The French 1st Rate Ship by Laurent Hubac 1679 — procuring a fleet for the Sun

[-Waldemar-]

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This is a pioneering undertaking of sorts, as it concerns what is probably the oldest technical plan of a French ship (actually a battleship design submitted to the authorities) by the highly productive shipwright Laurent Hubac, who, of all the other shipwrights, built probably the most ships for Louis XIV's so-called first fleet, and to my knowledge, no one has yet made a (correct) conceptual reconstruction of this 1679 design.

The relevant explanations by Jean Boudriot, in my opinion the best expert in this particular field, i.e. historical naval architecture, do not cover this early period, as they only begin with the first decades of the 18th century, being based on written sources that appeared only at that somewhat later time (omitting the ‘age-old’ Mediterranean method, irrelevant in this context, and called by the French the méthode de maître-gabarit, la tablette et le trébuchet). The results of similar attempts at reconstructing ships from this period by Jean-Claude Lemineur, author of otherwise excellent monographs on ships from this period, are not convincing, nor are the explanations in a recent archaeological monograph by Texas A&M University Press on the French ship La Belle 1684, i.e. from the very same period.

The conceptual method found in this project seems to be the same as the one I have already described in threads on this forum concerning Dutch ship designs from about the same period, more specifically, a variant involving the formation of frames using conical curves.

The results of the conceptual reconstruction are the hull lines of Hubac's ship project, presented in the renderings below. The very sharp lines of the hull are striking, especially for such a ‘heavy’ capital ship, as is the fairly pronounced sharp bulge in the central part of the hull at the junction of the bottom and the side, quite resembling a feature characteristic of Dutch shipbuilding (Hubac himself was of Dutch origin).


Waldemar Gurgul


Original plan from 1679 by Laurent Hubac (French archives):

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Reconstruction graphics:

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[-Waldemar-]

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For the sake of completeness, it is also worth presenting the design of the 50-gun ship Neptune (French archives), also from 1679 and by the same designer, Laurent Hubac. As already mentioned, these are the oldest extant technical plans of French ships. However, due to a lack of understanding of ancient design techniques, both of these plans were not appreciated by modern authors and for this reason have been simply disregarded or being commented as clumsy, primitive sketches that have little to do with ship architecture in the full sense of the word.

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[Martes]

I suppose the second plan is also sufficient for reconstruction, despite the lacking top view design line?

 

[-Waldemar-]

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I suppose the second plan is also sufficient for reconstruction, despite the lacking top view design line?

That's right. The contour of the line of the floor in the top projection can be easily reconstructed based on coordinates taken from the master frame, both quarter frames and both posts (all of these on the draught). All it takes is to connect these coordinates with arcs, and you can't really go wrong. This is how the line of the floor was defined in that era — just using these very coordinates, and this is how it is recorded (and mandated) also in the royal decree of 1673.

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[Martes]

The shape of the stern lines, with a very sharp turn downwards and straight lines forming a triangle with the keel -



I remember relatively similar line on the plan of Le Prompt as taken



Is it connected somehow with flat tuck stern or just some kind of design style?

 

[-Waldemar-]

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Yes, I believe that the specifics of both cases you show above are closely related, as both result from the same geometric imperatives. More precisely, at this place on the hull (i.e. for the location of the fashion piece), the lower parabola of the frame contour should have the shape shown by the red solid line (see graphic below). This course is consistent with and directly results from the entire geometric structure of the design. However, below the fashion piece itself, the contour of this last ‘frame’, treated as a whole, obviously cannot cross over to the other side of the plane of post, therefore the lower part of the lower parabola is replaced by a straight line (red dashed line). This also affects some of the other, last frames, hence the characteristic flatness of their contours in their lowest parts and quite sharp turn downwards, as, seemingly, in Le Prompt.

This sharp junction at the height of tuck can, of course, be ‘softened’ with an additional small arc, but in fact the effect of such a measure would probably be more aesthetic than practical (e.g. some noticeable improvement in hydrodynamic properties).

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[Hubac’s Historian]

I’m very excited to see your work on this subject, Waldemar. At this time, would there have been a notable increase in draft toward the sternpost, or would the waterline have been almost parallel to the keel? The difference seems slight, but your rendering does appear to indicate a more shallow draft at the bow.

 

[-Waldemar-]

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Hi Marc, thanks . Below is my conceptual interpretation of Hubac's design with its most important elements and some dimensions, and there is also a reconstructed waterline (admittedly, the original plan does not contain any direct information relating to this specific element). It should first be noted that typically in Dutch plans from around this period, the keel is horizontal, while the longitudinal design lines are oriented according to the inclined waterline, making it relatively easy to find the trim even without direct data of this kind. Here, however, the longitudinal design lines are oriented according to the horizontal keel, which may suggest a lack of trim, or that the designer deliberately did not take the trim into account while plotting design lines, or is just a simplification of the drawing.

Ultimately, in my interpretation of the missing waterline here, I have opted for a fairly typical distance of 3 feet below the maximum breadth line for the „midship” frame, resulting in a gunport height of 5 feet above the water at this part of the ship. I have also given an equally typical two-foot trim — that is, plus about 1 foot for the stern and minus about 1 foot for the bow. However, if anyone disagrees with this, they can of course apply their own ideas .

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[Hubac’s Historian]

Thank you, Waldemar, for the clarification.

 

[Martes]

which may suggest a lack of trim, or that the designer deliberately did not take the trim into account while plotting design lines, or is just a simplification of the drawing.

It is worth nothing that finding an ideal waterline for each specific ship took practical experimentation, and it could be different from what the designer intended. The British reports for late 18th century often suggest that French ships were best at even keel, for example, but most of them were certainly designed for being trimmed aft.

 

[-Waldemar-]

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In the context of the waterline, and precisely of its design height, it is worth pointing out an interesting provision (requirement) from the royal decree of 1673, which is closely related to this issue. Literally, according to this provision, the maximum breadth line should be at the planned height of the water line, and as a result — the opposite should also be true. However, this very provision, taken too literally, seems absurd for warships, and even for two reasons.

Firstly, from a hydrostatic point of view, such an arrangement would effectively annihilate the ship's transverse (so-called shape) stability. Secondly, considering that the main gun deck was usually located just at the height of the line of maximum breadth (as is the case precisely in this particular design by Hubac from 1679), or very close, this would translate into the height of the gun ports above the water of only two feet! It follows that this specific requirement from the royal ordinance simply could not be applied in practice.

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