my second language, thus perhaps my explanations are not adequate enough, but I found a pretty good article on the internet, by Gene Bodnar, explaining everything in detail. Here is the link:  SCRATCH BUILDING A MODEL SHIP (modelshipworldforum.com)

 

Jean Boudriot is generally very good and precise in his plans and drawings, but as always, there is no guarantee and mistakes happen.

 

I suggest you make your own body plan (transverse sections) for all frames, making sure about their proper heights at the level of the deck and/or rail.

 

Regards,

Thomas

 

Edited July 12, 2021 by Dziadeczek

[Jaager]

Some ANCRE plans are a bit inconsistent as to which line is used as the baseline from sheet to sheet. All of the lines are where they should be.   You must choose which of the lines will be your baseline.  You use that same line for every sheet and ignore the view selected baseline if it is different from your choice.  Unless the hull has drag, my favorite is the top of the rabbet.  Some plans have the frames go down to the bottom of the rabbet.  I would rather cut the rabbet into the top of the keel.  If the rabbet is part of the frame, it gets fairly thin and is sort of like the frame is balancing on a point.  Also, rather than cut a notch in the keel for the floor timber, add the chock on top of the keel.

 

For me, the worst part of plotting each frame is drawing the curve. Three points define a curve.  You can get a curve for a frame by connecting three or more plotted points.  But that curve is unique. It may or may not be related to its brother curves on the frames before and after it   Getting a fair hull is challenge enough when the curves are related.

[tkay11]

Thanks again, Thomas and Jaager, for your advice and support.

 

For Thomas' point, the reason I was hung up on buttock lines was that this was the way Underhill showed how to do it (using compass and paper) in his book 'Plank-on-Frame Models'. So I had completely overlooked and did not think of, the fact that I could use waterlines with equal effect, until PietFriet's comment at the top of this post stimulated me to think about it. More to my shame, your mention of Gene Bodnar's article reminded me that I had in fact downloaded this in 2014 but had totally forgotten it. So it looks as though I'm breaking one of the primary principles of MSW which is to do my research first! All the same, thanks very much for jogging my memory in this way.

 

For Jaager's point about inconsistency in the Ancre plans, I admit having been very puzzled about the approach to the plans as at first I could not make the measurements on the cross-sections tally with those on the sheer plan. It took me a while to realise that whereas the plans show a layer of planking above the cross-sections, Boudriot had in fact drawn the cross sections to the top of the planking and must by oversight added an extra layer of planking on top. In fact this mistake of his could work in the modeller's favour as they could then choose the thickness of deck planking to suit and just deduct it from the heights of the frames shown in the cross-sections. Of course, this problem would be entirely overcome should I continue to develop the frames in the way you suggest by just using the sheer and half-breadth plans as reference.

 

You are right, Jaager, about the lines for the rabbet and keel all being correct. And I take your advice about cutting the rabbet into the top of the keel. I have not had much success with rabbet-cutting before, so I'll be practicing it first.

 

Thanks to everyone who has commented so far, and I hope it hasn't been too much of an irritation to those who feel I should have put a bit more thought into it before posting. I suppose I'm getting old!

 

Should I continue with this as a build, it may well be interesting to go into the details of the plans to help others who come across similar difficulties. This discussion has been very helpful in clarifying what needs to be done.

 

Tony

[AnobiumPunctatum]

You can use horizontal lines or a combination with horizontal and buttock lines.

If these lines are not in the plan set, you can create these with the body plan.

[tkay11]

Thanks, Christian. There is no body plan, so I am making one using the cross-sections super-imposed and then joining the top edges. I take the point about making the buttock lines, but these are not shown on the half-breadth plan (other than for the last two frames).

 

Tony

[Jaager]

7 hours ago, tkay11 said:

Thanks, Christian. There is no body plan

Tony,

Actually, there is a Body Plan of sorts.  Plan 1  part C   is the Body plan with each station cross section in a separate box.

And if you look - Station 1 and station 11 are also there.  A bonus is that Boudriot has done all the planning and plotting for you for the bow and stern. Cut the pieces using his patterns and assemble.  Would that NMM plans had this feature!

