Frégate d'18 par Sané , la Cornélie

[JohnE]

LOL. That sounds like something that Cartman would have said to Nero (sorry, a bit of South Park humour there)

 

Found several places where I screwed up. Getting meticulous over all the data. My program is outputting some very pretty major arcs. The reconciling curves are fitting into place on the diagonals. Boy, oh, boy, am I learning a ton about French period naval architecture. Am happy with the bow sections in the body plan so far.

 

Breathing a large sigh of relief, I'm off to do the stern sections using the same paradigm. If this works like I hope, then one more day will see a half-breadth of the diagonals, and one more will see a half-breadth of horizontal waterlines. Hootz, gazootz !!

 

Anticipating the question from Gaetan, Gerard, and others, I am paying particular attention to "dehors des membres" and "dehors des bordages" data entry notes.

 

John

[JohnE]

Ok, stopped widdlin’ and got to fiddlin’. Appended is the bow section body plan with construction marks and diagonals. If these ain’t the official plans they, sure as shoot, oughta be.

Am in the midst of the stern sections and the paradigm is working perfectly. As a further check, I’m running a rolling half-breadth plan just to make sure that the body lines plot fair. I’m anticipating another day or two to complete the entire body plan. I should have a fair diagonal half-breadth plan when finished. Will post.

 

Given this, a waterline half-breadth is a no brainer. I’m plotting at 1:12 with 4 sig figs behind the decimal. Boy, oh boy, does this project have a ton of Excel files !!

 

Thank you Henri-Louis Duhamel du Monceau, Honoré-Sébastien Vial Du Clairbois, and Gérard Delacroix and Hervé Sasso who brought us all together and who provided exceptional assistance just when I needed it most.

 

John

Edited September 12, 2015 by JohnE

[uss frolick]

Eric Cartman is my hero: "Respect Mah Authori-tah!"

[JohnE]

The paradigm worked so well, I just had to show it. Ta Da, the Body Plan of my Cornélie.

 

I was really afraid when it was time to put in the final marks, after doing the section curves. I dropped in the "lisse d'Hourdy" stuff from the devis and my hands were shaking, I almost couldn't click enter. Damn ! if it wasn't almost perfect !!!!! two tenth's of an inch after flowing in from the master couple, eighteen feet away. I am feeling very comfortable about my body plan.

 

Actually, it's the body plan from the "Devis d'exécution des frégates La Justice et La Cornélie", dated March 1810 and signed by Jacques-Noël Sané, along with some visual assistance from a possible plan of this version of La Justice maintained by SHD Rochefort. Detailed references available on request.

The Sané Frégate d'18 of the règlement, took its lines from the Virginie Class frigates Justice and Cornélie, built at Brest and launched in 1794 and 1797, respectively. So the lines of the paradigmatic "Justice" should work equally well for Cornélie.

 

In an ahistorical note, the original ships had that abortion of a poop. I hate it. Jean Boudriot didn't like it either, but was kinder and just called it unaesthetic. The devis and the Rochefort draught profile plan are without this 'feature', and necessarily require some adjustment in the Rabattue and lines of l'Estain. So my Cornélie will have more flowing lines in the aft profile.

 

John

Edited September 16, 2015 by JohnE

[JohnE]

Boy, howdy, am I learning about French ship design.

 

A word of caution about the aft end of French ships. Station VIII is a vertical station, but station IX is not. Station IX is l’Estain, which is the trace of the lower portion of the fashion pieces of the stern. L’Estain is a compound piece: it is canted inward (lateral), but also canted forward (vertical). It is routinely shown in French plans, but as a guide, not necessarily as a line model.

L’Estain is on traditional French Body plans; yes, but only as an aid – a projection of the exterior shape of a multi curved object expressed in rectilinear space. People more familiar with the British system of measurement can easily get confused with the French paradigm, particularly where ‘other’ measurement stations are adapted to National technical practice.  People who use l’Estain as a vertical section will end up with impossible buttock curves.

