Bow shape of Le François 1683 and La Néréïde 1722

[Waldemar]

 

The monography of the French frigate La Néréïde 1722 is now being in preparation by the author of many other fine monographs – Jean-Claude Lemineur, and of my utmost curiosity is the exact way the shape of La Néréïde's hull was reconstructed by him. It should be noted that the source plans do not include a line plan of the entire hull, only the profile of the main frame and the longitudinal shape of the vessel. In parallel with the creation of the monograph, an attractive model of the ship is being built by Michele.

 

While it is not quite possible to assess well the hull lines directly from the photos of the model, I get the impression J.-C. Lemineur has taken a similar approach as in his reconstruction of Le François 1683, in which he employed the quadrant type curve for the bow shape.

 

Yet, upon making my own reconstructions, I have discovered that such a curve, while looking good and being very useful for recreating many other parts of the hull, never works satisfactorily for the ships' bows. To put it the other way, it can never be aligned with the corresponding lines in any contemporary ship plans (notwithstanding the many possible modifications of this curve).

 

In turn, the method of deriving this curve shown at the bottom of the attached sketch almost always gives the desired results. This half-distance derived curve can be also modified in many ways to get, say, sharper or blunter bows. Strangely, I have not found this method in any contemporary works on shipbuilding I have consulted, and it was reverse-engineered by trial-and-error.

 

 

 

 

[Waldemar]

 

On 9/12/2022 at 1:00 PM, druxey said:

I understand the generation of the curve aft from '1', but how do you define the curve from '1' to the stem?

 

Good question. Indeed, additional effort is sometimes necessary to get a decent curve.

  

– 1st method: simply approximating by eye (sufficient in many cases and evidently used by period designers; allows a slight, deliberate modification of this curve at the stem area),

– 2nd method: by defining an additional point on the middle line (better explained in the attached sketch),

– 3rd method: by placing the first defining point closer to the stem (the rest of the procedure is the same).

 

And, by the way, the factor can be other than 0.5, yet it is the most convenient number.

 

 

 

[Hubac's Historian]

Okay, all very interesting.  So, when you compare JCL’s curve with other contemporaneous vessels, for which there are lines plans, do you have an example where you can show this discrepancy.  Does the Jazon, for example, have a full draft of lines?

 

Obviously, what you are drawing attention to is an important consideration as it directly impacts the interior layout and functionality of the warship.

[Hubac's Historian]

Actually, just re-reading your original post.  The JCL curve you are referencing is actually for the Francoise of 1683.

 

What puzzles me is that lines plans for this period do not exist.  As I understand it, hull shape was derived primarily from the placement of three frames along the keel; the main frame, a frame forward and one aft.

 

If you have contemporary lines plans from this period, I would love to see them.

[Waldemar]

 

14 hours ago, Hubac's Historian said:

As I understand it, hull shape was derived primarily from the placement of three frames along the keel; the main frame, a frame forward and one aft.

 

Well, in most cases probably yes, depending on the method and assuming we mean early modern area.

 

Simplifying a bit – there were then many methods of deriving hull shapes. They could be graphical or non-graphical (ie. no scale plans were necessary), the ships could be formed and built by shell methods, frame-led methods or skeleton methods. In these methods all, some or no actual frames were pre-designed (i.e. formed before their assembly in the hull structure). And all kind of intermediary ways...

 

There was a very widespread method, in which main frame profile was offset and slightly rotated almost as one entity to get the shape of other frames. This way the rest of the frames could be formed on the shipyard ground before their insertion into the constructed hull. But this was only possible to some point, limited by those two 'quarter' frames. Beyond these 'quarter' frames the hull ends were then usually shaped by using flexible battens.

 

In the early variants of the more flexible 'hauling up/down futtocks' method (in which the main frame shape was divided into several 'independent' geometrical parts) the 'quarter' frames were still being retained, but they were already not really necessary, as in this method pre-designed frames could be usually formed till the very ends of the hull.

 

Those three crucial frames could be also employed in the frame-led method, and nothing more except flexible lengthwise battens.

 

In a slightly later, already fully graphical methods employing geometrical 'battens', these two 'quarter' frames could be dispensed with at all.

 

In the shell methods, these two 'quarter' frames could be equally superfluous.

 

Yet, it is best to consult the sources. For the 16th and 17th centuries I would recommend the following works:

 

– Fernando Oliveira, Livro da fabrica das naos, ca. 1570–1580
– English so-called „Newton” manuscript of ca. 1600
– Manuel Fernandes, Livro das Traças de Carpintaria, 1616
– English anon. manuscript of ca. 1620
– Spanish government ordonances (dimension establishments) of 1607, 1613 and 1618
– Georges Fournier, Hydrographie, 1643
– Bushnell Edmund, The Compleat Ship-Wright, 1664
– Anthony Deane, Naval Architecture, 1670

 

Alternatively, or additionally, the excellent modern works on the period naval architecture by such expert authors like Jean Boudriot, Éric Rieth, Richard Barker, Filipe Vieira de Castro, Alan Lemmers.

