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Post by Clayton on Sept 7, 2016 19:09:58 GMT
Hello all!
I have been away awhile; busy with other projects, raising a kid, work and life. But that doesn't mean that I am not interested in this. And I just took some time to read this thread, even though I noticed it awhile ago. This is good discussion, and entertaining at some times too!
I will share some of my experiences framing my model. I tend to like Fred's idea that parallel vs. tilted frames are a product of building method rather than saw technology; tilted in Dutch bottom first method vs. parallel in later construction methods.
I built my model in a way that was similar to how Vasa was originally built. Rather than bottom planking guiding the framing though, I set up bulkheads and strung lath between them to form a basis for where the outside edges of the frames should land. The frames ended up tilted naturally through this method; there was no need to taper width of the frames before I added them. In fact, I used a very precise tool to evenly thickness sand the width of all of the approximately 750 framing members. (The last time I was in Stockholm, I remember talking to Kroum about this number, and he told me this was quite close to the actual number)
My approximate framing plan, which shows the frames tilting at the ends of the ship towards amidships:
This is how the framing started (at around amidships) I purposely deviated a bit from actual construction methods. Instead of a floor timber going across the keel, I purposely made them split between the two sides, so that the two halves of the frame could land in slightly different places, as is reality in the real thing:
And the framing more progressed:
I gently clamped the frames to the lath as I added them so that I knew they would be in the right place while glue set. This picture shows a tilt, considering the bottom edge of the keel as the perpendicular angle to reference it from. I marked out the locations of the top timbers on the lath based on the old plans, but didn't care much if not all of them ended exactly within the marks.
In fact, many of the upper ends of the aft frames seemed to have tilted farther forward than the plans suggested.
The completed framing, with wales added and the gunports cut:
One thing I might add is in addition to studying the angles of model gunports. In models we are talking about very small openings. Making a perfectly square port with edges parallel to anything is difficult, so angled sides, regardless of whether the frames are tilted or not, are going to happen.
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Post by jules on Sept 8, 2016 9:06:24 GMT
Hello all,
A bit disrespectful maybe, but I would like to take the discussion back a step again. I think we're missing a point here. Now that everybody seems to accept Fred's explanation for why frames tilt, it is induced by the bottom based building method, I would like to raise a couple of questions. But first, I admit, a lengthy introduction.
When Fred says on August 30: '... the apparent change from tilted to parallel frames around the middle of the 17th century coincides, more or less, with the abandonment of the bottom-based assembly sequence, I don't think that's a coincidence.', and when I, in reply to this, say: 'I do not see a linked timeframe between the two' ('the two' being the building with tilted frames and the building with the bottom based method), and: 'It looks to me that bottom based shipbuilding outlasted tilted frame shipbuilding.', Fred has to come up with proof that this theory is true; or at least explain why he thinks his theory is true. And when Fred, in his post of September 5 repeats: 'To me, the relative orientation between the frames and bottom planking suggest that tilted frames were a traditional part of the bottom-based method,...', that, for me, does not form a reply to my objections.
Fred's theory that tilted frames are induced by the bottom based building method, maybe true for the time leading up to Vasa, but that does not explain why there was a long period of bottom based shipbuilding with parallel frames after that. We have to look forward from Vasa, not backward: we all seem to agree on seeing a change from tilted to parallel frames after the building of Vasa in 1628 and, say, 1652. When Fred's theory is correct, after this traditional period of about 20 years, there should be no more bottom based shipbuilding. After all, if the only reason for tilting the frames is the bottom based building method, the only explanation for the absence of tilted frames, is the absence of the bottom based building method. So when we see that the bottom based building method still exists after the transitional period, but that tilted frames no longer exist after the transitional period, the theory is not correct. And, in my opinion, that is what we see: the use of tilted frames had stopped in 1660-70, but the bottom based building method is still in use in 1660-70.
And now, finally, to the questions: If Fred's theory about there being a link between the use of tilted framing and bottom based shipbuilding is true, why does the E81 wreck, that sank around 1662, and was built with the bottom first method, show parallel frames? And why doesn't mention Witsen, who spent page after page describing the bottom first building method in 1671 and 1690, mention the tilted frames? These two things show, in my humble opinion, that the tilted frames got abandoned much, much earlier than the bottom first building method. But, if we have elegant answers to these two questions, that leave the theory intact, the theory may be true.
Your thoughts are welcome, as always.
Kind regards,
Jules
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Junior Member
Posts: 69
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Post by ara on Sept 8, 2016 20:18:21 GMT
Hi Jules,
My first thought, when I read this, is, what about the reduced sheer of the decks after the Vasa time? Maybe that´s more likely a reason for no longer tilting the frames like in Vasa. Just a thought. rein
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Post by fredhocker on Sept 9, 2016 13:04:10 GMT
Jules's objections to my interpretation are not at all disrespectful, they are a fundamental part of how scholarship works and I welcome the challenge!
First, let me be clear about what I am saying. What I am pointing out is that tilted frames become less common at about the same time as bottom-based construction begins to fade from the scene, and frame-based building sequences and parallel frames both become more common in the second half of the 17th century than in the first. I believe that this is not simply a coincidence, but that there may be some relationship between the two. Certainly, parallel frames are more or less a necessity in a frame-based approach based on drawing sections of the hull (the most common frame-based approach found in European shipbuilding traditions, not just in the Low Countries and not just in the 17th century). Please note in this statement and in my previous ones that there are a lot of qualifying phrases here, because the transition is gradual and imprecise. I am NOT saying that there is a perfect correspondence between the sequence of construction and the type of framing, only that the chronology and distribution patterns suggest a relationship, one which makes a lot of sense in the larger context of innovation, change and the development of northern European shipbuilding in general. This is where I believe Jules has oversimplified how the process of technical change works, and to a certain degree, how the process of interpreting the archaeological record works.