Realizing the lines are way more relaxed, both horizontally and vertically, can only help. There is a reason Monsieur Boudriot put his special buttock lines (a, b, c, d) in both his 74 Gun Ship and his Venus.

 

John

[druxey]

So, if I understand you correctly, the line of l'estain in the body plan is the projected view of this element?

[mtaylor]

I've seen that and puzzled over it. Now that you explain it, John, it falls into place. 

[malachy]

This is how it looks on the sheer, by the way:

 

 

It´s for a danish ship but they used french methods at the time. What´s really puzzling is that the red lines are perfectly straight on the waterlines plan.

 

(and sorry for derailing your thread, John)

[druxey]

Bava: it's not puzzling when you realize that the lines (that appear straight on the half-breadth plan) are their projected shapes on the sheer plan. They would only be straight if the ship were a rectangular block. Cut a loaf of bread straight down, but at an angle to its long axis, and view it from the side. Then you'll get it.

[JohnE]

Bava, you did not derail, You make an excellent point that is right in line with the discussion. Please keep on contributing.

 

Yes indeed, Druxey, it’s a projection. Bava’s post shows some of the ‘whys and wherefores’. Vial has a very nice section in his treatise about “Des Estains”, where he notes this and gives a caution

.

"Les estains sont les pieces de membrures auxquelles aboutissant les barres dont nous venons de parler (ed - Des Barres d’Ecusson) ; on voit l'un d'eux projete sur un plan horizontal en E e … . Aucune de ces projections n'en donne le contour au vrai, parce qu'ils ne sont, dans aucun de ces dessins, dans le plan du tableau."

(Rough: The estains are the frames that abut the transom pieces. We see one projected on the horizontal (elevation and vertical) plan at E. None of these projections give a true outline because they aren’t in the plane of the design drawing.)

 

All the other body plan lines are taken from vertical stations. When it comes to frigates, the French did not use cant framing and all of their "couples" were "square", from tip ta tail. However, although shown as a design curve on the body plan, l’estain is far from square and very far from vertical. This makes modeling the lines in the buttock region very exciting, when depending solely on the traditional plans.

 

Here’s a scan from one of Vial’s Plates showing stern construction for a 74. You can see the two planes of cant, as well as the compound curvature at the base. Clearly, if the curved section were angled forward a bit more, the buttock planking run would be a bit more relaxed. Conversely, if it were viewed as more vertical, the buttock planking run would have an exceptionally hard edge to overcome.

Woof !!!

 

for some reason, the image won't load. I'll try again later.

 

John

[JohnE]

OK, got it working (sort of). You can see, from Bava's post, just how far off vertical the lines are in one direction, but you still can't see how canted they are fore and aft; that's the drawing in the bottom right and the subject of an entire figure in Vial's treatise that has circles and arrows and other evidence that will be used against us.

 

Oh, by the way, all them little marks and lines and such are used in the design process. Vial has many figures of geometric tablature and extensive explanatory text sections. A very nice feature is that items in Vial have names that correspond, one-to-one, with items in the Devis’. The French did a lot with mathematics and it’s very apparent in Vial. Actually, it’s perfect for one using CAD to reproduce lines.

 

Happy days. John

[druxey]

Thank you, John. So, if I understand correctly, the lower part of l'estain is like a cant frame, and the upper part twists to become parallel to the couples.

[JohnE]

Druxy, it's kinda, sorta, the reverse. The upper part kinda, sorta, conventionally cants; it's a straight line, but the bottom is angled forward, and the whole magilla is canted - the top more than the bottom. The lower part has compound curvature in two major planes and has an angular offset, besides. Woof !!  The next few days/weeks will hopefully make this clearer.

 

Progress. Have waterlines for the little darling. They are horizontal, parallel to the keel, and spaced-apart by 2 French feet. They actually look pretty good. Diagonals are coming soon.

