Waldemar

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.

Fantastico. La disposizione dei telai nel suo modello è quasi identica alla mia ricostruzione, con l'unica importante differenza che nel suo modello le singole costole sono costruite come un unico pezzo dalla chiglia fino all'estremità superiore, mentre nella mia ricostruzione i legni superiori sono "galleggianti" liberi. Mi riferisco a una nave dell'inizio del XVII secolo. Fantastic. The arrangement of the frames in your model is almost identical to my reconstruction with the only important difference that in your model the individual ribs are built as one piece from the keel up to the very top, while in my reconstruction the upper timbers are 'floating' free. I mean a ship from the beginning of the 17th century.

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.

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.

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.

In May 1626, the under-armed and undermanned Western Squadron from Götheborg was redeployed to the main fleet base in Stockholm, where ships were prepared for the coming war.

🙂 By 1625 part of the Swedish fleet was at peace footing, so crew shortages were not a problem and even an advantage (money!), until mobilisation in 1626 for a massive sea-borne invasion of the southern Baltic coast. I have found these documents, some 12-13 years ago, while looking for information on the Solen, the Swedish ship originally in the same group with the Papegojan, based in Götheborg. Just went to archives in Stockholm (Krigsarkivet and Riksarkivet), and bingo! Unknown and previously unpublished material. 🙂

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.