"Floating" frame timbers

[Hakai43]

Here is the stern framing layout for HMB Endeavour (1764), according to KH Marquardt. Notice that many of the upper timbers are independently spaced from the adjacent futtocks that they would customarily be laminated with. This seems weak, with these timbers secured only by the planking, clamps or lodge knees. I can see that this arrangement allows for the needed spacing of windows and ports, etc. But it seems that many of the frames could only be laminated by their lower members, with the other timbers added after all were in place. 
 

Also, the stern-most timbers seem to curve in two dimensions - perhaps they are cant frames, likely at that point.

 

Any observations would be appreciated!

[Pirate adam]

This is normal.  The frames you are referring to as floating are simply single frames vs. the other frames which are doubled.  Keep in mind the futtocks are still bolted to the one below with chocks or scarphs just like all the others.  Surely this is not as strong as a doubled frame, but it gives 2 advantages.  Firstly lighter weight high in the ship where weight isn't desirable.  Secondly the gaps between frames were meant to help keep the wood dry.  Keep in mind these were still enormous pieces of wood in real life.  Those frames will be more delicate when you are building the model, but you will find the assembly to be plenty strong once combined with the various wales, planking, etc.  You can find lots of examples on build logs on the site including the various Swan class models.

 

I suspect the frames become cant frames starting at station 23, but I couldn't say with the information in the drawing.

 

Adam

[Kenchington]

7 hours ago, Hakai43 said:

the stern framing layout for HMB Endeavour (1764), according to KH Marquardt. Notice that many of the upper timbers are independently spaced from the adjacent futtocks that they would customarily be laminated with

I don't know what evidence there is for the frame of Endeavour specifically. Perhaps she had as many timbers in paired bends as that illustration indicates but in that era many another ship, built following English methods, had far fewer -- and not just high in the hull but from the first futtocks upwards. (The French, in contrast, had long-since adopted the 19th-Century approach for their warships, with the timbers in each bend fastened to one another. That gave more strength for the same amount of timber but at the cost of needing more weight in iron bolts.)

 

7 hours ago, Hakai43 said:

This seems weak, with these timbers secured only by the planking, clamps or lodge knees.

Yes. But that was how boats and ships had been built for centuries and how the smallest wooden ones still are (unless they are glued together with modern chemicals).

 

7 hours ago, Hakai43 said:

it seems that many of the frames could only be laminated by their lower members, with the other timbers added after all were in place. 

Into the mid-18th Century, the practice in English Royal dockyards was to get all of the floors bolted in place before any futtocks were added. At that point, there was no way to drive bolts between adjacent floors and futtocks, as they were far too close together. All connections between them were via the planking and footwaling. To anyone familiar with later ship structures, that looks weird. But it is how it was done.

 

7 hours ago, Hakai43 said:

the stern-most timbers seem to curve in two dimensions - perhaps they are cant frames, likely at that point.

Of course many timbers curved in three dimensions. But there should not have been any cants in the after parts of such a ship. Cants were needed where the bow curved around towards the stem -- a curve in the design waterlines (not that the waterlines were drawn out in that era). There was no similar curvature in the stern, though there were sharper bends in the sections and what would now be the buttock lines. Canting the timbers would not have helped with framing those.

 

 

Also:

 

1 hour ago, Pirate adam said:

the futtocks are still bolted to the one below with chocks or scarphs

The attachment of the head of one timber to the heel of the next above is a bit of a vexed question. There certainly is evidence that some 18th-Century vessels were built with scarphing chocks, which were presumably fastened to the timbers above and below. Then there is mention in contemporary sources of eking pieces, used where the main timbers didn't quite curve enough, leaving a gap that could be filled by something that looked a lot like a scarphing chock but was an infill in low-cost construction rather than an expensive strengthening of a high-cost ship. And there were plenty of vessels built with the heel of one timber not even reaching to the head of the one below, let alone fastened to it.

 

High-end warship construction produced relatively neat and regular structures but many a smaller vessel had framing that was decidedly irregular. The textbooks didn't show that, of course, but archaeological records of how real ships actually were do -- if the archaeologists took the time to study what was in front of them.