There was not a single moment in 1659 when some omnipotent power decreed that from January 1, 1660, all ships in the Netherlands would be built in a frame-based manner, or a similar moment when all frames suddenly became parallel. Innovation just does not work that way. Different ideas move in parallel streams in the same time frame, corssing over and influencing each other. New ideas and new methods are adopted gradually and piecemeal, not instantly and universally. Some builders embrace the new idea enthusiastically and completely, while others reject it equally completely, with the majority of builders adapting the new idea to their existing mental and physical toolkit. Thus older methods continue in use, sometimes for quite a long time, even after enough experience has shown most people that the new method is cheaper/more efficient/better. Think of how long it took to persuade people that seatbelts in cars were a good idea, even though statistical evidence was available from the start of the idea that conclusively demonstrated that they dramatically increase your chance of surviving a car crash. Even today, 75 years on, there are still a few die-hards who will only wear one grudgingly.
This is a normal human reaction. Some people are smarter than others, some are more open-minded than others, and a growing economy has plenty of room in it for a wide range of competence. Some boatbuilders are not terribly good at their jobs, but if demand for boats is high, they can still make a living. In the case of shipbuilding and the transition from bottom-based to frame-based, there were certainly builders who continued in the older method well into the later 17th century and beyond. In fact, there are still small-craft builders in some parts of Europe and North America who use this method. For certain hull forms, it is perfectly efficient and does not need to be improved.
There were also builders who could see definite advantages in a frame-based method for the kinds of ships they were building. It gives more freedom in the choice of hull form, for example, and it could, in theory, allow more accurate planning of timber needs. I suspect that the advantages of frame-based construction were most pronounced in larger ships, and would be of special significance for warships, especially given the extreme pressure on warship design and production that engulfed England and the United Provinces in the Anglo-Dutch Wars (1652-1674). For merchant builders, who were building medium-sized and smaller carriers of traditional form, such as E81, it is hardly surprising that they might stick with an old and proven method. Something of the gradualness of this transition is visible in the written works - Witsen, writing around 1670, presents frame-based and bottom-based methods on relatively equal terms, as two alternatives then in use in different regions, while van Yk, a quarter-century later, characterizes the bottom-based method as old-fashioned, obsolete and not worth the time it would take to describe it. They are two different writers, with different backgrounds, different prejudices, and writing at two different points in the transition, but at both points the older method is still in use by some people, probably fewer big ship builders in 1695 than in 1670. The important thing here is that you never convert all the practitioners to the new idea, you mostly outlive them.
We should also remember that frame-based construction did not start suddenly after 1650, Dutch builders had been exposed to it since the late 13th century, when the first Mediteranean merchant galleys began coming to the Low Countries for wool, and increased in the 15th century. By the 1430s, Breton shipwrights, who built in a frame-based manner, were being imported to Holland along with their ships, so some shipwrights in the Low Countries were already experimenting with frame-based approaches two centuries before the period that concerns us. So it should not be a surprise if we encounter early 17th-century Dutch ships which are not bottom-based. This early history is probably a large part of why Witsen eventually characterized the frame-based approach as "southern," since that was the area which had been most intensely exposed to Italian, Iberian and Breton ships and shipbuilders. So by the 17th century, we are actually nearing the end of a long period of what is in fact a double transition, not just bottom-based to frame-based, but also the change from clinker to carvel.
The change from tilted to parallel frames is also a long and gradual one, if one looks at the wider context, a fact which has been obscured somewhat by our focus here on the difference between Vasa and the 1660s. There is plenty of evidence for parallel frames before the 1660s if one looks. Some of the B&W finds at Chrstianshavn in Copenhagen, all dating to before 1650, appear to have parallel frames, although others are tilted. Parallel frames are more or less standard outside of the Netherlands from the early 16th century, and if one goes to the Mediterranean, they are the norm from at least the 9th century, judging by the numerous finds at Yenikapi in Istanbul, and the Bozburun wreck, which I excavated in Turkey. So parallel frames generally predate the introduction of the sawmill by many centuries. In virtually all of the cases outside of the Dutch tradition, parallel frames in the central body of the hull are found in ships with clear evidence of frame-based construction, going back to the 9th century (I can provide a long list of wrecks, if anyone wants). It is hardly surprising that the Northern European ships in this tradition have parallel frames, since the basic design and construction method was originally Mediterranean, introduced to the north in the early 15th century and in some cases specifically taught by immigrants from the south.
The Netherlands is a special case, since the clinker to carvel transition there took a different and more complicated route than elsewhere. Because the Low Countries already had a carvel shipbuilding methodology (the bottoms of medieval cogs were carvel-built), some Dutch builders only adopted the Mediterranean carvel method in part, taking the all-carvel planking and some of the framing arrangement, but leaving the frame-based design method. Thus the bottom-based method which had been used in cogs survived into the 17th century in big ships, with the change that the sides above the turn of the bilge were no longer clinker and plank-first, but carvel and frame-first. Other builders adopted the design and construction methodology more completely, thus leading to two different carvel traditions in the Low Countries, Witsen's northern and southern methods. In the course of the 17th century, the Mediterranean carvel method became more prevalent in Dutch yards, and by the end of the century, van Yk could write about bottom-based construction as obsolete. Why this happened this way is still a matter of debate, but one of the parallel trends that may be related is the growth of modern bureaucratic systems for managing resources and government procurement. The bottom-based method generates no plans, no paper trail and so it is hard to administrate in a bureaucractic system. This was one of the reasons that foreign countries which employed Dutch shipwrights, such as Denmark and Sweden, started to replace their Dutch master builders with British ones from the 1650s.
