|
Post by jules on Aug 18, 2016 11:57:44 GMT
Hi Fred,
Thank you very, very much for this tremendous piece. That last paragraph is a joy; to be part of new insights in the academic side: great stuff. If you let me, I will respond in detail to your piece later on. But, forced by your pace, I first have to write what I was saving up for later. To explain the changes that took place in Dutch shipbuilding between the building of Vasa and the first Anglo Dutch war, roughly between 1628 and 1652, we must take the change in production process into account. We must not forget that what is now commonly described as the static 17th century Dutch shipbuilding, was in its day considered as the most forward and revolutionary shipbuilding of the world. The thing that changed the production process of ships completely, was the introduction of the windpowered sawmill. This was the machine that caused a revolution in Dutch shipbuilding. From the start of its introduction the production time for building ships was reduced formidably, because all the trees were cut to a certain width before they came to the wharves. They may be cut to the width of a deck beam, the width of a hull plank, the width of a wale, and, what's important in this discussion, the width of the frame parts. All the frame parts could be ordered by the shipwright to have a specific width. The guy running the sawmill made sure all the trees were cut to the shipwrights spec, and the cut frameparts came to the wharve. After delivery, all the shipwright had to do, was fit these square and parallel frame parts into his hull shape. To make sure that the shipwright met the strict demands of the contract that the ship should have an ongoing, absolutely closed 'wall of wood' at the bilge and at the ribband (scheerstrook), all he had to do was placing the frame parts against each other. The absolutely square sawn frame parts making sure that everything fitted seamlessly. It was only a matter of placing the frame parts against each other, to assure that he would meet the requirements. And if we know from Witsen and Sturckenburgh that the gunports were formed by the frame parts, and that, by this time, the gun ports were perpendicular to the centerline of the ship, why would the shipwright not make sure that the frames were perpendicular to the centerline of the ship as well? Nothing prevented him from doing so. And if we know from Van Yk that the gunport positions were determined before placing the frames (the gunport positions were marked on the ribband (scheerstrook) before the frames were placed), why wouldn't the shipwright order frame parts with a width that, when placed against each other, would match the distance between the gunports? Again, nothing prevented him from doing so. It all makes a whole lot of sense to me, because it reduces production time enormously. And that is what Dutch shipbuilding was famous for in the 17th century: its enormous speed. And, to get back on topic, as a result of this fast building method, all the frames are parallel to each other, and not tilted.
So I would say there is a break in ship building tradition; it is right there at the time of the invention of the winddriven sawmill. Or, to be more precise, at the point of introduction of premachined wood, cut by the sawmills, on the wharves.
To link this to Vasa, I would like to raise the question if there was precut wood available for the building of Vasa. And if not. Could this explain the kind of haphazard, 'old fashioned' framing of the ship. With all its consequences of skewing and tilting. Or, as others in this forum called it, its wonkiness?
Kind regards,
Jules
|
|
ara
Junior Member
Posts: 69
|
Post by ara on Aug 18, 2016 12:08:35 GMT
Hi Jules,
Do you know the (approximately) exact date of the introduction of the sawmill into shipbuilding, or was it a graduel process? Do we know something about the times of its introduction into the different admiralities? So in Sturckenburghs time it was already in place in Amsterdam? A great sophistication, no doubt. ara
|
|
|
Post by jules on Aug 18, 2016 13:41:02 GMT
Hello Rein,
Here are some data regarding the invention and the introduction of the sawmills. For more information please turn to other sources like Van Dillen. The winddriven sawmill was invented by Cornelis van Uitgeest in 1593. At least, in that year he got his patent for this type of windmil. In 1594 he built his first, small, sawmill. In 1597 he got the patent on the crank shaft he used in his sawmill. The guild of the Amsterdam handsawers resisted against the introduction of these sawmills in Amsterdam, because the sawmills were 30 times faster and delivered better quality; they would be out of a job in no time. So it lasted untill 1631 before the first sawmill was built in Amsterdam. But the sawmills in the Zaanstreek delivered to the shipwharves in Amsterdam way before that.
Returning to your post on the 'all three means of fastening' you found in the Hohenzollern model. Could you please explain what you have found? Maybe you can post a photo with some comments. That would make it easier to answer your question about why the 'little nails' were used in the model. Many thanks in advance.
