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Post by jules on Mar 8, 2014 18:33:34 GMT
L.S. Not a new topic, but I have a question about the framing of Vasa. Clayton included a drawing of Stolt and a description of the framing of Vasa by Fred, in his report on building his Vasa-model at www.wasadream.com. _  The drawing of Stolt Clayton
showed in his report. When I combine these two sources with a third source, a drawing of Stolt at page 432 of VASA I, it seems to me that Vasa was built in a peculiar way, not corresponding with the 'normal' dutch building method. Let me explain what I mean. In 'normal' dutch ship building an overlap of the frame parts only occurs, broadly, at the bilge of the ship and at the level of the lower gundeck. For the rest of the build, large openings between the frame parts were left unfilled. I hope the sketch below shows what I mean. In the sketch I removed the inner and outer planking at the nearest side. This to show the frame parts with the openings between them. A wellknown 17th century drawing of Sturckenburg shows these openings as well. In contracts the overlap of the frame parts is usually specified as being at least 7 feet or so, which leaves a lot of open space between the keel and the first futtocks, and the first futtocks and the third futtocks. When I look at the two drawings of Stolt, it looks like almost all the space between the futtocks is filled with extra frame parts: almost no spaces between the futtocks are left unfilled, resulting in an almost complete wooden wall at the side of the ship. Prior to the building of his beautiful 1:50 Vasa-model, Clayton used the first two sources, the information gathered from Stolt and Fred, to draw a framing plan. He also arrived at a filled in ships side, filling the spaces between the futtocks with extra frame parts, resulting in the aforementioned wooden wall. And, what's more, Clayton also filled in the spaces between the floor timbers. This resulted in a completely filled up framing from keel to rail over the whole length of the hull. My question is, is this really the case? Is Vasa's framing completely filled up from keel to rail? Since the two drawings of the framing by Stolt only show sections of the ship, I wonder if this filling up-method was used all over the ship. If so, Vasa's framing was built extremely heavy. This, combined with the very heavy, over dimensioned, constructions in the ships interior, would have resulted in a great increase in empty weight of the ship. On top of that, the extra frame parts between the third futtocks, those above the waterline, increase the weight in a position where you would want to save weight, not add it. This must have affected the ship's stability in a negative way. I hope someone can help. Jules Attachments:
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Post by Clayton on Mar 9, 2014 15:28:33 GMT
Hello Jules! While it is true that I filled in the spaces between the floor timbers on my model, I did not build a solid wooden wall above the turn of the bilge. I wonder if some of my pictures are misleading. Here are a couple that show the framing with spaces:   I wonder if how Vasa is done, with a nearly solid wall of wood, is actually more normal than we have been led to believe of the northern method? Or in other words if it is just that the tradition of building a more or less solid wall of framing was a normality of the shipyards that the two Dutch shipbuilders who built Vasa were trained in? I am sure there were subtle differences in how the northern method (or any building method for that matter) was carried out depending on who the builders were. Cheers! Clayton |
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Post by fredhocker on Mar 10, 2014 8:40:47 GMT
We have gone to a great deal of trouble to map all of the framing (Kroum Batchvarov did this over a two-year period),including radar scanning, endoscopes, and digital recording, and can say that over most of the lower hull, it is effectively a solid wall. The lower ends of the first futtocks stop just short of the keel, and so span almost the entire bottom, for example. Where the framing is visible at air strakes in the hold, orlop and lower gundeck, there are few gaps. In between, probing between the ceiling strakes has shown that there are no significant gaps below the lower gundeck, but that there are some in the upper works. Some of these are associated with the framing of the gunports, but others are not. It is also the case that the framing timbers are not made in consistent lengths, so that the first or second futtocks do not all end at the same height and the overlaps vary in length, and thus what gaps there are vary in size. This type of irregularity is not what one sees in treatises, where order is imposed on a chaotic world, but it is what one sees in reality. In all of the 17th-century Dutch-built wrecks I have studied, including warships, East Indiamen and inland craft, the framing is consistently irregular in scantling and arrangement, although the basic idea is what one sees in the treatises. The frames also do not sit parallel to each other or square to the keel, but tend to gradually tilt in towards amidships near the ends. Eva Marie's drawing of the framing amidships is largely accurate for that location.
We estimate that the total weight of the empty hull is at least half of its eventual total displacement, which is a large amount of timber. At the time of the sinking, the panel of experts convened to discuss the loss came to the conclusion that the problem was that the ship was too heavily built in its upper works for the amount of diaplacement, and modern analysis more or less confirms this. The framing is not the main problem, however, it is the over-designed rider and deck beam system which contributes most to the high centre of gravity. The frames in the upper part of the hull are not that thick for a ship this size, about the same as one would find in a merchant ship in this range, but the beams and riders are huge and very closely spaced compared to later ships. For example, Vasa's beams and riders are larger in scantling, more numerous in elements and more closely spaced than the same structures in Kronan of 1676, which displaced twice as much.