The relationship between the basic construction concept, bottom or frame, and the way that the frames were set up is not necessarily a direct one. It is not a requirement of the bottom-based method that the frames are tilted or parallel (as the shipwrecks show, with both types of frames found in bottom-based hulls), but the original reason that it was adopted is probably related to the construction sequence. I think it is because it simplified the bevelling of the frame faces (although it does not eliminate it) and results in less extreme bevels generally, which makes the frames stronger for the total volume of wood. As far as I know, the known examples of tilted frames are only found in vessels with clear evidence of bottom-based construction, which suggests a strong connection, and that only bottom-based construction could use tilted frames effectively.
On the other hand, parallel frames are more or less a necessity for a frame-based method of construction in which the frame shapes are determined by whole moulding or a similar process, in which the fundamental concept is that the frames represent parallel cross-sections of the hull. The whole-moulding method and its derivatives, in which frame shapes are derived by incremental adjustment of a master frame shape, was the most common frame-based method in use until the end of the 18th century, and it is based on the assumption that the frames are parallel. As far as I know, all of the known examples of ships with clear evidence of frame-based design/construction have parallel frames.
Please note that this describes two clear alternatives and two sets of evidence in the archaeological record, but does not necessarily cover all the possibilities: 1. Known tilted frames occur in ships with clear evidence of bottom-based construction. 2. Known frame-based ships have parallel frames.
Note that these two propositions work in opposite directions: tilted frames require a bottom-based sequence, but a frame-based sequence requires parallel frames. None of this precludes building a bottom-based ship with parallel frames (since parallel frames can be used in either sequence), it only requires a slight change in the process of bevelling the frame faces in the bottom. On the other hand, it is practically impossible to build a frame-based ship with tilted frames - the known design methods simply will not work. Even if tilted frames started with bottom-based ships (we see them in Roman barges and cogs), they were not essential to the method, and so could be abandoned without having to abandon the method in its entirety. Bottom-based construction began in ships in which the bottom was structurally distinct from the sides (a flat platform in barges, or the carvel bottom of a cog), but by the 17th century, all that was left of this original concept was a construction sequence, and there was no longer any clear structural distinction between the bottom and sides.
Going back to the nature of technological change, it is entirely typical of how innovation is adopted. In this case, I have no trouble believing that some bottom-based builders, especially those working on ships with flat floors and short entrance and run (so long flat buttock lines over most of the length), could use parallel frames. In such ships,even if the frames were set perpendicular to the bottom planks, there would be a lot less tilt than in Vasa. So E81,even if it is both bottom-based and has parallel frames, does not disprove anything.
Now, what about E81? We have been using this vessel as an example of a ship built in the bottom-based tradition (which was a little old-fashioned at the time it was built, but not unreasonable), but with parallel frames, but in fact no hard evidence for either of these presumptions has been presented. I have conceded for the moment Jules's observations concerning that hull, but now that this vessel seems to be central to the argument, we need to look more closely. Here is what we need:
1. Proof that the hull is bottom-based. Among those of us who have been looking at these vessels for the last thirty years, the most readily discernable evidence for this construction sequence is spijkerpennen (the little nail plugs left behind from the temporary cleats holding the bottom planks together) on both the inside and the outside of the hull, specifically under the frames, to show that the bottom planks were erected and held together before the floor timbers were inserted. Since E81 was cut into sections, but not completely dismantled, we do not really have access to the surfaces that we need to see. Spijkerpennen on the outside do not prove anything, since there is evidence that frame-based ships were sometimes built with the assistance of cleats or staging applied across the seams on the outside as a method of clamping planks in place on the pre-erected frames. In the beurtschip OB71 (built 1587), for example, the spijkerpennen were most densely packed on the bottom of the hull, but there are some on the outer surfaces of the upper strakes, which had been applied to standing frames. I helped Rob Oosting with some of the recording of E81 in 1986, before it was moved from Ketelhaven, and we found lots of spijkerpennen on the outside of the bottom, in a similar distribution to what I saw in recording OB71. We could not see very much of the interior surface of the planking, but we did find enough spijkerpennen on the inside at cuts in the timbers to be confident that the ship was bottom-based. So no argument there.
2. Proof that the frames were parallel over the length of the hull. THe best evidence here would be a detailed and accurate framing plan of E81 that would allow us to assess the frame angles with confidence. Jules was unwilling to take my word for it that Vasa's frames were tilted until "we see Kroum's report," or at least the raw data, so I produced the data to confirm my observation. I think it is only fair that we apply the same test to E81. So far, the only evidence produced is photographs of small sections of the hull during excavation (and we have already been down the tortuous road of interpreting angles on curved surfaces in photos, so no help there), and a model made by the modelmaker at the old Museum voor Scheepsarcheologie (at least, the photos look like the model, which I knew from the time when I worked there). It has been claimed that we can rely on this, because everyone knows how accurate those models are. Well, not so fast. A model is an interpretation, not the real thing. I was involved in two model projects in that series (not E81), and I can report that the modelmaker applied a fair bit of his own interpretation in the models, in some cases diverging from the archaeological evidence because it did not look "Dutch" enough for his taste. So I would be hesitant to accept his model from that period as definitive evidence of something as subtle as we are discussing. I would like to see some detailed measurements of the framing and a similar drawing to the one of Vasa's framing that I posted here. Because of the more boxy hull shape of E81 (it effectively has a long dead flat over much of the middle of the length), there is less sweep in the bottom fore-and aft, so even if the frames were set perpendicular to the planking, they might be very close to parallel. As Peter and I have already demonstrated, even with the "extreme" tilt in Vasa's frames, the actual amount of taper in any one frame is relatively little, a matter of millimeters. We are also missing most of the framing from E81 in the area that would be most interesting, since the areas of preserved framing are concentrated at amidships (where they would appear to be parallel in either case) and at the ends, which present special problems in the framing process. When the hull was salvaged, it was cut into five parts. The bow, stern and a short section amidships were kept at their full height (up to about the waterline), but the two long sections in between these were cut down to short backbones, with the floor timbers sawn off near the keel. So we cannot really see if the frames in this area tilt or not, at least not directly. One would need to look at the documentation made before the ship was dismembered, if it shows the framing accurately. Still, as I pointed out above, whether or not E81 has parallel frames is not essential to my argument, given the nature of the transition.