 

Each has a bevel - for the frame on the side away from the mid-line.  This means that if you wish to do the frame lofting  using tradition methods, the outside shape of 9 frames has already been done.

I think the horizontal line at the bottom is the bottom of the rabbet.

This is easier done using a raster based graphics program.

Scan, adjust for scanner scale artifact.  Select the background and CUT. There is now a transparent layer with just the lines on it.

Make a Base grid.  baseline / vertical midline /  vertical buttock line locations / horizontal WL locations.  With this behind each station cross section you can get the desired points.

If you duplicate the base and duplicate a station cross section  pair the two  then collapse to a merged layer  - you can use the rectangle  select tool to get each data point as its own layer - move it where needed - rotate it if it is needed for a 90 degree different perspective.  This removes the human measuring error when setting points to plot.

 

One factor about raster based graphics - these programs do not do smooth curves. Depending on how many points are used to draw a curve, at some magnification it will look faceted - saw tooth -   This is not what is best for laser cutter plot, but if you go from plan to pattern to cutting wood, there is no way that you could replicate a micro facet effect on actual wood when sanding or planning to shape.

 

GIMP is free,  Photo shop is monthly rental,  PaintShop Pro is not expensive,  Painter is expensive.

Edited July 13, 2021 by Jaager

[tkay11]

Thanks, Jaager. That;s what I have been doing. I am taking the measurements straight off scans which are embedded in TurboCad. I put them into a spreadsheet, and then use the measurements to draw each of the bulkheads (rear, centre and fore for each one). This process is far quicker than I thought it would be, now that I have some kind of work process established.

 

I now don't use the bulwark outlines, just the sheer and half-breadth plans. I'll follow the process suggested in the monograph for frames 1 and 11. The bulwark side outlines in the original plans are accurate, but their deck outlines are too high. So I'm adjusting the top surfaces accordingly. I've also added bulwarks between each of the existing ones to form a stronger build. I'll be doing plank-on-bulkhead rather than making frames as I plan to work in 1:79 rather than the 1:48 of the plans.

 

Why 1:79? Just because the basic longitudinal bulkhead fits on a sheet of A4!

 

Again, I'm just experimenting with techniques, so this may never get to be a build log.

 

Tony

[Jaager]

Tony,

 

You can do larger if you use legal paper  8.5 x 14.

The price difference is out of proportion, but I get more timber patterns on a page and thus fewer pages to lacquer coat.

[tkay11]

My scanner/printer only takes 8.5x11ins or A4 max! So I'm happy to work at that scale, especially as I want to work at smaller scales which still allow some definition of the rope to be seen. My smallest rope at this size will be 0.2mm diameter, for which I use Skala 360 at 1 thread per strand and 3 strands in all.

 

Tony

[AnobiumPunctatum]

You only need to scan the body plan. Measure the length between the first and last station line in the sheer plan. Then measure the distance between the station lines to check and correct the first measurment. With this information you can draw the station lines in your cad-system. The offset between the station lines is the same.

 

If you have scanned the body plan you can add it to your sheer plan and then the funny part can start. These are the steps I started my Triton drawing

[tkay11]

Thanks, Christian, for reminding me about your Triton build. A really great undertaking. I really appreciate your plans reconstruction. How is it getting along? Have you yet decided to get back to a build?

 

Tony

[Jaager]

Christian,

 

Station intervals  are not always constant.   My current subject is an NMM plan.  The majority of the stations are at 3 bend intervals, but the last one at either end are 2 bend intervals and the dead-flat has a skip to get in step for floor placement by having 2 bends and a single frame.

HIC copied a lot of original plans as drawn and Falmouth has three 8 bend intervals in the middle, then it goes to 4 bend ans a 3 bend at each end.  Stag Hound is majority 4 bend but goes to 2 bend at the ends.  ANCRE plans tend to be constant interval and it can make dealing with the ends interesting when the bevel becomes significant and the reference points are a bit sparse considering the difference.