 

I'm departing from French practice by defining a series of 5 buttock-bow lines, spaced-apart by 3 French feet, starting at the vertical centerline. I am reminded that the point of the exercise is to develop a plan set that can be used by modelers to actually construct one of these. Anyway, Mistress Cornelia, in her latest suit of clothes.

And just for reference, here's the body plan with the marks.

 

If there's one thing I have learned in this project it's discipline, encore la discipline, et toujours discipline.  Ok, the lines get done back to the lisse d'hourdy and l'estain. Major project to loft the stern and get things righteous. Things will be good up to that point, and will get adaptively tweaked as life rolls on.

 

Ciao. John

[JohnE]

More progress.

 

Here's the half-breadth; waterlines below, diagonals above. Diagonals look really fair. No hard spots at all. Easy planking.

Going to have to loft the stern assembly in order to finish the lines, but they are good to go as far as they extend. I could just copy the buttocks and fake it, but I would rather put in the work to make them as consistent and faithful to the original devis as all the other lines.

 

That's another reason for adding buttock-bow lines to the draught. You end up with a rational 3-view space, having definite orthogonal, cartesian, entry points. The buttocks can be modeled in a relatively straight forward parallelogram. Interior boundary points are from the specs of the wing transom, and all the filling transoms. Lines for planking runs can be superposed over endpoints. Where there is discontinuity, or impossible hardpoints, perhaps the stern timbers could be adjusted a bit (Oh ! The Horror !) to make things a skoosh smoother?

 

Well, I did say I would be doing this like a yard dog would go about it. Can't imagine them mindlessly hewing to the instructions if it meant the sacrément bordé wouldn't take the curve.

 

Happy Days. John

 

 

[JohnE]

Wing transom is 13 pi thick, top-to-bottom, and 11.5 pi fore-and-aft. This is from Morineau and a bit old; but Vial tends to agree 30 years later (13 x 12 pi). It rounds aft by 1/3 of its length, reduced to inches, making the round-aft about 7.5 pouces (7.33 pouces according to another methodology). It rounds up as for beams, in proportion to its length. This would have the wing transom round up about 5 po (4 po, 7 li according to another methodology). I went with 7 po, 6 li, for round-aft, and 5 po round-up.

 

Know exactly where the wing transom went (according to the devis), so plop it in. Sane has 4 filling transoms (early ships may have had 3, c.f., Virginie), Forfait used 5 thinner ones (c.f., Amazone), where he didn’t use vertical transom timbers (c.f., Junon). Sane’s cant angle was typically 20 degrees. From Morineau and Vial, we have the different displacement angles of the filling transoms and their lengths (their spans actually, ouverture in French terms), so we can do the line of curvature on the profile plan, and use a 20 degree cant line.

 

Everything is working very nicely. Lines coming soon. Thank goodness for CAD !

 

John

Edited September 26, 2015 by JohnE

[druxey]

'Exciting' might be one word for it, John! Never make a thing simple if you can make it complicated.... Woof, indeed.

[JohnE]

Truer words were never spoken, druxey. I've been trying to model the stern (estain and ecussons) in 3D and then identify a plane and rotate things so they are rectilinear and I can take offsets. Woof ! Painful ! So I was rereading Vial and rediscovered the rest of his entire section on designing the stern. Was so intent on the wonderful hors-d'oeuvres, or the fish entrée, I neglected the perfectly cooked leg of lamb, plat principal.

There's lengths, angles, detail up the wazoo, along with a nice description as to how it will project on a 3-view and an even nicer description as to the effects on a ship's lines by moving certain of the marks in-or-out, up-or down, fore-or aft.

 

Dude, can you say Homer Simpson moment? Du' Ohh !

 

Moving along, Vial's stuff is for a 74, but the concept is still good for a frigate with some adaptation as to to scale. Will be paying more attention to Monsieur Vial in the future.

 

John

[druxey]

Oh, excellent! Much more filling than an amuse-bouche! Bon appetite, monsieur.

[JohnE]

Horray. Eye patch came off this morning. Can see in 3D again and play with curves and such, so back to work on the lines plans.