Ultimately, we are limited in how far we can go in this discussion by the nature of the evidence. We are forcing a couple of written sources,some drawings, a couple of models, and a handful of shipwrecks to carry an aweful lot of weight. The wrecks are few and far between, of a wide variety of hull shapes and sizes, and unevenly distributed both geographically and chronologically, so they cannot be considered a true representative sample. The written sources are also a minefield. Witsen was not a shipwright, but an enthusiastic collector of information. The information he collected covers a wide range of time and place, and he does not collate it very well, so it is hard to be certain when he talks about a specific feature if it is something typical of his time or something he found in one of the older contracts, or learned from talking to a retired shipwright trained in the 1610s. Just as we should be careful of worshipping too often at the alter of Vasa, we should be a little wary of the gospel according to Witsen. Just because he does not mention something, it does not mean that it did not happen, only that he did not know about it or consider it important. The certers that he reproduces, assuming that he did not edit them, are in some ways more useful, as they reflect real practice rather than his interpretation of it.
For me, the bottom line is not about details, or specific technical changes, but the broader context of how shipbuilders adapted, or di not, to changing circumstances. I am not convinced by technologically deterministic arguments, since it is rarely the case that a single technical developmnet causes wholesale change on its own. The real world is a messy, complicated place, to which people like Witsen and van Yk tried to bring some sense of order, just as we do today, but the wide variation in individual human beings means that there is always a healthy dose of inconsistency, obstinacy and downright stupidity in the actual decisions made by real people, alongside inspiration, brilliance, and improvisation, all in an environment often driven by the economic imperative to get stuff done.
So in sum, I stand by what I said. I think that there is a connection between construction sequence and frame orientation, but it is not a simple or deterministic one. I also think it is a valuable result of this discussion that we have been able to examine the topic in such detail. And it all started with an attempt to make a copy of a model, not even a model of a ship! So thanks to Peter, Peter, Jules and everyone else who has participated!
Fred
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Post by jules on Sept 11, 2016 18:56:21 GMT
Hi all, I prepared a very long piece to post here, but decided against it. This is the short version. E81, unlike Vasa, shows its frames. The drying of the planking created openings between the planking. So I could see the framing, and I saw it was parallel. And I saw my observation confirmed by the model. So, parallel frames in combination with the bottom based building method. Witsen, describing the bottom based building method in extenso, doesn't mention tilted frames, and shows proof for parallel frames in combination with this building method. I do not understand how anyone can say anything sensible about this building method, if he doesn't accept the only source that thoroughly describes it. I would like to end my short version with this: The people in the know will recognize this immediately. For the people who are not, it's from Witsen's book and it shows parallel framing in a ship that was built bottom based. It's a complete mystery to me why during this whole discussion nobody came up with this. But I can already hear that whisper again: 'yeah, ok, but what did Witsen know? He was just a burgomaster... Good bye, Jules
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Post by amateur on Sept 11, 2016 19:51:48 GMT
Hi Jules,
Two questions on Witsen, both perhaps a bit naive.... The picture shows the liggers to be at 90 degree angle. The discussion was also/mainly on tilted oplangen, but there are no oplangen visible in this picture. How can this drawing be proof of parallel frames? Second, even more naive, Witsen does not describe tilted frames, but as far a I could find, he does not describe parrallel frames either. So,even if we take him as an important source, how can we be sure that he uses parallel framing? (Or did I miss the exact textfragment?)
Jan
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Post by Peter Jenssen on Sept 11, 2016 22:38:26 GMT
Thank you Fred,
A very interesting read indeed!
Basically, things vary. Categorical answers are difficult.
Still unclear to me what it was that was invented with respect to sawmill technology. Not the sawmill itself, even the Romans had that. In Sweden, Forsvik mill is mentioned in 1410, when Cecilia Jonsdotter donates Forsvik to the Vadstena convent. (I found they used it to saw building timber for the new convent buildings, as well as run a hammer forge. Same sawmill Gustav Vasa sourced the timber for his castle in Vadstena in the early 1500s) Wind power? As mentioned earlier, that was at least around in 1610. Multiple parallell blades?
Looking up Wikipedia could have anyone believe Forsvik started 1686 by Anton Boij. Yet it's fairly easy to find a picture of the original 1410 document transferring ownership from Cecilia to the church online. On the Forsvik home page. For me, in the past I found several times that I got caught out by not looking any further when I found what I looked for. When I wondered about the assertion that Vasa was an experiment in building a much larger than usual warship for example, I looked and found that she was one of two ordered to the same size and the second one did not sink. There were even further examples, such as the "Äpplet" from Västervik. I stopped looking, -missing, for example, that there may have been at least one larger ship at the docks near where Vasa was being built, just possibly in the process of being broken up at this time? (I'm talking about The Julius Caesar of around 1590 -launch year seems a bit vague- which appears to list anchor cable specifications at four times the strength of those given to the Vasa, which I find quite amazing.) It's pretty clear that as you collect more information, you are still in the same situation (albeit to a lesser extent). There are still facts you cannot know because the records are lost, there will still be information that is wrong, even in original sources (Wikipedia didn't invent getting things wrong after all). You have just moved your positions a bit. As usual, what's true changes along with the pool of knowledge.
Further to the logistics of shipbuilding, it appears to have been a quite distributed production in Sweden in the late 1500s. Water powered mills would already exist in several places around the country. I would have thought them a quite important prerequisite for a successful timber export industry for example?
Since oak trees all over the country was for the kings use only, to build ships, you have to have the means to use them for that. It would make sense to build the ships where the great oaks were. If so, you would need to establish a lot of shipyards as you go through the oak supply. Is it possible that perhaps the introduction of Dutch shipwrights were in order to boost the number of shipwrights rather than to introduce new technologies? Were there even fundamental differences compared to domestic methods?