 

 

[Hubac's Historian]

Two sources of more immediate connection to French practice in the 1670s/80s would be Album de Colbert and Dassie’s L’Architecture Navale.  I have not yet obtained a copy of the latter, but would be curious to know what, if anything, he has to say about the process of establishing the form of a hull.  Have you read Dassie?

Edited September 14, 2022 by Hubac's Historian

[Hubac's Historian]

I am still curious to know your point of comparison between JCL and specific contemporary lines plans.  You say that the two are incompatible, but how specifically? 

[Waldemar]

 

2 hours ago, Hubac's Historian said:

I am still curious to know your point of comparison between JCL and specific contemporary lines plans.  You say that the two are incompatible, but how specifically? 

 

Preparing graphics takes time, please give me some of it.

 

 

2 hours ago, Hubac's Historian said:

Two sources of more immediate connection to French practice in the 1670s/80s would be Album de Colbert and Dassie’s L’Architecture Navale.  I have not yet obtained a copy of the latter, but would be curious to know what, if anything, he has to say about the process of establishing the form of a hull.  Have you read Dassie?

 

Yes, I have both works in my home library and that's why I haven't listed them above. The Album de Colbert has nothing to do with the concept of ship design, and Dassié's work is very poor in that respect. I have included scans of two plates regarding this issue from his book. There are quite a few oddities in his work and this one is also quite disappointing. I would rather never choose to try to recreate the hull shape basing on Dassié's description.

 

 

 

 

[Hubac's Historian]

I think it is, perhaps, fair to say that the Album describes a step-by-step process, and that process to some degree informs design.

 

As for Dassie, while the illustrations are cartoonish and not to be taken too literally, there does seem to be some effort to apply mathematics toward predictable/repeatable outcomes.  I will have to get my hands on a copy, at some point. 

[Waldemar]

 

1 hour ago, Hubac's Historian said:

I think it is, perhaps, fair to say that the Album describes a step-by-step process, and that process to some degree informs design.

 

As for Dassie, while the illustrations are cartoonish and not to be taken too literally, there does seem to be some effort to apply mathematics toward predictable/repeatable outcomes.  I will have to get my hands on a copy, at some point. 

 

This is not quite my intention to enter the dispute on this now. I will just stand by my opinion.

 

But back to the curve of the greatest breadth at the bow. It is needed especially while trying to reconstruct the hull shape from scratch, and I started the search for a type of curve as employed by contemporary shipbuilders. Its geometrical construction had to be simple, easily adaptable to the non-graphical methods of hull shaping, had to connect the hull station at the ship's greatest breadth with the stem, and to provide a wide range of possible shapes, from very sharp to very full. In short, rather long search in period works for adequate type of such a curve failed, until help came from one of the excellent works on period naval architecture by Jean Boudriot – La conception des vaisseaux royaux sous l'Ancien Régime, Neptunia 169.

 

 

The described method (shown at C above) of creating logarithmic curve seemed feasible, and after its adaptation for my purposes, already first comparisons with period ship plans gave desired results. The first to be checked were draughts made by professional shipbuilder from 'my' period, Portuguese Manuel Fernandes (from his Livro das Traças de Carpintaria, 1616).

 

 

 

 

 

Edited September 14, 2022 by Waldemar

[druxey]

Very instructive, Waldemar! Thank you for that. I've been studying English derivation of ship's lines in the 1680's. Many curves are based on circular arcs, but not all. Some are based on the cono-cuneus curve.

[Waldemar]

 

On 9/15/2022 at 2:42 AM, druxey said:

Very instructive, Waldemar! Thank you for that. I've been studying English derivation of ship's lines in the 1680's. Many curves are based on circular arcs, but not all. Some are based on the cono-cuneus curve.

 

🙂 Thanks. Yeah, I had a meeting with these curves too in Sutherland's The Ship-builders Assistant, 1711. By the way, almost made the frames of my reconstructed ship with variable radius, as he proposes, but finally decided that the turn of the 16th and 17th centuries would be too early for such development.

 

 

 

Before checking the French draughts I have also verified a few early plans of the 'British' origin and found their creators 'cheated' in a sense that they fabricated somewhat pragmatically this bow curve from two or more arcs, not necessarily perfectly tangent. Be that as it may, while this way of doing things was quite acceptable in graphic methods, it was entirely not practical in non-graphic methods, and I had to reject them.