 

Never realized how hard it was to get a good sense of drawings with just one eye. Guess that’s why the old-timey pirates like John Silver always lost their treasure, even with a map. Aaarrgh !!!

 

John

[JohnE]

Ok, lines are done. Just have to do one more profile plan with the buttock-bows. These are very useful for planking purposes, but also for analysing the speed/length ratios, if you are looking at these hull forms with a modern naval architectural eye. Chapelle gives an excelent take on straightness of buttock-bow lines when crossing LwL. Given our modern understanding of form induced turbulence, he found a shorthand for a first-order rule that satisfies Froude very nicely.

 

Druxey - You asked about this a while back, so the very lazy s curve in the aft end of the profile plan is the aft edge of the fashion piece when viewed from right orthogonal to Mr Keel. The angled lines, aft, in the top-down plan view are the cant-angle lines for the center of the fashion piece; viewed vertically, it is a canted frame, viewed horizontally, it defines a double curvature lazy s. Plot this puppy on a body plan (or even think about it for a second) and you will quickly understand why that last little curve, in the aft body plan, isn't a 'station', but a "projection" of a rotated/canted compound curve. Woof !!

 

[ed] Oops, noticed a blivet. Replaced the drawing with the correct one. The 5th and 6th diagonals (4e and 5e lisses) were adjusted to terminate on the wing transom rabbet. Another Homer Simpson moment.

 

John

Edited October 22, 2015 by JohnE

[malachy]

Quite an interesting and helpful line, that.

 

Here´s what it can look like in 3D:

 

 

 

Not canted the right way at all areas and too thick but it should be helpful to unterstand the concept.

 

[...]and these two ships exhibited such superior sailing qualities that Cornélie was subject of several sailing trials [...]

 

Just noticed this in the first post. Are the 'superior sailing qualities' described in detail?

Edited October 21, 2015 by Bava

[JohnE]

Bava. You have the right idea. Looking at it in 3D is definitely a good way to go. Pictures are indeed worth many words. Vial's drawings, in posts 41 and 47, are very good, but the ability to rotate an object and visualize in 3D is often priceless. He should have taken the oportunity to upgrade to TurboCAD 18 at the special introductory price   .

 

There are several pages of sailing qualities description in the Cornélie devis, but I haven't slogged through all of it, just hit the high points. Her captain, Villemaurin, was apparently a superb example of a highly trained, experienced, intelligent, and scientific sailor. He set up the trials to gauge performance at various trim and loading conditions. The devis has Sané’s tables of the conclusions, with marginal notations. Villemaurin also messed with rake and sail combinations but, unfortunately, his tableaux des voiles has not come down to us.

 

Under best conditions of trim and load, she was quick in stays, neither griping nor making undue leeway; her roll was slow and relaxed (not stiff) but not too deep (not tender, either) making her an excellent gun platform. She wasn’t exceptionally fast at any point of sail, but she was ‘more than adequate’ at all of them. She was very weatherly in all breezes up to a ‘strong breeze’ (because everyone had different words for wind strength, I’m using Beaufort’s description of 1838 – strong breeze, 22 – 27 knots, i.e., force 6). Up to 25 knots, she held her gunports high and did not ‘wet her wales on the roll’.

 

The sense I get is that, when correctly trimmed, she was quick, lively, and responsive in every degree. She had no blemishes. A sleek, lithe, graceful, beauty that Villemaurin loved and caressed and made into a swan.

 

Sorry, got carried away there.

 

John

 

btw, edited the drawing in post 50, and made a note therein.

Edited October 22, 2015 by JohnE

[JohnE]

I’m satisfied with the lines, so off to part deux: disposition of frame.

 

First though, I want to put the outline of the stern elevation on the body plan and add the stern pieces/outlines to the half-breadth plan, but I’m afraid of making them too busy. There’s a ton of extraneous lines/marks on them already. Am thinking of just doing a simplified, curves only, body plan with the stern elevation outlines. Same with the half breadth; I’ll reproduce it up to the aft maître and only show half the waterlines. That should keep things clean enough for the stern portions to show up clearly. Ya’ll think that’s ok?