The narrative from my visit to the Vasa museum as a child does seem wrong on so many accounts; That Gustav II Adolf brought foreign shipwrights with modern technology to Sweden to build one ship that was to be bigger than anything previously seen, and then arrogantly imposed his own design changes on a half built ship to make it even bigger, causing it to become top-heavy, -laws of physics punishing him for his folly. A prime example of management fail pushing the boundaries without trusting the experts.
Rather, it seems like in Stockholm Shipyard, they hadn't been building large ships for decades, Other places around the country, they had. Ship building was in expansion. Needed in wars against Denmark, Poland, Lybeck etc. Dutch shipwrights were increasingly used because they were running out of the Swedish trained, and the Vasa was not even the only failure. Just a very spectacular one that didn't get broken up, sold off or rotted at the dock, instead sinking with loss of timber, people and valuable bronze cannon... The Vasa was not special, but it was not the same as any other ship either, because they were all built somewhat differently.
I certainly have learnt a lot of interesting things throughout this discussion. A discussion on framing methods of Dutch ships specifically in 1660 and what can be categorically stated about this, on a Vasa forum!
Thank you all!
Cheers, Peter (J)
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Post by fredhocker on Sept 12, 2016 10:23:32 GMT
Hi Peter,
I think there is evidence for sawmills in operation already in the 14th century in Poland, but I would need to track down the reference. So you are right, sawmills are not a new technology in the 17th century.
As for distributed production of ships for the Swedish navy, the records indicate that ships were built near the source of the timber from Gustav Vasa's time until the 1610s, so that ships were built all over Sweden and Finland, with a couple of the largest ships, such as Mars, built on Lake Mälaren. Very few ships were built in Stockholm in these years, it served as a fleet maintenance facility. Around 1618 Gustav Adolf and Axel Oxenstierna consolidated new construction into just a few places, primarily the Stockholm navy yard but also a yard in Västervik and one in Göteborg. The emphasis seems to have resulted from a realization that while building the ships where the timber stood might be cheaper per ship, it limited the scale of production, since the critical resource was not timber but trained shipwrights. I think it is much as you say, that the expansion of military power, coupled with the creation of a long-term shipbuilding program at het beginning of the 1620s resulted not only in the consolidation of the shipyards but also in the recruiting large numebrs of Dutch carpenters. Master shipwrights and other leading technicians had been recruited from Holland from the beginning of the 17th century, but the 1620s saw large-scale recruitment of seasonal workers abroad.
You are also right that we have changed the story we tell at the museum pretty drastically in the last 15 years, thanks to a large amount of new research. We do not take anything for granted, but go back to the primary sources, both historical and archaeological, and look at them critically.
Fred
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Post by fredhocker on Sept 12, 2016 11:51:46 GMT
Concerning Witsen, it is not a matter of accepting it or not, it is a matter of figuring out how to interpret it, the same as any other piece of evidence. Witsen did not make it any easier for us, since he combined so many things and had a confusing method of organizing them. He is invaluable because he was a broad collector of information. In this regard, we are lucky that he was not a trained shipwright, because he wrote down stuff that a shipwright probably would not have, details a practitioner would take for granted (this is the problem we have in interpreting the surviving sources from 15th-century Italy, they were written by practitioners for practitioners, and leave too much out). Witsen thus provides us with a wealth of detail that we would not otherwise have, and he does so without the prejudices that van Yk brings. On the other hand, like every author in history, he has made conscious choices about what to include and what to leave out, about what is important or not, and everything he reports is filtered through his own understanding. There may be details that he did not understand, or features he left out because he did not think them important enough to include, but a shipwright might think differently. A shipwright presenting the same material would also make choices about what to include and what to leave out, and they would be different choices. Our task as historians is to figure out what was really going on, and to do that we have to make some judgments about which filters were being used by each author. Witsen is a challenge precisely because he is so comprehensive, down to different variations of which tools were used in different yards, so he gives us a lot of good material, but he does not always provide a clear context.
Just because one source is comprehensive and provides a wealth of detail does not mean that it is the Truth ordained by God, or that it covers the subject as completely as we would like. Witsen covers large ships pretty well, but small craft get progressively less detail, for example. We cannot ignore other types of evidence in favor of one, we have to balance all of the source material, historical, artistic and archaeological, if we want an accurate picture of what was going on. We should also remember in the case of every single piece of evidence that just because it has a lot of desirable detail does not mean it is right, and that absence of evidence is not evidence of absence. Just because Witsen does not mention it does not mean it was not there. It would be so much easier if he had written , in 1671, that in his grandfather's time the frames were tilted, but nobody does that any more because of [fill in the blank]. Unfortunately, he does not provide any direct indication of whether he was even aware of this older practice.
In the case of our original question, tilted or parallel frames, this is an issue that Witsen does not discuss, either because he was not aware of it or because he did not think it was important. As we have already determined by other evidence, by the time Witsen was writing, parallel frames were the norm, so it is not surprising that he does not take it up. It is also not surprising that in those drawings in which he shows frames, they are parallel, within the limits of the drawing and engraving techniques used to print books. One must remember here that while Witsen himself made some of the drawings for the book, they then went to an engraver to be turned into printing plates, and mistakes creep in at that stage. By comparison, his Swedish contemporary and acquaintance Rålamb (1691) complains all the time about how the engraver got things wrong in his illustrations.