 

 

Trevor 

[Hakai43]

Thank you Adam and Trevor. That's valuable information I wish I'd had before starting framing (frames 14 through 20 of my stern cross-section are installed.  See the photo of its current status.) Now I'll have to give some thought to how to proceed on 21 through 26.
 

Regarding aft cant frames, I've included the lines for Endeavour, showing that as a Whitby coal cat, she was essentially a barge with stern lines quite similar to those in the bow below the waterline. Trever - considering that, would you still think aft cant frames were unlikely?

[Hakai43]

1 hour ago, Kenchington said:

 

Into the mid-18th Century, the practice in English Royal dockyards was to get all of the floors bolted in place before any futtocks were added. At that point, there was no way to drive bolts between adjacent floors and futtocks, as they were far too close together. All connections between them were via the planking and footwaling. To anyone familiar with later ship structures, that looks weird. But it is how it was done.

 

 

If frames were built that way (rather than laid out and bolted together on a floor and then raised as a unit) it would seem more accurate, by using a series of station moulds connected by ribbands, as is done for bent-frame boatbuilding. Do you think they were built like that?

 

If I had done it that way, aligning each futtock to the ribbands, I suspect I wouldn't have the deviations that I do have in my frames which require shimming. Also, I could have done at least rough inside and outside beveling to each piece at it went in, using the ribbands for reference. I don't think I want to re-do those eight frames, but perhaps I could go that route for 21 to 26, especially if I'm departing from strictly two-lamination frames.

[Kenchington]

9 hours ago, Hakai43 said:

Do you think they were built like that?

How ships' hulls were put together varied through time, from place to place and with the type of ship or shipwright. At one time, the Dutch had an approach in which they laid the bottom planks (with temporary fastenings) then put in the floors afterwards. The circa 1750 New England schooner that we partially excavated 40 years ago looked like the top timbers towards the stern had been added after the planking there, though I could not be sure. The main bend had futtocks treenailed together, though I would guess each timber was added to the growing structure, rather than the later approach of constructing a whole frame and then raising it into position. (As few other bends had the timbers fastened together, there was plenty of space to work an auger and swing a mallet around the main bend.) Warship construction in the major dockyards was a whole other business -- same basic concepts but far more exacting.

 

Certainly, there was much use of (temporary) ribbands to tie the developing structure together until the wales, clamps and other permanent longitudinal elements were in place.

 

There does seem to have been some conceptual link between designed bends and the fastening together of futtocks. English warship draughts of the 18th Century typically had only the bends for every third floor drawn out. On the actual ship, every third set of futtocks seems to have been fastened together, with "filling frames" (which may not have been a contemporary term) in between. In the dockyards, the intermediate futtocks were probably lofted by interpolating from the draughts. In contrast, small vessels like our schooner could have only the main bend and a few "mould frames" (again a modern term) fastened together. With those set up, and ribbands run around them, the shape of the other timbers may have been taken off the ribbands, rather than from a table of offsets -- though I doubt there is any contemporary evidence either way.

 

But all of that concerns full-size construction. Unless you are documenting archaeological records in 3D or seeking to display a part-built vessel, there's not much need to replicate real-world complications. The classic Navy Board models show a very beautiful but very stylized version of 17th-Century ship structure!

 

Trevor

[Kenchington]

10 hours ago, Hakai43 said:

Trever - considering that, would you still think aft cant frames were unlikely?

I'll have to get back to that question this evening!

[Kenchington]

20 hours ago, Hakai43 said:

Trever - considering that, would you still think aft cant frames were unlikely?

All of the contemporary textbooks described the structures of major warships and the similar, large merchantmen. I am confident that the Whitby colliers were different in at least details but I have no idea what the differences were. I don't even know whether there is any evidence that historians and archaeologists might examine. That being so, I will answer through the underlying principles of mid-18th Century English warship construction, even though that will be misleading somewhere.