 

In this draught of the English origin of about 1625 (from the Rigsarkivet, Copenhagen), I have also drawn in blue a quadrant type curve. As can be seen, it is completely out of place.

 

 

 

 

Below is a plan of the Danish ship Argo 1599 (Rigsarkivet, Copenhagen), designed by Scotsman David Balfour.

 

 

 

 

Edited September 16, 2022 by Waldemar

[Waldemar]

 

Now we have finally arrived at the plans of Le Jazon 1724, which could probably best be used to recreate the shape of La Néréïde's hull. As can be seen below, the logarithmic curve only partly coincides with the original line, but it must also be added that the French designers were known for their so-called tâtonnement, i.e. modifying the lines manually in various ways. And even despite the lack of complete correspondence with the original curve, even the unmodified logarithmic curve still gives much better results than the quadrant curve.

 

 

 

 

Edited September 15, 2022 by Waldemar

[Waldemar]

 

All this does not mean that quadrant curves could not be used for the bow section at all. They could, and even quite successfully, but only on condition that the bows were very blunt, and the greatest width of the hull was very close to the stem. In practice, for large capital ships and merchantmen. And probably rather by less experienced draughtsmen.

 

Below is an example of such a form of French origin from the late 17th century (from the monograph by Jean Boudriot, Le vaisseaux trois-ponts du chevalier de Tourville 1680) with curves of both types drawn in it. For self-assessment... (it is important to bear in mind that this plan is quite heavily distorted, and I have only made partial corrections).

 

 

 

 

Rather the end, I've already done quite a lot of work on it anyway.

 

 

Edited September 15, 2022 by Waldemar

[druxey]

Thank s for these examples, Waldemar. Would you consider that some of these curves may also have been made using a tapered batten pulled, bow fashion, into a curve?

[Waldemar]

 

Yes, indeed, here are my current views on these tools:

 

Naturally, a great many curves were certainly drawn with flexible chord- or screw-tensioned battens. These are the near-perfect equivalents of today's CAD command: "draw curve through points" – almost indispensable but secondary tools in essence, because useless without predefined points. The use of these drawing aids is not even specifically mentioned in the source works on shipbuilding, in stark contrast to the extensive descriptions of determining the points that define the course of curves, be it by geometrical or mathematical means. To put it another way, these drawing aids were unlikely to have been used independently, i.e. to determine the entire course of the hull curves by eye only.

 

Assuming that these aids always/usually produced smooth curves, they may have been used in the Portuguese and French examples, but not in the 'British' ones because of the scarcely visible details of these curves in the posted scans. In the first, English example, the curve has kinks, non-tangent points and sections of varying curvature. On the Argo plan, most of the bow curve is a perfect arc and only the last part of the curve is straighter. It is clear that in both of these cases the curves were drawn in two or more stages, as they could not have been created with a single tool giving smooth contours. Alternatively, the drawing aids actually used had some defects.

 

But the most important thing from my perspective is that I was looking for a type of curve suitable for use in non-graphical methods of shaping ship hulls, rather than specific tools for drawing curves in graphical methods.

 

 

[Waldemar]

 

Originally, I just wanted to give a final visual demonstration of the concept of the non-graphical method of ship design using the bow curve as an example, but in doing so I probably discovered why, on the French example plans I posted earlier, the logarithmic curves are perfectly aligned with the original bow curves at the front, but do not quite coincide with them at the back.

 

Below is a diagram showing a possible way of tracing the points of the bow curve. The tracing is done immediately to true scale on a tracing platform or other flat surface in the yard. Actually, drawing this bow curve is not needed at all in this non-graphical method, only the points are needed to get the outline of the frames in the next step, and for better clarity there are only five of them in the diagram. 

 

 

 

In the below magnification, you can see that some of the points obtained need to be moved slightly to get a bow curve with a nice contour on the front view. This would explain very well the need for such manual correction by ship designers.

 

 

Why bother with it at all? And yet, along with archaeological finds and general iconography, this is the key to plausible reconstructions of ships from the period of non-graphic shipbuilding methods, or simply where original line plans have not survived.

 

 

[druxey]

It is a fascinating rabbit hole down which to wander!

[Waldemar]

 

Thanks, Druxey. I was already starting to think it was only for geometry freaks. 🙂

 

 

I would also like to add that the problem of correcting the logarithmic curve at the back does not actually occur with a large number of stations, say, equal to the number of frames. Correction only becomes a necessity with a relatively small number of stations, such as on these French plans. However, in the former case, a factor of 0.5 may not be appropriate, and then it needs to be changed to another number.