In the case of the illustration reproduced above (Plate XLII, no. 21, with accompanying text on pp. 58-59) we should consider the context and the purpose of this illustration before deciding which parts of it to trust or not. In this case, the text makes clear that the purpose of this illustration is to show the internal divisions of the hull and the timbers which support the decks, masts, etc. Almost all of the timbers in the image have letters beside them, keyed to descriptions in the text. It is a sort of general arrangement drawing, to inform the reader what the names of the different timbers and spaces are and where they are found in the ship, and is necessarily schematic. It is not meant to show the construction process, or to convey accurately the shape of the ship or any of its components, since that is not what is being discussed in this part of the book. The shape and proportions of the hull shown here do not really agree very well with the dimensions and other drawings of the pinas which serves as the example vessel for Witsen's presentation of how one builds a ship. The decks, for example, are shown as lines, without thickness, and they are not smooth sweeps, but straight segments. Many other details are quite crude or simplified. The keelson is straight over most of the length, with the floor timbers moulded more or less the same throughout, even though other information about this particular vessel (in the section on how to build the ship starting on page 144 and plate XLVII) suggests that the rise in the run is more gradual, leading to increasingly deep floor timbers at the keel towards the stern. If one looks closely at the cross sections of the frames, some of the lines which represent the fore and after sides of the floor timbers are perpendicular to the keel, but others, particularly towards the stern, are not. Some lean forward, some lean aft. This seems to be more a result of the (lack of) care taken by the man who engraved the plates than an attempt to show accurately the exact shape and orientation of each frame. Witsen was capable of good draftsmanship (just look at Plate XLIV two pages later), but here, the function of the image did not require such refinement. So is this evidence of parallel frames? Based on the image itself and its schematic nature, it is hard to say that we can rely on that level of detail, but the context around it gives us no reason to doubt it. There is also no internal evidence in this image, or the accompanying text, that tells us whether the ship was built bottom-based or not, although we can probably infer that it is bottom-based from the overall context of the series of images in this part of the book, and their relationship to the later on how to put the parts together.
What we could say about Witsen's take on the tilted/parallel issue is that even though he does not explicitly discuss it, it seems to be that he assumes that frames are parallel, since that is how he always draws them, whether in a very schematic fashion as in plate XLII, or in fine detail, as in plate LXVIII (at page 173), when making orthographic projections. His perspective views are less helpful, since he was not very good at perspective drawing. The frames in plate LIV, which is almost an orthographic projection, seem to lean away from the centerline towards the ends, a tendency that starts close to amidships, but does Witsen mean to indicate that this is how the frames are oriented, or is it a failed attempt to imbue the drawing with perspective? In plates LV and LVI, the frames at the stern lean aft, while those at the bow also lean aft, in these cases it seems clearer that he was attempting to give the drawing perspective.
In short, one cannot take Witsen, or any other source, at face value, it has to be subjected to some critical evaluation and combined with the other source material in order to get a useful impression of what was really happening in the shipyards. As Ab Hoving and his colleageus have demonstrated, it is possible to build a ship according to the information that Witsen presents, which gives us some confidence in what he says, but one still has to make some informed choices along the way, and one has to rely on other sources for the details Witsen left out.
Sorry if I am getting pedantic here, but this is the subject on which I wrote my dissertation, and I have taught the research methodology for recording and interpreting shipwrecks for 30 years, so it is a little too easy for me to slip back into professor mode.
One thing I would like to mention is that in the third Vasa volume, on the construction of the hull, I will be referring to these discussions fairly often, since we have come upon some interesting things that have not been discussed among academics in much detail. I would like to give credit to you all for being part of the discussion, but need to know how you would like to be credited. If you are wary of revealing your true names, it is fine to be cited by your "avatar." If you prefer to be cited by name, email me (fred.hocker@maritima.se) to let me know what it is.
Fred
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Post by Peter Jenssen on Sept 13, 2016 8:03:07 GMT
You are also right that we have changed the story we tell at the museum pretty drastically in the last 15 years, thanks to a large amount of new research. We do not take anything for granted, but go back to the primary sources, both historical and archaeological, and look at them critically. Thanks Fred, It was 1979 when I visited the museum as a child, the museum was a corrugated steel shed on a barge, constant spraying going on inside. The illustrations were of course invariably showing the blue and gold colour scheme. I visited again in 2005, with my wife and kids, but not very long visit (as long the kids attention span lasted :-) ) It's interesting to glean some insight into what was happening around the shipyards, to get some context into the ship building. Logistics, demands competition etc. I found several interesting leads on the internet and it's interesting to see that there is still a lot to learn. Cheers, Peter
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Post by jules on Sept 13, 2016 13:06:43 GMT
Hello Jan,
I already said good bye to this discussion, but it seems that circumstances make me join again.
The discussion has changed a bit. August 30 Fred linked bottom based building to the tilting of the frames. When you do that, the bottom timbers need to tilt according to the sheer of the bottom. In Witsen's drawing they do not. They stay parallel, even when going forward, past the keel, over the stern post. As mentioned before, in a reply to Rein, this parallel position over the stern post is confirmed by the E81-wreck, and the Sturckenburgh-drawing. According to Fred and Peter Jenssen, the continuation of parallel framing in the front and aft of the ship would result in a lot of extra work for the ship builders. But apparently the ship builders didn't mind.
It is not for me to prove why Witsen doesn't mention the frames to be parallel, it is for people who say the frames are tilted, to prove that Witsen was wrong in showing parallel frames in this drawing. After all, should I prove that the frames are not horizontal, diagonal or circular? Witsen doesn't exclude these things either, so I would have to prove why? I don't think so, and I won't.