 

With that caveat:

 

Bows were framed (in so far as the timbers that the planking was fastened to) with pieces that rose up and out from the centreline structure (of keel, keelson, stem etc.). Through to 1700 and a bit later, dockyard practice had a knighthead either side of the stem, with hawse pieces next. In a bluff-bowed collier, their outboard faces would have faced almost straight ahead. The foremost "square frame" (not a contemporary term) formed the outer edges of the beakhead bulkhead, in those vessels which had one. The cants framed the curve in between. However, they were nothing like the 19th-Century cant frames. In plan view, each of those look much like one-half of a  square frame but set at an angle to the centreline. In contrast, the cants of 1700 (in plan view) reached out at right angles to the centreline. What made them different was that each piece was twisted around the axis of its own length (hence "cant", meaning twisted). That twist minimized the need for bevelling -- a process which turns very expensive compass timber into wood shavings.

 

The English Royal dockyards adopted something closer to 19th-Century cants around 1715 but I expect the old way was maintained by distant shipwrights building smaller vessels. How long the Whitby shipwrights stuck with tried and true, I cannot say (and very likely nobody else can either).

 

So much for the bows and the cants. The framing of sterns was quite different and maintained principles that made sense with 16th-Century square tucks. The principal pieces were the transoms, set transversely across the post. In warship construction, the highest (the wing transom) was at the level of the lower deck and the main wale. That ran nearly straight from starboard to larboard. With a round-tuck stern, the transoms below had to be increasingly curved and then angled. Low down in the hull, a transom would have needed trees that had grown with deeply-veed shapes and yet large thicknesses. As those were so rare as to be unobtainable, something else was needed. But higher up, where the hull was more broadly curved, the stern was framed with transverse transoms.

 

So the short answer is that cants were not needed to frame the broad buttocks of a collier because those were not framed with timbers rising upwards from the keel but with transoms reaching (more or less) horizontally out from the post. At least, that would be so if warship-like framing structure was used.

 

Cants were not needed below the lowest transom either, because what set the height of the lowest one was the narrowness of the run (need to provide a clean water flow to the rudder) and there the shape of the hull was not very far off parallel to the centreline, so that only moderate bevelling was needed.

 

 

I don't want to be drawn into criticism of the work of any author who is not here to defend his efforts. I am certainly not going to pass judgement on a book that I have not read. However, to reconcile what I have just written with the framing diagram posted yesterday, I will note that my version would have the forward ends of the lower transoms extend to maybe Station 20, if they were to match the hull lines, whereas the framing diagram shows them reaching only to Station 26. Maybe Whitby shipwrights did use such short transoms and, if they did, they may have had to cant some of the timbers in the stern, rather than bevelling away half of the wood. But that would take me into the differences between warship and collier structures and, once again, I have no information on those.

 

Trevor

[Hakai43]

Thanks Trevor. A lot to consider in relation to where I go from here to finish framing Endeavour from station 21 to 26. 
 

I will go with the process of building frames in individual pieces from the floors up, fitting each piece against ribbands attached to temporary 1/4 " plywood moulds at 20, 23 and 26. These will follow Marquardt's diagram fairly closely in single or double laminations. I am hoping that the beveling on each piece can be done before installation, guided by the ribband bevels. At 26 the fashion piece will mate to the seven transom ends, perhaps canted. Whether the intermediate members are canted or perpendicular remains to be seen.

 

I've also been thinking about the difficulty shipwrights must have had in finding and stocking oak timbers to fit these curved requirements, sometimes in three dimensions. It must have required transporting logs in as large pieces as possible to fill unforeseen needs. Very heavy and bulky pieces carried long distances.

[Kenchington]

19 minutes ago, Hakai43 said:

It must have required transporting logs in as large pieces as possible to fill unforeseen needs. Very heavy and bulky pieces carried long distances.

At some times and in some places, shipwrights took the moulds into the woods and chose trees that suited particular pieces that they needed. A century and more after Endeavour, the schooner builders of Essex, Massachusetts sent sets of moulds to contractors in Delaware (the nearest remaining source of suitable white oak). The contractors chose the trees and had their workmen rough out the required pieces, which were transported north by sea.

 

It was a whole different process from going to a local lumber yard and buying planks sawn to standard dimensions -- though plank and deals could be bought that way, if not sawn in the shipyard.

 

Trevor