 

 

 

Edited September 17, 2022 by Waldemar

[Waldemar]

 

This is why I did not recognise this phenomenon earlier, reconstructing my ship straight away with a large number of stations, as in the example below.

 

 

 

Edited September 17, 2022 by Waldemar

[Waldemar]

 

Hubac's Historian:

 

I have just reread the description of the ship's hull shaping given in Dassié's work (most of it). In fact, I was previously too harsh on his description. If you are going to buy this book, expect something very similar in most respects to Anthony Deane's work on naval architecture. Apart from that, you will find a lot more information about scantlings, masting, rigging, nomenclature, even on galleys, and the texts of the applicable Royal Ordinances. You should be much satisfied. What I didn't like about this book was the strange, rather convoluted formulas for the proportions of various ship elements, much more so than in other works.

 

 

 

P.S.

How to properly quote a user's name in the posts?

 

 

Edited September 18, 2022 by Waldemar

[Hubac's Historian]

Do any of those formulas address the shaping of the bow?  Thank you for the insight into this book.  When things settle down, over here, I will pick up a copy.

 

As for user names, I suppose you could insert the user name just as you would their given name.  My name is Marc, so whichever you prefer is fine with me 🙂

Edited September 18, 2022 by Hubac's Historian

[Waldemar]

 

For the sake of completeness, I've also included below a diagram showing the concept of forming ship hulls using mathematical formulas, as described in an anonymous English manuscript from around 1620.

 

Mathematical methods were considered superior to graphical ones because of their greater precision. However, getting the bow curve of the desired shape was too challenging for these mathematical methods, and this very line still had to be corrected manually using the method shown in the diagram (also following the advice in this manuscript). 

 

 

 

 

... on Dassié's way of shaping the bow curve in a while...

 

 

Edited September 18, 2022 by Waldemar

[druxey]

I can't reproduce research from Mariner's Mirror here, but Phineas Pett in the 1670's and 80's had developed a sophisticated method of designing a fair hull - stem to stern - using arcs and a cono-cuneus curve. These were all proportional to the length of keel and moulded breadth. Here is a hull (work in progress) developed by this method:

[Hubac's Historian]

So mathematics gets you close, but the bow shape is still in the eye of the shipwright.

[Hubac's Historian]

Sweet hull, Druxey!  Is this your latest project in development?

[Waldemar]

 

24 minutes ago, Hubac's Historian said:

So mathematics gets you close, but the bow shape is still in the eye of the shipwright.

 

Exactly! Depending on the shape wanted.

 

 

Below is a diagram based on Dassié's description. He takes as an example a ship with a keel length of 115 feet (suitable for a third-rate ship of the line). Unfortunately, this is probably the weaker part of his work, as the formulas he gives cannot be taken completely literally, and the lines have to be corrected to get decent contours. As you can see, the line of the breadth obtained by his method has a kink at the main frame, and its forward course is already completely unacceptable (in red, I have added by eye a bow curve with a somewhat better course). As a result, despite the plausible concrete dimensions, the ways he gives should rather be perceived in a demonstrative manner.

 

And just to clarify that the same defining lines (horizontal) are used equally for the bow and stern sections.

 

 

 

 

[Waldemar]

 

1 hour ago, druxey said:

I can't reproduce research from Mariner's Mirror here, but Phineas Pett in the 1670's and 80's had developed a sophisticated method of designing a fair hull - stem to stern - using arcs and a cono-cuneus curve. These were all proportional to the length of keel and moulded breadth.

 

Both the build quality of the model itself and its lines very attractive 🙂.

 

 

I must admit that I am not familiar with this publication in Mariner's Mirror, but for those interested there is also a very good chapter on ship design by John Shish in Richard Endsor's modern work, The Master Shipwright's Secrets. How Charles II built the Restoration Navy.

 

 

[druxey]

Moneypenny and Antscherl, A Restoration Yacht’s Design Secrets Revealed, Mariners Mirror, Volume 107, Issue 2, May 2021.

 

Yes, Hubac, the model in the photo is the result of the article quoted. No fudging required at the bow!

Edited September 18, 2022 by druxey

[Waldemar]

 

Many thanks Druxey for pointing this publication.

 

Methods using conoidal curves were among the most sophisticated of their era and could certainly only be used by a select few, the most accomplished designers. The approach to my reconstruction had to be quite the opposite – to find the ways as simple as possible, suitable for use by 'any' shipbuilder using non-graphic methods. Finally, I have adapted the practical method described in the extremely popular at the time work by Bushnell. Very many editions of this book emphatically testify to the fact that common builders tended to be content with such methods, which were as simple as possible. And then I mixed it with dimensions, proportions and scantlings taken from inventories, contracts and other works on period shipbuilding.