Clayton and I had a long exchange of emails when he was aatarting the framing on his model, because to copy the exact "system" used on Vasa would be maddening for a model builder, and what we arrived at was a buildable compromise that suggests the basic pattern of the original and its regularity. Also, at that point, we had only just started the frame documentation project, and so could not give him detailed information.
Fred
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Post by fredhocker on Mar 10, 2014 9:53:20 GMT
By chance, I am recording framing details today for the section of ship side we are building for stress testing. I can report that the only significant gaps in the framing occur at the level of the lower gundeck - the framing is solid above and below this. The gaps are for the most part not very large, but about every fifth or sixth frame, there is a gap between the lower and upper futtocks ofabout a meter, with a gap of over two meters in one case. Still, most of the timbering in this area is solid. Once I finish the drawing of this section, I will post it here.
A detailed framing plan of the whole ship will be included in Vasa III, which we have already started working on.
Fred
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Post by fredhocker on Mar 10, 2014 10:35:10 GMT
Oops, forgot about the hals issue.
There is a heavy frame at the widest part of the bottom, the hals in Dutch terms, and this is forward of the middle of the length but not exactly at a third of the length. We are pretty sure there are no fasteners between this floor timber and the futtocks either side of it.
Fred
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Post by jules on Mar 10, 2014 12:54:32 GMT
Thank you Clayton for posting the pictures of your frames. Very clear. One other reason why I asked this question is that the Vasa-model in the museum's diorama shows a complete wooden wall above the lower wales. Only at the top, the futtocks are shown with spaces between them. According to Fred's answer this is an accurate depiction. I am surprised by the filling out of the bottom with the second futtocks though. Sure, as Fred says, the portrayal of framing in treatises is highly stylized. As is the portrayal of framing in Navy Board ship models. An irregular overlap of the frame parts is a given in actual ship building. Archaeology shows us so. The shipwrights, being highly practical men of course, must have been sensible people: why waste good wood on getting a nice regular view of the frames, which will be boarded up later anyway. But, in the case of Vasa it looks like someone got cold feet with regard to the ships sturdiness. The overlap of the consecutive frame parts seems to be exagerated. In a 'certer' of a 172 foot ship of 1629 an overlap of only 4 foot is prescribed (Van Yk, 1697, p. 159). This is probably a merchant man, but still... Seven foot (almost 2 meters) is a common overlap in big ships of Vasa-size. The dense packing of wood we see in Vasa, is something I never came across reading archaeological reports on dutch shipbuilding. Have I missed something Fred, or is Vasa really an exception? Dutch ships were known for their light build. The english later (around 1670) say that English ships seem impenetrable for cannonballs compared to the dutch ships. When we compare dutch frame thickness with english frame thickness, we have to conclude that the dutch actually did build lighter; this in favour of manoeuvrability and lower depth. On the other hand we have testimonies that cannonballs bounced of the sides of De Ruyter's Zeven Provincien, what implies that even the lighter dutch build was more than sufficient. Or was Vasa an exponent of a new way of enhancing the strength of a ship? Maybe the extra timber was introduced to make the ship impenetrable for cannonballs. Fred's stress tests should be conclusive on that matter. It would be interesting though to compare the results of these tests with the results from stress tests performed on a ship's side that is built according to the lighter, less packed, method. Fred, thank you for sharing your thoughts on the weight distribution in Vasa and its relation to the ship's stability. I do not know if it ever came up in this forum that Vasa is not built according to a certain rule Van Yk mentions in 1697. At the risk that I tread on ground already covered: Van Yk states that no ship should be build higher than twice its depth. The depth being measured at the main frame (hals), from the top of the keel to the top of the end of the beam of the lower gun deck; the height measured from the top of the keel to the top of the railing. When we look at the drawing of the main frame of Vasa, we can see that Vasa is built much higher. The depth to height ratio is almost 1:2,15 instead of Van Yk's maximum of 1:2. The excessive height is probably caused by the height of the second gundeck. This deck is even higher than the lower gundeck. When we look at later 'certers' for threedeckers, we see that the second deck is lower than the first deck. Building threedeckers was something new in 1628, maybe the main building parameters still had to be determined for this type of ship. It's a pitty Van Yk does not explain where his rule originated from. Maybe the lessons learned from Vasa translated into new shipbuilding rules. Fred, looking forward to the post of the framing section. Great! But how sad we have to wait untill Vasa III for all the details of the framing  Keep up the good work! Regards, Jules |
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Post by fredhocker on Mar 10, 2014 15:58:10 GMT
Here are some rendered images of the section of ship side we are building, which is at the level of the lower gundeck near amidships (the gunport is the fifth from the bow). Note that there are spaces between the frames from about the gunports up, except behind the ends of the deck beams, where the timbering is solid. The spaces get filled in towards the upper part of the upper gundeck by the top timbers, but their ends are even more uneven than the upper ends of the second futtocks seen here. This drawing is as up to date as possible, since I measured the frames in this area this afternoon. The ship is tall for its depth indeed, which can be seen on the inside as well - there is too much headroom in the gundecks. The lower surfaces of the beams are 1.80-1.90 m above the deck in the upper gundeck, and up to 1.70 m in the lower gundeck. This is much more than needed for a crew averaging only 1.67 m in height. No idea why it is so.    |
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Post by jules on Mar 10, 2014 20:30:48 GMT
Great stuff Fred. Thank you very much.