[bricklayer]

Tony

The Station lines themselves aren`t drawn on the bulkhead-templates. If they were drawn, then they`d run in between the inner and outer contour lines (fore and aft lines) of the bulkheads. That`s because the station lines are located at 1/2 the thickness of the bulkheads. The same applies to hight of bulkheads. There`re dotted lines that run parallel to the deck camber. The dotted  line indicates the rear, invisible edge of the bulkhead`s deck camber.

 

Two orthogonal views should be suficcient to define the shape of a hull. Station lines + water lines or station lines + buttock lines or water lines + buttock lines. Taking into account a third view may lead to confusion and uncertainty because the views of hand-drafted plans don`t match properly.

 

If the lines of different views don`t intersect, then there`s nothing but guessing and re-fairing the lines. Which one is most true?  Station lines, water lines or buttock lines? Once you know how to operate a 3d modeler like Fusion 360, Rhino 3d or Delftship then it will provide most reliable hull shape and lines. Their analysis tools show how smooth and fair lines and surfaces are. Curvature graph for curves and gaussian curvature, shading and zebra striping for surfaces.

 

I modeled the "sea bright skiff" published by John Gardner in Delftship. I strictly followed his table of offsets. The lines, which each represent the upper edge of a strake, look horrible in both top view and longitudinal view. These lines are neither water lines nor buttock lines nor diagonal lines. They show the run of the strakes.

 

The lines and the shape of the hull may satisfy you. After having applied those tools mentioned above they won`t do anymore.

It ain`t easy to determine that the fairing or lofting job is completed. Major alignment is done quickly. Minor alignments may take an eternity.

 

You`ll find an appropriate way as you did in your previous builds. I like both boats that you already completed by means of Ancre plans.

It seems that the Allege was a real challenge.

 

 

Michael  

[Jaager]

3 hours ago, bricklayer said:

The Station lines themselves aren`t drawn on the bulkhead-templates. If they were drawn, then they`d run in between the inner and outer contour lines (fore and aft lines) of the bulkheads. That`s because the station lines are located at 1/2 the thickness of the bulkheads. The same applies to hight of bulkheads. There`re dotted lines that run parallel to the deck camber. The dotted  line indicates the rear, invisible edge of the bulkhead`s deck camber

 

Michael,

I do not see this at all the way that you do.  There may have been a few exceptions - perhaps fish holds and such, but in general western wooden vessels did not have bulkheads.  Large Chinese sailing vessels had bulkheads.   While not all vessels were framed using bends - a bend is a pair of frames and a strong structure - the timbers of one overlapped the butt join of two of its partner.s timbers. -   a station IS the mid-line of a bend.  As such, it provides the shape not one, but two frames.   If it was all single frames, the station would be one face or the other of a frame.  (#)  The station  was the primary part of a plan, enlarged on a mold loft floor and used to shape the timber patterns.  Richard Endsor describes these station patterns having sirmarks that allowed these same patterns to be used the shape  the frames between and up to the next station.

POB uses molds.  The entire method is an artiface.  The molds can go anywhere,  The method is easier to do if an already existing station pattern is fixed to mold stock  and shaped to make a mold.  For some reason, early Italian kit mfg termed their molds as "bulkheads".  Perhaps the writer of the instructions  was ex navy. In any case no end of misunderstanding has followed.  The station pattern is placed on the mid-line side of the mold. 

As for the deck, the solid line with the deck plank hash lines above it is the top of the beam. Or where the top would be if there was a beam at a station.  Beams followed their own location rules - ignoring station locations.  I am guessing that Boudriot added the beam shape to his station plans so that should a molder build the vessel using POB, the mold made using each could have a pseudo-deck beam as part of the mold and avoid modeling actual beams.  The profile plans provides beam location, the height at the crown of the deck and intermittent marks showing the underside of the deck at the side.  What the solid or dotted lines below the beam camber are intended to show is not obvious to me.  The bevel of a deck goes up, not down.  The thickness of a mold is arbitrary and entirely up to the builder.

 

(#) With traditional POF where a bend is glued up and a pattern applied for shaping, A station is of no use and they tend to ignored.

