Vasa 1628 – engineering a ship

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And yet another great video to show. It will be particularly appreciated by users of the Unimat 3 lathe with its original, rather unsuccessful, power transmission system. As can be seen, I converted the whole thing to use toothed belts, instead of smooth belts that slipped and tore quite often. Enjoy!


View attachment Unimat 3 modified.mp4

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-Waldemar- said:
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Hi Renato, I'm not sure it actually makes sense to carry out stability calculations for Vasa 1628 as it was actually built. But that is, of course, your choice. The thing is that this ship was ultimately built to proportions that are grossly inconsistent with the practices of the time, as known from contracts, specifications and recommendations of the era, so the results will not be authoritative at all in the sense that they cannot serve as a useful reference to other designs of the period. And the fact that Vasa 1628 was not (laterally) stable is known, after all, even without the relevant calculations.

If I may make a suggestion, I propose to make such calculations for other ships built in the North Continental/Dutch tradition from a slightly later period (because original plans from this somewhat later period have survived). Moreover, for already matured, dedicated warships, as opposed to merchant or rather in a sense experimental vessels like the Vasa 1628. It would be particularly interesting to see the results of such calculations for a frigate by Pierre Chaillé from 1686 or a 72-gun ‘frigate-ship’ from around 1700 (links below).

French heavy frigate of 1686 – designing a ship in the Dutch manner

. This plan of a heavy frigate, drawn up by the French shipwright P. Chaillé in 1686, is a real gem. First of all, until now it was virtually unknown what conceptual methods were used on the Atlantic coast of France (Ponant) until the very last years of the 17th century, that is, until the...
shipsofscale.com

The Dutch 72-gun ship ca. 1690 – the apogee of Dutch ship design of the Classical Age

. It should be clarified at once that this plan, tentatively dated by me to the end of the 17th century, is one of the last of the era before the widespread adoption of design diagonals, which in the Netherlands occurred in the third decade of the 18th century at the latest (see as to this Ab...
shipsofscale.com


There is a specific reason to verify the lateral rigidity of truly dedicated warships built à la hollandaise. Well, in many period paintings by considered to be the most meticulous artist-painters such as van de Veldes, these warships are often so deeply immersed in the water that the gun ports appear to be above the surface no more than about the height of the gun ports, i.e. only, say, in the range of about 2.5–3 feet, sometimes perhaps even less. Was this because the Dutch-designed warships of this period were particularly laterally rigid, despite the fact that the hull forms of these already dedicated warships were actually quite sharp and do not seem to have any particularly large reserve of underwater volume to reinforce lateral rigidity, as is the case with merchant ships? Or perhaps is it more the effect of artistic license?

Besides, although a 3D scan of the Vasa 1628 has been admittedly made, it is highly unlikely that you will get anything of the sort, as there is a strong general tendency or custom among the professional researchers and archaeologists involved to keep the collected data or preserved artefacts for their exclusive use, at least so long until a relevant publication is made to their credit. For example, research-worthy contemporary ship models, critical graphic documentation produced during the excavations or 3D scans may be kept in semi-private offices or computers for many years under the pretext of being studied, with accompanying declarations of intent to publish their results in the more or less distant future, but the net outcome is that direct access to these data is usually denied or at least very difficult to anyone else. I have personally come across a number of such cases.

Back to the point. On the left you can see one of the many examples of the very short distance of the gun ports from the water (Gouden Leeuw by Willem van de Velde), and on the right the inclination of the ship, which would clearly put such extremely low gun ports under water (Hollandia by Ludolf Bakhuizen). Don't you want to investigate this very phenomenon?


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Hi Waldemar,
thanks for your reply and for the interesting advice.
In fact I was thinking of studying the behavior of ships of this type at high inclinations. I know that the Vasa is not a reference but, given the particularity of the case, I have been guided so far by curiosity. I was wondering if it was possible to definitively exclude for the Vasa the case of an alist ship (that is, for those who do not know, that case in which the ship, although initially unstable, returns to having a positive restoring moment for further inclinations. Simplifying, the ship tends to float permanently list), net of, I would believe, a fatal defect in the positioning of the gun ports.

At this point, however, I would say that given the high degree of uncertainty, perhaps it is better to fall back on other ships. It probably makes little sense to even try to correct the shape of the stations following the indications contained in Witsen's treatise.

Regarding the question you asked, I should actually take a closer look at the characteristics of the ships you showed me, but I wouldn't be surprised to see poor stability even for these. In order to ensure a certain resistance to heeling, in fact, it is necessary that the weight of the ship is distributed low down as much as possible, in addition to having a large waterline and a large reserve of thrust. Therefore, compared to a merchant ship, for a warship of the type mentioned above I would generally expect both worse stability and worse buoyancy. I hope I have been exhaustive!

Renato
 
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Renny said:
Regarding the question you asked, I should actually take a closer look at the characteristics of the ships you showed me, but I wouldn't be surprised to see poor stability even for these. In order to ensure a certain resistance to heeling, in fact, it is necessary that the weight of the ship is distributed low down as much as possible, in addition to having a large waterline and a large reserve of thrust. Therefore, compared to a merchant ship, for a warship of the type mentioned above I would generally expect both worse stability and worse buoyancy. I hope I have been exhaustive!
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Yeah, my earlier assessment based on visual observation alone is pretty much the same. That is why I put forward the idea of computational confirmation, or actually more so — an attempt to quantify these properties.

Please let me know if you decide to do this, and actually when/if you get concrete results. I guess the hardest part will be assigning the correct weights and their computational position for the different components of the ship, but that too can be found in the literature of the period.

Good luck, Renato!

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