Waldemar

Bravo!

Grazie per questa fotografia. Le linee di prua di La Néréïde si vedono molto bene. Perfetto. Thank you for this photograph. La Néréïde's bow lines can be seen very well. Perfect.

Why not stop building the model at this stage? 🙂 Such beautiful shapes...

I have the irresistible impression that it is your model that most resembles the originals. More so than those with perfectly smoothed lines from the age of computers and industrial robots.

This is actually a series of publications: The Mariner's Mirror Volume 107, 2021 - Issue 2 A Restoration Yacht’s Design Secrets Unveiled: An examination of a ship model with reference to the works of William Sutherland Effie Moneypenny & David Antscherl Pages 164-187 The Mariner's Mirror Volume 104, 2018 - Issue 2 A Model of the Royal Yacht Henrietta about 1679: Description and identification Effie Moneypenny & Simon Stephens Pages 172-191 The Mariner's Mirror Volume 102, 2016 - Issue 4 The Royal Yacht Isabella of 1683: Identification and principal dimensions Kelvin Moneypenny & Dorin Paul Bucur Pages 400-416 The Mariner's Mirror Volume 100, 2014 - Issue 2 The Royal Yacht Henrietta of 1679: Identification and principal dimensions Kelvin Moneypenny & Dorin Paul Bucur Pages 132-146

Being fresh from reading a very interesting publication on the Restoration yachts of Charles II, I looked again at William Sutherland's work, The Ship-builders Assistant, 1711, focusing on his method of shaping ship hulls. In his work, Sutherland proposes shaping ship hulls so that the submerged part of the hull takes the form of an (elongated) egg. Such a shape is called a conoid. Both the characteristic feature and result of such a form are frames with the profile of a perfect arc (connected by an additional line(s) to the keel and the posts). In addition, the radii of these arcs are different for each frame. The very idea of using variable radius arcs for different frames was not entirely new at the time. Anthony Deane (1670) had already partly used this way to construct the profile of the frames (although not in the textual description, but in his drawings), the way described in the work of Georges Fournier (Hydrographie, 1643) can also be interpreted in this way, and there is a plan of the English origin in the Russian archives, in which the arc of the greatest breadth is based on the principle of variable radius (the plan is undated, but the ship has clear features specific for the turn of the 16th and 17th centuries, in particular the square-tuck stern and the considerable rakes of both posts). Below I have shown my graphical interpretation of the method proposed by Sutherland. It should be stressed here that the original plan has some drawing anomalies and, moreover, does not quite match its textual description, so reverse engineering methods were also necessary to interpret it. As can be seen, the conoid is only the body defined by the upper arcs, while the floor curves (also called hollow lines, bottom curves etc.) were constructed by Sutherland in the conventional way. Here, too, it must be added that Sutherland chose one way of drawing the floor curves in his drawing, while in the textual description he proposed a different method for use in the actual construction of the ship in true scale, but still using a simple template made of only two parts: a line and an arc. As a result, the theoretical shapes (as in the plan) and those of the actual ship had to come out slightly different.

Have just read the paper on the reconstruction of the hull lines of Charles II's yacht. An exciting read, but I must also admit that I would have had a few comments and my interpretation of some important issues would have been different.

Yes, the end, but only the original plans, because I also want to show another way of constructing the bow curve shown in the work of Jean Boudriot, Les vaisseaux de 50 & 64 canons. Étude historique 1650-1780. This method must come from the 18th century French works on naval architecture (I should verify this, but I didn't for the sake of saving time). This way is quite complicated, and also for special cases where the bow curve in front view is a segment of line inclined at a certain angle, as can be seen in the attached scan below. It is shown here rather for completeness, as for all above reasons this way was not suitable for my purposes. Furthermore, the resulting curve shape is not quite decent and at the same time not the easiest to modify. The method as shown visually in Jean Boudriot's work:

F I N

1692 – Le Royal Louis: 1720 – Le Sceptre:

1690 – Le Laurier, 64 guns: ca. 1690 – barque longue:

1685 – fluit (note: distorted and uncorrected plan): 1686 – frigate of the 1st class:

ca. 1680 – 52-gun ship: ca. 1685 – 58-gun ship:

I decided to check more early plans of the French origin for the shape of the bow curve. Specifically, how often logarithmic curves were or may have been used to create them. 1679 – Project of a 1st rate ship of the line: 1679 – Le Neptune, 50 guns:

I only have quick access to issues of the Mariner's Mirror up to 2000, but I have just located newer issues in my local library 🙂. Going there soon to pick up this article and after reading it, everything will be clear. Thanks again for this reference.

I would have to look at Sutherland's work again, and also read the article you provided. Now, after your latest post, I am assuming that the method you refer to, gave a profile of the various frames consisting of just one arc, but of variable radii (plus, naturally, a hollow/floor curve), as in the Sutherland's work. Indeed, of extremely elegant simplicity in an engineering sense, and giving visually elegant shapes. For these reasons I wanted to use it in my reconstruction, but in the end the 'classical' method prevailed, very widespread and known for centuries for sure, in which a few templates/moulds were used to geometrically determine the contours of all the frames. That is, the radius of the respective frame arcs was constant all along the hull length (in effect, the 'hauling futtocks up/down' method).

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.

Lovely. You are truly a professional shipbuilder.

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.

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.

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...

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?

Yep, for CAD work only Rhino and I like it very much. Of course, my renders were only to show the idea of the proceedings, you choose the exact shape.

Or, when exporting pages from a PDF document as bitmaps, set higher resolutions.

The size of the inserted bitmaps into the posts is reduced (probably to a maximum of 1440 pixels of the longer side). Yes, these are quite nasty shapes to model, but possible. Try it this way, but your initial polysurface needs to be closed (for better clarity and less working time a straight element in this sample): This is not the only way, but probably the most convenient.