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William Sutherland's concept of ship hull design, 1711


Waldemar
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From my observations, the simplest possible explanations and methods are usually correct. In post #9 you will find my brief interpretation of this phenomenon, and after every hull I draw I am more and more sure of it. On the surface it may seem that the method of drawing used by designers or draughtsmen is longer and more difficult, but in fact the opposite is true.

 

If you do drawings, whether by hand or computer, you can check this for yourself. Try drawing a few frame profiles using both methods, and for this exercise you may follow Sutherland's instructions shown in this thread. You will find that it is much more difficult and longer to draw the shipyard profiles that were obtained with wooden templates – it's endless fitting by trial and error. In this light, it is clear to me that the designers actually used shortcuts to speed up the drawing. In contrast, it was much more convenient and quicker to use wooden templates in the shipyard.

 

To put it another way, it was a kind of drawing convention, and 'everyone' knew that the floor/hollowing lines would only be finally formed on the mould loft in the shipyard. As is clear just from Sutherland's description.

 

 

The shape of the ship you posted above gave me a good laugh.... 🙂  What an imagination!

 

 

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There were other strange - to us - underwater body shapes. Another example is Inspector of 1782:

 

https://commons.wikimedia.org/w/index.php?title=Category:Ship_plans_of_the_Royal_Museums_Greenwich&filefrom=INFERNAL+1815+RMG+J7573.png#/media/File:Inspector_(1782)_RMG_J4476.png

 

showing the hydrodynamic lateral fins in the aft body. It was not repeated, so presumably was not successful in controlling roll.

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Unfortunately, there is no indication of the experimental nature of the Danish ship. On the contrary, her very long, intensive and successful service (about 40 years) also rather proves that this is not some kind of experimental, bizarre fantasy, mostly unsuccessful. Instead, there is Sutherland's work explaining this phenomenon very convincingly. So personally, I see the Danish ship as a 'standard' vessel, just like 99.9% or tens of thousands of other vessels.

 

I guess a good analogy is the simplistic, common way of drawing threads in modern engineering drawings, which does not show their true outline at all. Today it is common knowledge that this is just a drawing convention to save the draftsmen time, but what about the interpretation of such drawings by archaeologists five hundred years from now? 🙂

 

 

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Respectfully, Waldemar, I'm not sure that I agree with your suggestion that ships, as built, varied in shape from the draught other than by perhaps an inch or so. If one plots out proof diagonals, they usually produce a nice smooth, faired line. Here I'm talking about British draughts, as I've not extensively studied Continental ones.

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12 hours ago, Waldemar said:

You will find that it is much more difficult and longer to draw the shipyard profiles that were obtained with wooden templates – it's endless fitting by trial and error.

Surely the designer would provide some documentation to the shipyard?

 

There are many relatively complex shapes recorded in "as taken" plans of captured French warships from 18th century in Admiralty archives.

 

See La Prompt, 1702 (earliest recorded prize, I think):

 

An image showing 'PROMPT PRIZE 1702' https://collections.rmg.co.uk/media/2/441/682/j6131.jpg

 

https://www.rmg.co.uk/collections/objects/rmgc-object-87615

https://www.rmg.co.uk/collections/objects/rmgc-object-87616

Edited by Martes
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To be honest, I don't see any contradiction in our statements, and the answer to this kind of doubt is probably also simple: around the turn of the 17th and 18th centuries there was a change in drawing convention to a more precise one, with Sutherland still representing the old school. And I remind that the Danish ship was built 1665.

 

There is no doubt that ships could have been built according to plans (with some reasonable tolerance). On the other hand, we have 'countless' examples of ships built for the Navy, especially by private shipyards, oversized by 5, 10, 15% or even more in relation to their design (largely for financial reasons), so the differences must have been counted in feet rather than in inches. These were accepted, paid for and successfully put into service.

 

 

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1 hour ago, Martes said:

There are many relatively complex shapes recorded in "as taken" plans of captured French warships from 18th century in Admiralty archives.

 

See La Prompt, 1702 (earliest recorded prize, I think):

 

I am not sure that the example with the French ship is quite relevant. This ship was built by the designer René Levasseur in 1692. By this time, the French shipbuilders were already using newer design methods, using geometrical diagonal lines, unlike the British, who were still using one frame-moulding variant or another for quite a long time.

 

Firstly, as can be seen from the drawing, the lines of the French ship were reconstructed in the British fashion (frame-moulding), so it is certainly not an accurate representation of the hull shape.

Secondly, the problem of bottom curves was solved in a completely different way in the French method, but that's another story....