 

My artistic skills are somewhat (totally) deficient, so the stern elevation will be empty. The wood between the windows is carved as roman columns, I can do those, but you must imagine some fancy scroll work below the windows and a spray of open rose buds along the horseshoe.

 

That won’t take long, so I’ll work on it in tandem with the disposition of frame. When I get bored/frustrated with one, I’ll just switch off.

 

John

[JohnE]

Darn. Drafting your own plans is a bit like working with the wood. The plans have to conform to the wood, so one has to leap a year or two into the future and visualize the finished piece of wood in order that the plans make sense, practically and not just theoretically; model ship builders want to build a ship, not design it.

 

Back in the period, yards would lay the keel, the stem, stern post, and perhaps the maître couples and a few others so they could set the ribbands and such, but the true birth of the vessel was the erection of the stern. Ed Tosti calls this the most complex/troublesome but most fundamental structure of a ship. He isn’t kidding.

 

The stern “space” is defined by three, or more, unintuitive lines in contemporary French plans. A few designers drafted buttock lines, but most did not. They relied on the shipwrights using historical, contextual, experience, as expressed in the many treatises and text books of the period. The problem for this portion of the project is in drafting/extracting/reproducing an accurate set of buttock lines such that they might be combined with the other “aspect” lines of a draft and get a good, accurate, outline (with bevels) of the stern pieces – fashion frames, filling transoms, and the like.

 

If I can do this to my satisfaction, I will be very pleased. Don’t think there’s anything else that will present such a big speed-bump (except for the pretty, artistic, carving stuff), so this will be my total captivation for a while.

 

John

[JohnE]

Whoah, now this is cool.! On the left is the body plan for La Virginie, taken by Portsmouth Dockyard soon after her capture in 1795 (signed by John Marshall, dated 1796). The center image is from the Rochefort plan of La Justice (looking more and more as the poster plan for Sane’s 1810 Reglement). The right side is Armide, laid down 1813 and finally launched in 1821 at Toulon.

 

 

Some really serious comparisons are in order, here. Justice and Armide body plans aren’t far off. When compared to Virginie, one can see the aft frames, after station 7 taking a more relaxed aspect. Woof !! drafting lines to ‘plans’ is an exercise in frustration.

[JohnE]

More progress. Working on the profile plan and have decks (red) and gunport lines (blue) pretty well done. Am working on the hanging of the wales and the profile of the quarterdeck rail. Got a good start.

 

Added an outline of the stern detail to the profile plan. Angles and mulion placements are as per the specification and plans. Imagine my "war whopt, fist pumping air, God, I'm good, Antler Dance" when the decks and everything came together within a half inch (French). Yes I know, I have to tweak the tops of the lines in the body plan to be self consistent. Wayne Kempson reminded me how to do that. I owe him a lot.

 

 

Happy days. John

[druxey]

Moins que un demi-pouce? To that fine a tolerance? That is truly impressive, John!

[malachy]

Impressive, indeed!

 

Looks like the plan is coming along nicely, citoyen JohnE

[JohnE]

Thanks all for the likes and comments.No one was more surprised than I at the result.

 

Here's a bit more progress; hung the top of the wales, and put in the sheer, waist, and the two quarterdeck, drift rails (did the forecastle drift, as well). Beginning to look like a ship, now.  John

[JohnE]

I don't know if this is appropriate on the forum, if not I sincerely apologize. But since this is a French oriented thread, I simply had to say to all my French friends:

 

Moi aussi je suis Paris.

Moi aussi je suis Charlie.

 

Dieu accordera le droit. Dans la tristesse et le plus grand respect.

Dieu vous donne la paix en cette période troublée

 

John

 

[ed] redid this in the right thread. Thanks for the heads up Mark.

Edited November 16, 2015 by JohnE