Kind regards,
Jules
|
|
ara
Junior Member
Posts: 69
|
Post by ara on Aug 18, 2016 14:37:26 GMT
Hi, Jules. Sorry, I´m currently unable to upload pictures. But when I look at a closeup of a hull segment of the HZM (They are to find in the german forum with fine details), I´m not so sure, that I only see treenails and bolts there, especially at plank joints. Aren´t there some nails, too - in that narrow spaces at the end of a plank? In my opinion that´s an indication of frames behind the planks. It´s just an assumption. ara
|
|
|
Post by tromp on Aug 18, 2016 17:42:37 GMT
Hello Fred, Thank you for your contribution, again. And, thank you for the kind words about my contributions. And, if my tone in my post to Peter offended you, I apologize. I would like to say in my defense that this tone was provoked by the snide remarks Peter makes about me in 'his' German forum. And also, a bit, by the not so gentlemanlike remarks Peter makes in this forum. Stuff like: 'Any other approach simply doesn't make sense!', '..., and believe me, they did it that way!', and 'Constructionwise anything else couldn't make sense', I do not consider very gentle. But maybe that's just me, being to sensitive. Indeed! I am not directing every comment I make in the Internet against you! Far from it!
|
|
|
Post by jules on Aug 18, 2016 18:59:49 GMT
Hi Peter (D.G. a.k.a. Tromp), Thank you very much for your reply. This comment on the internet is for you. I promised a while ago that I would come back to the proof for your tilted frame theory related to the Hohenzollern model. Here is part 1 of my promised answer. I first want to express that I think this model is of extreme importance for the understanding of Dutch shipbuilding in the 1660s. It shows tremendous detail, and shows us things that, if we had to rely on other sources only, otherwise would not have been known. But, if we want to know if the model is a good representation of the actual ship, we have to compare it to something else. We could compare it to other contemporary models, descriptions of the ships in contemporary manuscripts and books, or to the contemporary paintings and drawings of the ships. I don't know about you, but what triggered my interest in the beautiful Dutch ships of the 1660s, was their representation on paintings and drawings. And especially their representation on the paintings and drawings of the Van de Veldes. Their works of art shaped the way I look at these ships now. For me a good model is a model that resembles the ships in the Van de Velde works of art. If we wouldn't have their works of art, how would we have known about the difference between, let's say, Zeven Provinciën, Hollandia or Gouden Leeuw? How would we have known about the diferences in building style between the Admiralty of Rotterdam and Amsterdam? Or the diferences between the ships of the 50s and 60s? And so on. The suggestion made in this thread that every artist has altereal motives for making his work of art, can not be applied to these two giants of the marine art. In their time they were famous for their truthful representations of the ships, and, since non of these ships are around anymore, we have to accept their hard earned reputation, and therefore must accept their works of art as truthful representations of their chosen subject: the ship of the second half of the 17th century. If we can accept the Van de Velde art, we are in the good company of Mister Tomesen and his company Artec, who made the ship models for the Reede van Texel diorama; largely based on the representations of the ships by the Van de Veldes. Luckily the Hohenzollern model complies with my selfimposed criterium: the model gives a good representation of what the Van de Veldes show. That is ... for the part above the waterline. The Van de Veldes only show the ships above the waterline. (The only exception I know, is the design drawing for their yacht.) For the comparison of the part of the model under the waterline, we have to turn to other sources. And these sources show something different from what the Hohenzollern model shows. This makes me believe that the Hohenzollern model does not show a 'normal' hull shape of the 1660s. But that's another story... Let's get back to this topic. In your post of the 3rd of July, you included a reproduction of the drawing Mister Wagner made of the side view of the model. In this drawing you added tilted vertical lines as a suggestion for the framing of the model. If I understand correctly, you used the tilting of the gunports as a reference for the tilting of your framing. But, the Wagner plans are a bit conspicuous. They show things that are not in line with what we see on the photographs of the model. For example the shape of the lower transom and the positioning of the gun ports do not comply with the photographic evidence we've got. And, what's worse, Wagners drawings are not in line with the drawings that Mister Winter made when he studied the model, before it was destroyed. One of the things that Winter showed in his 'old' drawings, is that all the gunports are parallel to the vertical station lines. I include two details of his drawings to show this. Winters drawings also show that the vertical station lines are perpendicular to the waterline, not to the keel. He drew the ship (the model) in its sloping position, under 'stuurlast'. So the Winter drawings resemble the Sturckenburgh drawing in this respect. Why Wagner changed all this for the publication of the book in 1967, I do not know. Your guess is as good as mine. So when we constrict ourselves to the plans of the model, I wouldn't know what version to choose; Winters vertical gunports or Wagners tilted gunports. But, pushed to the limit, I would go for the Winter version. This is the man that actually studied the real model; Wagner had to work from sketches, notes and photographs, and made some obvious misstakes. You chose the Wagner version. Would you like to explain why? That's it for now. I'll be back. Kind regards, Jules PS I almost forgot, in my view, the second Sturckenburgh drawing, the vertical section shows, when superimposed over the first drawing, the frame view, that the deck beams were not placed between the frame parts, but butted against them.