 

 

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As far as I remember, the "as taken" plans were taken by measuring a number of points along the frames (with or without planking, depending on the depth of refit the ship was undergoing) and connecting them. I definitely remember somewhere this process was described in detail, and that with planking stripped it should have been more or less reliable form of recording the ship as actually built. It is possible they put some additional reconstruction along the way, but still.

 

By the way, is it possible to tell if La Prompt had square or round-tuck stern from?

 

But what nags me with the Danish ship (by the way, was she built by private or government shipyard?) is that the designer certainly meant something with the inward arc, and it's very difficult to imagine it was negated just like that.

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59 minutes ago, Martes said:

But what nags me with the Danish ship (by the way, was she built by private or government shipyard?) is that the designer certainly meant something with the inward arc, and it's very difficult to imagine it was negated just like that.

 

The Danish ship Prins Christian (renamed 1673 as Christianus Quintus) was built on contract at the Neustadt shipyard.

 

Sorry, but if the content of this thread so far is not convincing enough, it remains to refer to Sutherland's original work. I may find some more examples, but by accident rather than by deliberate search.

 

 

59 minutes ago, Martes said:

By the way, is it possible to tell if La Prompt had square or round-tuck stern from?

 

The copy of the plan of the French ship made available is quite poor and the lines are not quite clear. Anyway, just a note here that this was a transitional period in France at the time as far as the shape of the stern is concerned and it may be some strange hybrid. Why not try to interpret this shape yourself?

 

 

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On 9/23/2022 at 11:42 PM, Waldemar said:

After reading a number of works on naval architecture, I get the impression that constructing floor curves was a routine procedure used by ship carpenters. And for this very reason the early designers and writers simply did not bother with it. In one of the source works, for example, one can literally read (from memory): "the floor curves are left to the discretion of the actual builder". 

 

I think I have missed this point.

Still, it's something very puzzling.

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1 hour ago, Martes said:

Still, it's something very puzzling.

 

In fact, I do not insist on accepting or confirming this interpretation. But the mere awareness of such a possibility might just come in handy for you while potentially inspecting some period plan.

 

 

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5 hours ago, Martes said:

Yes, it's very revealing about the practices of the time. 17th century was very different from 18th

 

True. As an example of a ship drawing from the 17th century, I still include below a plan of a yacht from 1665, which was built at the Götheborg shipyard by an Englishman, Francis Sheldon. This is the oldest extant ship plan in Sweden showing the profile of the frames (stern only). As you can see, the drawing standard is still far from the precise 18th century convention (Swedish archives).

 

I will no longer carry out a reconstruction of this shape, but the frame profiles indicate quite clearly that the designer used the conventional frame-moulding method.

 

image.thumb.jpeg.35c8316d3bab434fa110ba21a0bada09.jpeg

 

 

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In addition, and for comparison, another design drawing made around 1660, but this time by an equally professional shipbuilder Jakob Jakobsson Prunk of the Dutch origin. Frame profiles were not needed in this case at all, as this 18-gun frigate was most likely to be built in the Dutch fasion, i.e. by the shell (bottom-first) method.

 

But again, look at the draughtsmanship standard (Swedish archives).

 

image.thumb.jpeg.79540413df0027ecdc68f05ce62496f7.jpeg

 

 

 

Edited by Waldemar
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7 hours ago, Waldemar said:

As an example of a ship drawing from the 17th century, I still include below a plan of a yacht from 1665, which was built at the Götheborg shipyard by an Englishman, Francis Sheldon.

About that early 17th century English drawing standard, maybe you know how to interpret it.

 

While the plan appears to be a profile with turned bulkheads, the sternpost is somewhat obscured by a part of the hull in pseudo-3d fashion:

 

image.png.f9cbdfa4d8f45413dadd83f92bbb0918.png

Should one assume that to recreate the real profile the sternpost and rudder should be moved slightly back?

 

 

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9 hours ago, Waldemar said:

 

 

True. As an example of a ship drawing from the 17th century, I still include below a plan of a yacht from 1665, which was built at the Götheborg shipyard by an Englishman, Francis Sheldon. This is the oldest extant ship plan in Sweden showing the profile of the frames (stern only). As you can see, the drawing standard is still far from the precise 18th century convention (Swedish archives).

 

I will no longer carry out a reconstruction of this shape, but the frame profiles indicate quite clearly that the designer used the conventional frame-moulding method.

 

image.thumb.jpeg.35c8316d3bab434fa110ba21a0bada09.jpeg

 

 

Just curious if this was an actual build plan or a proposed design and used to get support for the project?