I suppose the top timbers, or at least the bottom ends, will be placed in the gaps of your test section?
Any idea when the tests will be executed?
Regards,
Jules
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Post by fredhocker on Mar 11, 2014 7:58:08 GMT
The top timbers do not extend this far down, so they will not be included. They only come down into the upper part of the upper gundeck.
The section will be the subject of two sets of tests. In the first set, scheduled for May, the section will be mounted on a large stress rig to investigate its stiffness, particularly the stiffness of the joint between the beam and side. This test will go through several iterations, as we test several variables, such as the different sizes of hanging knee used on the beams, and the variation in joint tightness due to shrinkage. We will start with all joints tight, the as-built configuration, and then gradually loosen the waterway-to-beam joint and the joinery between the beam and its rider and knees, by cutting away some of the wood to mirror the effects of shrinkage. We think that most of the joint load is currently falling on the bolts, and that the complex lapped notches are no longer doing their job, which is allowing the hull to twist. The results of these tests, corrected for the slightly different mechanical properties of the PEG-treated original timber, can then be used to develop a Finite Element Model of the whole ship to determine how the hull distributes stress, so we can design a new support structure for it.
Once the stress testing is done, the section will be taken up to the Bofors proving range in Karlskrona and used as a target for assessing the ballistic performance of the ship's guns - we will shoot it with a replica 24-pounder demi-cannon that we cast last fall. This test is currently scheduled for October.
Fred
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Post by jules on Mar 11, 2014 13:30:28 GMT
Thank you for the update Fred.
Thought I was finally coming to grips with the matter of framing, when I got surprised again. So the large openings occur at the place where it really matters, above and next to the gun ports of the lower gundeck. This is the place that, in most contracts for warships, is explicitly mentioned: the demand being that the framing had to be closed at this height of the ship. If the overlap of the futtocks was too short here, extra wood chucks ('kalven' in dutch) had to be placed in the remaining openings.
At first I thought the side of Vasa was almost completely closed with wood, as can be seen in the diorama-model. But this does not seem to be the case. Openings do occur more often than I thought and at other places than I thought.
Am I right in saying that Vasa has an extra fourth tier of futtocks in comparison with the three tiers with other ships? In short: Vasa has a 9-part frame: floor timber, second-, third- fourth- and fifth futtock; other ships have a 7-part frame: floor timber, second-, third- and fourth futtock. The 9-part frame, with the taking into account of a substantial overlap of the adjacent frame parts, would result in an almost closed wooden wall with sparse openings.
Van Yk only gives 5- or 7-part frames (Van Yk, 1697, p. 69). I think Witsen, for big ships, only mentions 7-part frames.
I guess I have to wait for Kroum's work in Vasa III to get the complete picture.
The testing program is very interesting. To set a finite element model of the complete ship as your goal, sounds very ambitious. Interesting stuff! This must be a first in archaeology.
The ballistic testing program sounds very interesting as well. Tom Ward will surely look forward to that test.
Thanks again Fred.
Regards,
Jules
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Post by fredhocker on Mar 12, 2014 8:53:07 GMT
Jules,
That's right, the framing is most open in the area most likely to be hit by a cannonball! I will let everybody know what the consequences of that are in the fall, since we will aim at both the open and closed areas of framing to compare damage.
The open area is where the lower gundeck waterway is bolted through the side, so it provides some of the strength in this area that one would get from solid framing, but not in the same way.
Yes, it looks like the basic framing plan is based on nine-part frames, if we include the top timbers. There are a fair number of chocks/kalven in the system, mostly to make up the difference when frame timbers were short, and I think the filling pieces behind the beam ends are chocks in some cases.
The finite element model is part of the process of designing a new support structure for the hull, since the current one does not correspond very well to the weight/stress distribution in the ship.