|
|
|
Post by tromp on Aug 19, 2016 4:50:25 GMT
You chose the Wagner version. Would you like to explain why? I've been trying to explain this the whole time
Peter
|
|
|
Post by fredhocker on Aug 19, 2016 12:44:12 GMT
The Swedish navy yard was using wind-powered sawmills from about the 1610s, if not earlier. Hybertsson and de Groote's contract for the operation of the navy yard in 1625 included control of a wind-powered mill. Looking at the timbers of the ship, we can see plenty of evidence of its use, but mostly in making boards up to about 6 cm thick. Almost all of the hold bulkheads are planked in spruce converted from the log in a sawmill.
To what degree were frame timbers sawn by machine? I am aware of the extensive use of wind power for converting planking stock, which involves straight logs for the most part, but large crooks and knees and other types of compass timber are very awkward to horse through a stationary saw. What evidence is there for the conversion of framing stock on wind-powered saws in this period? Most of the archaeological evidence I have seen suggests that planking stock could and was converted by sawmills, but surviving sawmarks on frames are more often the type one gets from hand-powered frame saws, and pitsaws/trestlesaws were still a prominent feature of naval shipyards well into the 18th century. The English naval yards, which I have studied for this period, were no strangers to millsawn timber, and used it extensively for planking, but were still relying on large gangs of hand sawyers to convert framing timber. The introduction of sawmills allowed them to reduce the number of sawyers, but not to eliminate them, due to the difficulty of handling frame timber in the saws of the time. On the other hand, many of the framing timbers in Dutch hull forms are straighter and might be more readily converted on a mill.
Another issue to consider here in the gunport-framing argument is the size of the ports. Most sources are pretty clear that gunports should be sized in relation to the guns mounted in them, with a common proportion being 6 round shot high and 5 round shot wide or something similar. A 24-pounder round shot is about 140 mm in diameter, so that makes the appropriate gunport about 70 cm wide, for example. A ship with two gundecks carries lighter guns on the upper gundeck, so the upper ports are narrower. We see this in Vasa (lower ports average about 8 cm wider than the upper), and a number of other ships. Witsen notes (p. 112) in his "certer van een oorlogh schip, genaemnt de Vrede, Anno 1667" that the lower ports are 2½ feet wide, while the upper ports are 2 feet wide. If Jules's logic concerning the relationship between ports and frames is followed, and the shipwright can order the timber appropriately, then he has to use frames of different width or spacing in the area of the upper deck ports than he uses in the area of the lower deck ports, in order to make the frame sides coincide perfectly with the gunport sills. This seems like a lot of complication to me, and we do not see this kind of work in the surviving archaeological examples (which are admittedly few). The archaeological evidence suggests to me that the Dutch achieved speed in construction by using standardized, modular elements over as much of the hull as possible, and then fit the secondary features to this structure, cutting holes where necessary, or adding reinforcing timbers. This is certainly the case with Vasa, and the introduction of sawmills for converting timber would tend to reinforce the standardization aspect more than it would facilitate the custom sizing of frame timber to suit gunport size or spacing. It may be noteworthy in this regard that the certers Witsen quotes often give the sizes of the frame timbers but not the spacing or location of the gunports.
Jules's argument is based largely on logic rather than evidence; it would be logical or easy to do it this way, to make the frame sides coincide with the gunport sides, since it would save the work of notching the frames. That may be true, in terms of the construction of the gunports, but it leads to other complications in larger areas of the structure (such as how to deal with different sized ports, noted above) and there is no evidence that it was done this way. The few archaeological examples of gunports we have (including on English ships, which we know had framing planned to accommodate the ports) indicate that the actual gunport sides often had to be adjusted by notching the frames. Witsen's certers indicate that the important features of the gunports were their size and height from the deck, since those dimensions are specified. They are the functional requirements of a gunport, and so important to specify. The certers for multi-decked ships do not indicate that there were different sized frames to accommodate different sized ports, which one would expect if it was common practice to size the timbers to make them coincide with the ports.
I agree that there is much to be gained in the construction by spacing the frames with some regard to the gunports, since this will make the structure stronger and save some time in construction, but I am not convinced that there was a slavish insistence on an exact correspondence between the frame sides and the ports.
Fred
|
|
|
Post by Peter Jenssen on Aug 19, 2016 13:54:10 GMT
Very interesting discussion continues! Apologies, I have not caught up 100%, I was away. (I have too many things on. Honestly, -a full time job, a family, studies in german and french -with two assignments due in each this week- And trying to get time to build models too.)