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48 minutes ago, Waldemar said:

No, no, no. I would rather opt for a galley-style stern shape.

It's not just that plan, see for example this:

galley_1625.jpg.b1346b4b775dd1c419a3c76f00d09edd.jpg

 

Or even the stern of the Sovereign of the Seas from Boston Museum:

SC28819.jpg.2fc1cccc09f9e2f35ff8ec98cfb1d618.jpg

 

and my attempt to solve it:

https://modelshipworld.com/topic/23981-early-17-th-century-pseudo-perspective/?do=findComment&comment=708359

https://modelshipworld.com/topic/23981-early-17-th-century-pseudo-perspective/?do=findComment&comment=708755

 

(Sorry for linking posts, it would be a little difficult to recreate the formatting again)

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Mark:

 

The watercolour (plan) is considered a design/proposition for the decoration of the yacht. The design set also includes a simple model made of wood and cardboard, normally unnecessary for an experienced designer himself, so rather intended to be shown to the client. It is kept in the Skokloster castle, Sweden.


Martes:

 

This looks like a bit of a clumsy attempt to gain depth in the image (perspective), and to show elements not normally visible in the profile view. The same could be true of the Swedish yacht, but here we have in addition transom beams with an arched profile. On the other hand, this curved shape could also be a way of showing the shape of these beams as seen from below. There is not yet a consistent application of standard geometric projection methods. Either way, the axial skeleton elements should, in my opinion, definitely remain in place.

 

image.thumb.jpeg.be475558e381100797e1817a6d42289e.jpeg

 

1277194289_Wrangelyacht-model.thumb.jpg.f1bc620bc9e90affb6a6ac5674cf17b2.jpg

 

 

 

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Martes, coincidentally this Swedish yacht designed by an Englishman, can be another excellent example revealing the drawing practices of the era. You can try to compare the shape of the floor/hollowing curves in the stern area as seen on the plan and on the model. Even just by eye. These are for the same ship by the same designer.

 

 

 

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Inserting ready graphics is quick and easy, so one more 'design' draught. This one, from the Swedish archives, is dated circa 1615, and the technical descriptions with dimensions are in English. Here, too, attempts have been made to achieve the effect of perspective. And the jump to geometrically perfect 18th century plans didn't happen overnight.

 

image.thumb.jpeg.9133060d35d961651a7c49f953270207.jpeg

 

 

Edited by Waldemar
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The below description concerning the hollowing/bottom curves was taken from an anonymous (so-called ‘Newton’) manuscript of the English origin of ca. 1600, as published by Richard Barker in The Mariner’s Mirror 1994, Vol. 80, No 1, pp. 16–29. 

 

Except Sutherland’s work, this is perhaps the best (or maybe better: the most detailed) source from this period and from the northern part of the continent on this usually neglected issue. Unfortunately, the pertinent description is not complete either – while the shapes of the hollowing moulds were explained for both the forward and after part of the hull, the author apparently forgot to describe their use.

 

‘20. The length of the sweep of the hollowing moule for aftward must take his proportion from ye length of the sweep of the wrong head & must not be more then 5/6 nor less then 1/3. This arch hath a straight line joyned to it with a true touch wch serveth for the lower part of the moule, & the arch for the higher part. And so the whole moule consisteth of these two parts. The back of the moule & the higher part doth make a true square[;] the making & use whereof shall follow after.

 

21. The hollowing moule for forward must have no right line in it. Therefore there must be a greater arch to this lesser arch of the after hollowing moule, & the length of this greater sweep must take his proportion from the length of the futtick sweep & must not be longer then 3/4 nor less then 1/4 thereof. The use of this hollowing moule shall follow after’.

 

Neither the author of the manuscript bothered to draw the hollowing curves for the main frame on the accompanying sketch, as can be seen in Barker's redrawing of the original.

 

image.thumb.jpeg.92e1c13b3925283984a5b2442852663f.jpeg

 

 

Edited by Waldemar
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It is also worth noting that the author of the manuscript does not talk at all about how to draw these curves on paper, but immediately describes how to prepare templates/moulds for use in the shipyard. Anyway, the whole description seems to be about the non-graphic method of shipbuilding.

 

 

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1 hour ago, druxey said:

Here are photos of a merchantman's hull, as derived by graphic methods, from the Newton manuscript. Comments?

 

 

Yes, here is my comment: two photographs of the model from around 2020 (and still with perspective distortions) are not proof of anything. Rather, I would expect a graphical or at least textual demonstration of the method, as I have done before, also at your request. And an indication of the relevant passage in the 'Newton' manuscript would not be out of place, so that comparison could be made.

 

 

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