Kind regards,
Jules
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Post by Peter Jenssen on Sept 14, 2016 3:53:00 GMT
Hello Jan, I already said good bye to this discussion, but it seems that circumstances make me join again. The discussion has changed a bit. August 30 Fred linked bottom based building to the tilting of the frames. When you do that, the bottom timbers need to tilt according to the sheer of the bottom. In Witsen's drawing they do not. They stay parallel, even when going forward, past the keel, over the stern post. As mentioned before, in a reply to Rein, this parallel position over the stern post is confirmed by the E81-wreck, and the Sturckenburgh-drawing. According to Fred and Peter Jenssen, the continuation of parallel framing in the front and aft of the ship would result in a lot of extra work for the ship builders. But apparently the ship builders didn't mind. It is not for me to prove why Witsen doesn't mention the frames to be parallel, it is for people who say the frames are tilted, to prove that Witsen was wrong in showing parallel frames in this drawing. After all, should I prove that the frames are not horizontal, diagonal or circular? Witsen doesn't exclude these things either, so I would have to prove why? I don't think so, and I won't. Kind regards, Jules Hi Jules, My understanding of the discussion is slightly different. Yes, when you tilt the frames, the tilt is caused by placing square timbers along the sheer of the bottom planking. My point was that the extra work would not be required to tilt the frames, but rather to make them stand straight. As Fred pointed out, there are advantages that are becoming increasingly attractive in making the frames parallel. (Better paper trail, easier to work off plans etc) The extra work is not without gain. It seems reasonable to think they would not mind. That there is a link between the abandonment of bottom based building and the introduction of parallel frames, does not necessarily mean that both happens at the exact time. One can cause the other gradually across a time span. Tilted frames requires bottom first, frame based requires parallel frames, but parallel frames can be used in bottom first build (according to Fred's post 9/9, Paragraph 11) (I would think that, in this historical evolution, once you are using full frames, having a prepared bottom to install them into becomes unnecessary and it would be easier then to fair the frames from the outside and then plank.) I certainly don't believe Witsen was wrong in what he is showing, but it seems to me that he is showing a moment in time during a method transition. So, when he draws the frames parallel, does that mean that it's the only way he saw it done? That it was the only way that it WAS done? That it's seen as the modern method, so that's what he chose to draw? -Difficult to know, if he didn't seem to think it worth mentioning. Cheers, Peter
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Post by fredhocker on Sept 14, 2016 8:48:22 GMT
I believe Jules has misunderstood my post. In essence, I agree with him that what Witsen shows is parallel frames, and he does so consistently. As far as we can tell, he seems to regard this as the normal way to frame a ship or boat. But because he does not say anything about it, we cannot say from his book alone why he thought this. It may be because that is how things really were and he had observed it carefully, or because it was not an issue he considered important and he was focusing on other things, or maybe he just did not know and made an assumption. He is very detailed about some things which he thought were important, so not saying anything about how the frames were oriented leaves us wondering why. It is not a matter of prooving one thing or another. Fortunately, there is plenty of other evidence from the second half of the 17th century that corroborates what he shows, and we can add Witsen to the pile of evidence that indicates that parallel frames were the norm in his period. I thought that we had more or less settled this issue. But just to be sure, I will repeat in the simplest terms possible, for clarity:
I believe that by the second half of the 17th century, parallel frames were the most common type of framing in Dutch shipyards, and that all of the different types of evidence available to us are more or less in agreement about this. This is true for ships built in both the bottom-based and frame-based traditions.
But surely even Jules will accept that some Dutch ships in earlier periods were built with tilted frames (or are we still in doubt about this?), so a reasonable question to ask is why, and why did it not persist? My research interests tend to focus on why people decide to change how they do things, so this is the part of the problem that most fascinates me. We have looked at several different possibilities, including changes in how timber was converted (sawing v. hewing), construction sequence (bottom-based v frame-based) and labor saving (reducing the amount of wood to be trimmed in fitting the frames to the hull shape). There may be some truth in all of them.
Jules's argument, as I understand it,is that the existance of bottom-based ships with parallel frames, such as Witsen's pinas or E81 (I will leave aside the question of what the actual framing method of that ship is, and for the moment I will accept Jules's word that the frames are parallel, even if he would not do me the same courtesy concerning Vasa's tilted frames) proves that framing system is not related to construction sequence, but this is not the case. What Witsen and E81 show is that by the 1660s or so, even bottom-based ships were built with parallel frames. They do nothing to explain how ships were built a generation earlier, or why tilted frames were ever used. In that sense, they are of limited help in answering the question.
Individual aspects of construction do not exist indepedently, they must go together to make a whole, so shipbuilding traditions consist of an interrelated set of features, not separate components that one can mix and match according to whim. Changing one thing changes other things.
What I suggest is that tilted frames were originally part of the bottom-based tradition (plenty of evidence linking the two before about 1650), and it was possible to use them in this tradition because the frames were added to the bottom, and so did not need to be parallel in order to be useful shaping or design elements. It may have been preferred over other alternatives because it meant less beveling of the frame and ceiling faces over much of the length (you cannot get away from it at the ends), but we do not have anyone to ask about this, so it will probably have to remain speculation. In any case, the archaeological evidence for this type of framing is confined to bottom-based ships. You cannot, practically, build a frame-based ship with tilted frames, but you can build a bottom-based one that way.
By the later 17th century, even bottom-based ships used parallel frames, because you CAN build a bottom-based ship that way, even if you cannot build a frame-based ship with tilted frames. So sometime in the course of the 17th century, shipwrights working in the bottom-based tradition abandoned tilted frames in favor of parallel frames. This does not mean that tilted frames were not originally related to the construction sequence, only that shipwrights changed the way they worked, probably because they saw some advantage in it (most people do not willingly change their habits in order to realize a disadvantage). At the same time as this change was happening, shipwrights were abandoning the bottom-based method in favor of frame-based construction more generally, at least for big vessels. Witsen and E81 are part of the evidence for this transition.
The question remains, why did people use tilted frames in the first place and why did they abandon the technique? Jules's sawmill theory is a possible explanation of the change, but not of the original practice, aside from the chronological and evidential problems (parallel frames predate sawmills by centuries, for example, and sawmills similarly predate the transition by centuries). I think that the change was driven by, although not limited to, the role that frames played in shaping the hull. One thing which would be interesting to investigate is whether bottom-based ships like E81 used some frames set up early to control the shape. We may have evidence of this on Vasa, so it is not unreasonable, and this would help to explain why bottom-based builders adopted parallel frames as well.