I thought in Sweden hydro powered sawmills were more used? Also they would have been around since much earlier than 1600?
So is there something more to the mill technology then than just the possibility of using wind power instead of water? Some method of machine sawing huge curved pieces of oak developed that is not necessarily tied to the power source being wind?
Cheers, Peter (J)
|
|
|
Post by tromp on Aug 19, 2016 14:00:35 GMT
Jules,
there are considerable flaws in the two drawings in your post from yesterday evening. The drawing on the right was drawn neither by Winter nor Wagner, it is known as the Adametz drawing, named after the chap who drew it. No doubt he had his information from Heinrich Winter but if he ever actually saw the real model, we'll never know though it was drawn well before the war. It is not known where he got the measurements from as most of them are incorrect, especially the gunports. The height between the top and bottom sill of the lower ports is given at 5,5cm. If you take the 1:100 scale side-view from the book and measure the space between the second and third wale (counting from the waterline upwards, measured at the waist), multiply this with 100 and divide by 22 you will arrive at 5.2cm, which means the 5,5 for the clearance between the sills is way too much. I have seen smaller scale copies of the HZM in which the modelmaker took these figures for granted and you can easily tell the gunports are way too big. The same applies to the door leading to the quarter Gallery. In both of Winter's longitudinal sections is a step at the foot of this door, which is missing in the Adametz drawing. Thus this door in the Adametzs plan would in real life be a staggering 1,9m high. The plan is beautifully drawn and well detailed but we have to take it with a pinch of salt. At least I do. The drawing on the left was indeed drawn by Heinrich Winter, and if you look closely you'll spot one significant detail: the ports ARE tilted - but not all of them. This is best noticable on the upper gundeck behind the mizzen mast. I hope you don't mind me posting a snippet of this plan here, please just see it under the context that we are discussing the same issue, hoping to come to a conclusion (some day! ;-) ).
bilder kostenlos
The only possibilty I had was to prop up a square against my Monitor and to take a photo of the plan like that. It is odd though that not all ports are tilted, those at the bow clearly aren't. Correspondence between Wagner and Winter survives and I have seen one letter dealing with the Hohenzollernmodel. So I would suggest, that Winter advised Wagner while he was drawing the plans. Wagner's plans are dated 1967 - the year Heinrich Winter died.
Now to answer your question: I am building the model in accordance to what the photographs tell me. Of course I'm using the Wagner plans and others, but if a certain Detail can be made out in the photos which the plans don't show clearly, I'll go for what the photos say. Looking at Rein's comparison on the German Forum between the Gent and the Hohenzollernmodell I'm even more convinced now that the HZM was built with leaning frames and the Gent model wasn't. I have been debating the leaning Frames theory with scholars for more than a year now. Right from the start a lot of respected historians simply refused to accept it (including yourself). Now that it is confirmed that the Vasa was built that way and even more - it was a widespread approach up until second half of the 16th century and looking at pictures of the HZM, I am convinced that it too was built with leaning frames.
Kind regards Peter
|
|
|
Post by jules on Aug 19, 2016 15:26:20 GMT
Hi Fred, Thanks for the reply. My answer is going to be short. Just got home and have to go again. About the gunports. Why is it so hard to accept what Sturckenburgh so clearly shows? Here's another detail of his drawing. Gunports on upper and lower deck between the frame parts. Maybe later fillers were added to reduce the width of the gunports of the upper deck. Please explain what's wrong with this. About the sawmills. There was a differentation between the types of sawmills. There were beamsawers (balkzagers) and planksawers (plankenzagers). The beamsawers had no trouble sawing at the widths of the frames. And had no trouble sawing the 'sommers', the crooked wood. Willem Vos, in his new book, gives great explanations about production methods in the 17th century. I include a photo of a winddriven sawmill sawing planks. Leave out the middle sawblades and it cuts a beam. Even less power needed for that. Regards, Jules
|
|
|
Post by jules on Aug 19, 2016 15:52:50 GMT
Hello Peter (Tromp),
Again, a short answer. We both have the same problem: we can not publish copyright protected material here. Winters publication in Die Yacht is from 1937, and his own drawing is from the Scheepvaartmuseum. They object about publishing, not I. So we both can't publish their stuff, (that's why I had to use the snippets you used in your German forum), and have to describe what we see. I have both drawings opened on my big screen. First to what you say about the, what you guys call, Adametz drawing. This drawing accompanied Winters paper in Die Yacht. I am sure Winter checked this drawing before it was published. His reputation was at stake. There may have been errors in this drawing, but it does serve a purpose in our discussion. The complete drawing shows that the ship is drawn under 'stuurlast', and that the vertical gunport sills are perpendicular to the waterline. OK, the reproduction is a bit wonky, but, in my view, that is what the drawing says. Over to Winters own drawing, the one from the Scheepvaartmuseum, I sent you a while ago. No matter how long I look at it, I even asked my wife Marion to check it, all vertical port sills are parallel to the station lines, which are perpendicular to the waterline, not to the keel. The only thing I could add, is that the waterline in the Museums scan is slightly rotated; it is not exactly horizontal. But the rest of the picture is rotated accordingly, so: stationlines perpendicular to the waterline, vertical gunport sills parallel to the stationlines. The whole picture is slightly rotated. I don't no why your picture shows something else. It might have something to do with taking photographs from screens. I will get back to you on photographic distortions and photographs of ship models later on; I really have to go now.