[tkay11]

Thanks, @Jaager and Michael (@bricklayer). Good comments. I have already created the station lines which I will use as  reference points for the moulds or bulkheads, and will determine the sided width of the moulds before determining their outlines.

 

I hadn't known about the origin of the use of the misleading term 'bulkheads', so am thankful for that bit of explanation. All the same, as it is now common usage, I will continue to use it, a bit more cautiously perhaps.

 

Thanks also for drawing my attention to 'sirmarks' or 'surmarks' -- the latter making the etymology clearer as marks made on the moulds of a ship to show  where the angles of the timbers are to be placed. It made me read up about their use. This is very nicely described in an article on the web site Boats & Builders, where they look at whole moulding and quote Erin Mckee from his book Working Boats of Britain: Their Shape and Purpose (1983).

 

I understood that Boudriot was using the top of the moulds to act as beams, but the problem is that he drew these to the top, not the underneath, of the planking. So the layer of planking he placed on top of them is far too high as well. I've had to correct that in re-drawing. You can easily check this for yourself with a pair of dividers by comparing them to the sheer view. As Michael suggests, the dotted lines below the beam camber are the camber of the deck in the adjacent paired mold or bulkhead. The deck goes down from the stern, then upwards again from about bulkhead 3.

 

I love such discussions that deepen my knowledge!

 

Tony

[bricklayer]

Jaager

 

I referred to the image in post #4. I called the patterns No. 5 to  No. 10 bulkheads. The words moulds or formers may be more suitable than the word bulkheads. I know the original meaning of the word bulkheads that devide a hull into several watertight compartments. But the word bulkhead is widely used to replace the word mould. Strictly spoken one word isn`t interchangeable with the other.

Dziadeczek traced some lines in red and green. I think that two adjacent green lines define the thickness of the pairs of frames (bends) or the thickness of the moulds. The red  line in the middle is the actual station line.

The moulds No. 5 to No. 10 don`t show the corresponding station lines. They only show the adjacent green lines, the fore and aft of the bends or moulds.

 

I have to admit that I didn`t read Tony`s initial post thoroughly. I thought that he intended to add further moulds, only. E.g. mould 5 1/2, 6 1/2 and so forth. Now I understand that he wants to transform the POB drawings into POF ones. Are there drawings of La Jacinthe other than the ones that Boudriot drew? A set of drawings that shows all timbers, the whole interior? If not then I wonder how to determine the dimensions and the location of the joints of scantlings.

 

That`s a true challenge.

 

Michael  

[tkay11]

1 hour ago, bricklayer said:

I thought that he intended to add further moulds, only. E.g. mould 5 1/2, 6 1/2 and so forth. ... If not then I wonder how to determine the dimensions and the location of the joints of scantlings.

 

Frolich in his book 'The Art of Ship Modelling' describes in detail how he converted the Boudriot drawings for a fully framed model. He used the station lines, as well as the half-station lines, as reference points and placed double frames on either side of these. Boudriot does have a fairly full list of the scantlings which include moulded and sided dimensions of the frames. I am not sure if copyright prevents me from showing pages from Frolich's book, but it is very interesting. Of course, he had to design the stern timbers and fashion pieces as well as the bow cant frames himself using the Boudriot drawings as a base, and with reference to ships of the period and type.

 

My initial puzzle was how he could have designed the frame outlines without buttock lines as that is method suggested by Underhill and Bodnar as well as others in referring to creation of drawings, but this thread very quickly made me realise that I had completely overlooked the utility of waterlines.

 

Frolich used a solid mould on which to place the frames, with a space in the mould for the keelson, just as one would for a small ship's boat. It really is a beautiful model. He says it was just to fill time between builds, which rather took my breath away when I first read it several years ago.

 

My initial aim was to see if I could draw the frames as well, but then realised that at the scale I wanted, and given my mediocre skills, it would be safer to do plank on bulkhead. However, I am drawing moulds for stations 2.5, 3.5 etc, and that is quite easy to do as well. For me it's more an exercise in draughting and using another way of approaching a build from plans. So Michael is correct about my initial purpose, it's just that I altered direction as a result of the wonderful input from you all.

 

Tony