Fred
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Post by amateur on Sept 14, 2016 11:59:16 GMT
Just a question: the shipwreck so1 from the scheurrak has been quite well documented. Inthis cas the whole ship-side has been preserved. Is there any evidence of tilted frames here? (Yes I know, it is quite well before Vasa, so it cant contribute to the discussion on the 1670's style)
Jan
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Post by jules on Sept 14, 2016 15:59:04 GMT
Hello Peter J, To say it bluntly, I don't care about placing it in a time frame or whatever. All I care about is how it was done in the 1660s-70s at the Admiral's wharf in Amsterdam. To be even more precise, I only care about how it was done for one ship. What Fred is doing for Vasa, I'm doing for another ship. Fred is building a comprehensible data set for Vasa, I'm building a comprehensible data set for this ship. (Drawing Van de Velde the elder, National Maritime Museum, Greenwich) It is the Gouden Leeuw, built in 1666-67 by the Admiralty of Amsterdam. I am writing a book about the history of this ship, and a large part of its history is, of course, me being a technical guy, its concept and its building. I know this ship was built using the bottom based building method. And the question for me is simple: do I need to give 'my ship' tilted frames or not? Nothing in all the evidence I had gathered over the last 30 years or so, showed tilted frames (Witsen only providing part of the evidence. There is a lot more). And then someone comes along making statements about how 'my ship' was built, with tilted frames, and I saw this confirmed by an archaeologist I respect greatly. It's time to get active, I thought, we can't have that! So let me tell you how I think this discussion progressed (at the risk of being pedantic): June 25, Peter (Tromp) posted his theory about the tilted frames in Dutch ships. July 4, the discussion ended with the consensus that the frames of Dutch built ships tilt during the 17th century. The thread died, 200 views, that's it. July 28, I thought this had gone too far, and started chipping away the evidence for the theory. Starting with archaeology: E81 shows parallel frames in combination with the bottom based building method. August 14, Peter (Tromp) stated that frames had to tilt because the deck beams have to fit between the frames. This evidence was chipped away by Fred and me. August 15, I tried to introduce a time slot to the discussion: 1660s-70s, and asked if we can accept that gunports are formed by the frames. August 16, I said that Sturckenburgh shows parallel frames; chipping away more evidence. August 18, I posted about the sawmill technology in Holland. Linking building method to the preproduction of parts. And I posted the first bit for chipping away the Hohenzollern model proof (1660-70) for tilted frames. August 21, I posted the second bit for chipping away the Hoh.model evidence. August 23, I posted the third bit for chipping away the Hoh.model evidence. August 26, Gent materialized. August 29, I gave a sum up of all the evidence for the tilted frame theory that had been chipped away, and chipped away some more. And asked: why would they make tilted frames in the first place? August 30, your argument for the tilted frames was that the floor timbers follow the sheer of the bottom. Fred linked tilting to the bottom based building method. He called it 'one issue that has not been discussed yet'. Everybody agreed with his theory until September 8. August 31, Peter (Tromp) posted new evidence for the tilting, placing straight frames against planking is easier, and less work. (This evidence was chipped away by you and me (Sept.5). I replied to Fred that I doubted there was a link between bottom based ship building and tilted frames. September 1, Rein asked me if E81 shows tilted frames on the sternpost. Very relevant question, but looks like it wasn't noticed. If the shipwrights didn't mind doing the extra work on working the frames here, why would they mind doing it for the rest of the bottom? September 4, I answered Rein: in E81 frames are parallel on the stern post. September 5, I chipped away the evidence Peter (Tromp) came up with on Aug.31. And chipped away the evidence Jan (Amateur) came up with from Van Yk. September 8, because everybody seemed to agree with Fred's link of the bottom based building method with tilted frames, I had to make clear that 'we're missing a point here'. Fred hadn't answered my objections to his theory yet. (This changed Fred's tone a bit) September 11, I posted the Witsen drawing, that no one, inexplicably, during this whole discussion produced. September 14, it looks, I am careful, that there are no more arguments for why the tilting of the frames was necessary. And we all seem to agree that parallel framing was 'normal' and that it was combined with the bottom based building method. I can sleep in peace again: I do not need to scrap my research, or rewrite my book, everything is good again. (And, oh yeah, I almost forgot, somewhere along the line it was also made very clear that Vasa does not show 1660-70 shipbuilding.) (And, to answer Fred's question, do I want to be mentioned by my full name when he uses the research I have presented here? Hell, yeah. And don't he forget it. ) What worried me most in your answers, is that you make it sound as if it is very easy to place the floor timbers when following the sheer of the bottom. Keep in mind, it is a lot of work to shape the floor timbers according to the bottom. The bottom, at its extremities, is not a flat thing at all. It has a v-shape with a lot of curvature. Not easy to fit your floor timbers to that, parallel or tilted. I think the shipbuilders had a choice in making the floortimbers parallel or tilted, they sure were able to build both, they just preferred to do it parallel. And maybe this was induced by the demands in the contracts: the frames had to be placed against eachother in the bilges and at the lower wales. And again, it seems I can not stress this enough, when I say these things in this forum, I restrict myself to the 1660s and 70s. In my book I will explain why I dare to stretch this timeline. (And, I will surely go further into the advantages of the sawmills. You, and Fred, made clear to me that people do not take at face value what we Dutch consider as an open and shut case. To lift a tip of the veil: beams and curved wood were sawed in wood mills, and with multiple sawblades, so parallel.) About your remarks about Witsen. I can tell you haven't read his book. There is no doubt about what Witsen tells us. Witsen describes very, very clearly how ships were built in Amsterdam before 1671. So, read it. Do not base your thoughts on what others tell you, the others are wrong, go to the primary source and make up your own mind. Kind regards, Jules
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