Fred
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Post by jules on Mar 12, 2014 11:14:23 GMT
Hi Fred, Thanks for expanding on the subject. It's getting clearer and clearer for me now. Still surprising though. I include the Sturckenburg-drawing from the Amsterdam Scheepvaartmuseum, to show what the 'normal' framing looked like in the 1650s (approximately). It is a drawing of a later date and of a smaller ship than Vasa, but can, in my opinion, still be considered as a good representation of the 'normal' practice in Vasa's days.  In the drawing we can see that the futtocks are closely packed at the range of the first row of gunports. Something we do not see at Vasa; at least, in the small section Fred so thoroughly checked. Just some thoughts on this subject. Was Vasa preliminary intended as a twodecker? When they started building they were focusing on a two decked vessel and prepared the wood accordingly. When it was later decided that a decked over waist was more appropriate, an extra row of top timbers was stuck between the 'old' top timbers to create the extra height. Or do all the structural surprises originate from a more banal given: a shortage of wood with the appropriate length? Interesting information about the chocks behind the second gundeck beam ends. I remember a discussion with Hoving about this subject. Hoving almost always shows beam ends that are placed between the futtocks in his reconstructions (as Vos did with his Batavia), the beam ends of the second deck protrude till they reach the outer planking. Am I right in saying that the second gundeck beams of Vasa do not protrude? Or is this just a local phenomenon, only to be seen in the short fragment Fred checked? Can anybody help? Thanks, Jules PS. The Sturckenburg drawing is a scan of the worked up drawing Franklin included in his 'Navy Board Ship Models'. I hope he doesn't mind. The A3-copy I bought from the museum is far too faint to scan. |
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Post by fredhocker on Mar 13, 2014 9:27:51 GMT
The deck beams in the lower gundeck all seem to end against the interior of the framing, as do the beams of the upper gundeck and orlop. The only exception is beam 22 on the upper gundeck, which goes all the way through the side so that it can function as the dale for the main bilge pump. I have not gone through the upper gundeck to see if they filled the spaces behind the beam ends with chocks, but the timbers which fill the space behind the lower gundeck beams can also reach the equivalent space in the deck above. Will check at some point and let you know.
I have seen other archaeologicl examples where the beam ends protrude into the space between the frames, but mostly on smaller, more lightly built craft.
There is no evidence to suggest that the deck arrangement was changed during construction. The flush upper deck without open waist is integral with the rest of the ship, as far as I can tell. It may be that the framing arrangement is a response to the timber. The framing was sourced locally, and Swedish oaks do not grow as tall as the ones farther south.
Fred
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Post by jules on Mar 13, 2014 15:36:39 GMT
Thanks Fred.
Very clear for the orlop, the lower gundeck and the upper gundeck. You do not mention the beams of the third deck. I suppose they finish against the futtocks/toptimbers as well and do not protrude.
I am also curious about the placement of the knees of the great cabin (kajuit) on the upper gundeck. Witsen describes that the knees of the cabin of his pinas are placed between the top futtocks; probably to save space. (Witsen 1671, p. 79, I, "4. De knies tusschen de stutten lang 5 voet). The 'Hollandischer Zweidecker'-model of 1670 shows no knees in the cabin, so the description of Witsen seems to be accurate (Winter, Tafel IV and photo 30). Winter neither shows knees in the hut and the top hut.
It would be a good thing to know how this was executed with Vasa.
And guys, don't leave it all to Fred this time. I believe the most of you have built models of Vasa, some of you even from scratch, so some of you must have solved this matter long time ago. It would be nice to know what your experiences with these constructions were. Please join in.
Kind regards,
Jules
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Post by fredhocker on Mar 14, 2014 9:18:19 GMT
I can answer how things are done on the ship, especially in areas not accessible to the public, but others will have to say how you handle it as a modelling challenge! The hanging knees in the cabins are indeed between the futtocks as Witsen says. I do not think that this is to save space, but to provide a smooth interior surface sutable for panelling, etc. The vertical arms of the knees are hidden behind the ceiling, so that the interior wall in the cabins is flush. For the cabins, we have adopted the English convention of naming (the Swedish form essentially follows the Dutch). From the bottom up, we refer to the great cabin, the upper cabin and the coach (Swedish is kajutan, hytten, bovenhytten). Here is a picture that shows the knee arrangement on the beams in the upper cabin. Not the best angle, but you should be able to see how the knees are fastened to the after face of the beams, pass through notches in the uppermost ceiling plank, and then lie between the futtocks. Fred  |
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In the sketch I removed the inner and outer planking at the nearest side. This to show the frame parts with the openings between them. A wellknown 17th century drawing of Sturckenburg shows these openings as well.
Keep up the good work!