Kind regards,
Jules
|
|
|
Post by tromp on Aug 20, 2016 8:42:02 GMT
Fred,
thanks for the two plans of Vasa, I never realised that the port sides were splayed that much! Would it be ok for me to post these to the German Forum?
Regards Peter
|
|
|
Post by tromp on Aug 21, 2016 9:08:43 GMT
These are the nails that ara means:
fotos hochlad
There are quite a few of the in the lower two wales. Some can be found beneath the waterline too.
en
|
|
|
Post by jules on Aug 21, 2016 10:07:09 GMT
Hello Peter (Tromp), Here is part 2 of my response to the proof for your tilted frame theory related to the Hohenzollern model. If I'm correct, the main thing that is making you conclude that the frames tilt, is the evidence you found in the photographs taken from the Hohenzollern model. That's what sparked your theory, the rest of the proof was added to support what you saw on this model. That's why you included the Sturckenburgh drawing, the Wagner plan, etc.; they were meant to support what you saw on the model. But, what you can see on an actual model, can look quite different in a photograph of that model. Looking at a model with your own eyes, is something different than looking at it with a camera. Looking at photographs taken with this camera, is yet another experience. In my last post I promised to get back to you on, what I called, photographic distortions and photographs of ship models. Here is part of what I want to say. Underneath I placed a photograph which was taken during the building of the Zeven Provinciën model Otte Blom was building before he died. As you can see in this photograph, all the frames look like they are tilted. We see the effect more near the end of the model, and less at the front of the model. I think this is about the same as what you see in the photographs of the Hohenzollern model. Only we can not see the frames on the photographs of that model, but have to do with gunports and nail patterns that give, let's hope so, an indication of the frames that are hidden underneath the planking. (Please let me know if we don't agree on the assumption that we are looking at the same effect for both models, the Blom model and the Hohenzollern model.) Back to the photograph. The frames look tilted, but the thing is however, that these frames are not tilted at all. They are all placed in a vertical position, and only seem to be tilted. When you look at the white bulkhead/frame holders which are placed vertically at the center line of the model, you can see that these are placed at the positions of the station lines we know from the plans. And like the station lines, they are vertical. Now when we look at the white bulkhead/frames that are attached to these vertical holders, these look tilted. Only, they're not. Since they are attached to the vertical holders, they have to be vertical as well. So the bulkhead/frames only appear to be tilted. To show that mister Blom built his model with vertical frame parts, I included a detail from one of his reconstruction drawings below. Here it is. In this plan we can see that all the frames are vertical, and not tilted. So, things can look different from what they actually are. The model is built with vertical frames, but a photograph of that model shows tilted frames. That's what I called photographic distortion. (I know the term 'photographic distortion' is also used for describing lens deviations, but I couldn't come up with a better word). We technicians are used at looking at plans which show no distortion at all. Every point on a flat surface, the plan, is at the same distance from our eye. When we want to look at a specific point on that surface, we simply move our head. So there is no difference in viewing distance and viewing angle, whatever point on the plan we look at. But when a straight line in a plan is projected on a curved subject like a ships hull, a photograph of that straight line may look curved or tilted. A camera looks at a subject from one point. All the points on a ships hull have a different viewing distance, and a different viewing angle from this one point. So all the points on a ships hull are looked at differently by the camera. This makes straight lines look curved or tilted, quadrants look like rectangles or lozenges, etc. And, this effect varies with the viewing distance, the distance from the camera to the subject. The closer to the subject, the bigger the distortion. To make photographs with lesser distortion, we should move away from the subject, not close up on it. When we move away from the subject, the diferences in viewing distance and viewing angle for the different points on that subject, become relatively smaller: the distortion effect decreases. I hope this helped. More to come. Kind regards, Jules
|
|