Covenham-Pav-art - 11/5/17
"The Cauonham Pavilion" by Lady Linnet de Covenham. Building a 14th C pavilion.
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Mark S. Harris...AKA:..Stefan li Rous
stefan at florilegium.org
This is a report on the first phases of designing and constructing a conjectured 14th Century oblong pavilion.
The prompt to build this tent was my daughters' embarrassment at living in a mere (12ft x 14ft x 7ft tall) tent rather than a grand pavilion. The underlying requirement was to build a dwelling which functions as our summer cottage at Raglan Castle for about ten days each August. The constraints were cost, storage/stowage space, weight and authenticity; not necessarily in that order.
This is the third tent I've built. The first was a small pavilion, 10ft at the peak and nominally 5ft at the eaves. It was at best a qualified success (it lasted me a two-week Pennsic). The second was a kitchen/bathing tent 15ft long by 10ft wide. This tent built on the experience of sewing both those tents, plus owning for many years a large cotton tent made by King Sol Outdoor Stores of Toronto.
The primary exemplar for this tent is a tent depicted in a 14th Century fresco in the Palazzo Pubblico, Siena, by Simone Martini (1284-1344). The fresco shows the condottiere Guidoriccio da Fogliano riding a splendidly caparisoned horse from a siege camp to the besieged town of Montemassi. The siege camp itself, sketched from life by the artist, occupies the bottom right corner of the fresco.
The oblong tent on the left (which I will call the Martini Tent) appears to have the following salient characteristics:
· It is guyed with long lines, suggesting it hasn't got an internal spoke arrangement;
· It is made from narrow-loom fabric;
· It is ornamentally or structurally striped in black;
· It has fittings at both peaks which I will call caps;
· Its walls splay out widely from the eaves;
· Its height is just over half roof and just under half wall;
· It has three categories of lines: storm guys (from the peaks), guys (from the eaves) and brails (near the ground); Guys and brails are trifurcated into crowsfeet where they attach to the fabric;
· Rather than peg the hem of the tent directly to the ground (though such pegs could be there, out of sight), brails are attached to the walls about 15% of the way up from the ground.
· The centre of the trifurcation attaches to the seam at the eaves and in the centre of the fabric near the bottoms of the walls;
· Although the artist is at pains to show the curving effects of fabric under tension, the ridge is dead straight, suggesting a ridgepole.
My assessment of the caps is that they are leather, and the studs showing on the outside are metal fittings, which on the inside are rings for attaching the tent fabric or webbing. Based on my experience sewing a pavilion peak, flat-felled seams that come to a point are very difficult to do well. Truncating the fabric cone of the roof and attaching it to a sturdy leather cone seems an entirely reasonable solution. Producing a pair of such caps well-finished was, however, beyond my leather working capabilities and also expensive.
I considered copying the Martini tent as closely as possible, but varied the design for the following reasons:
· Height: I estimate the Martini tent at about 4m tall. The top metre would need to be bought with very long poles and longer pieces of fabric in return for, essentially, unusable space. On grounds of cost and storage/stowage I made my tent 3m tall with eaves of about the same apparent height (2m, estimated from the height of the doors), giving a proportion of 2⁄3 wall and 1⁄3 roof.
· Trifurcate crowsfeet for the brailing: I calculated that if my tent bore the strain from the peaks/ridgepole to the ground through reinforced seams, the brails would not need to be trifurcated (nor, indeed, would the guys, though I designed that in).
· To vary the height I looked at other exemplars of 14th and 15th Century oblong pavilions and noticed that the roofs are depicted as much smaller proportions of the tents' height. One reason for this could be ensuring that standing figures are displayed to advantage in front of the tents, but if you look at the oblong pavilion in the background of the image from King René's Book of Love you can see a roof that is about 40% of the height of the tent with a pitch of about 45 degrees. I used this to guide my design.
· Also, from this design, I took the straight valance (on which I intend to paint a psalm) as opposed to the scalloped valance of the Martini fresco, and chose to do without the caps at the peaks.
· To make the tent handier to carry and set up I chose to make it in five pieces: the entire roof, two walls and two doors. I designed the walls to clip onto the roof for easy assembly. This transmits the load connecting the frame to the ground through the reinforcing webbing on the roof, through a webbing loop (sewn through the tent membrane to the roof webbing), a brass swivel hook, a steel d-ring and the reinforcing webbing on the walls.
· This attachment system is sturdy and easy to use, but the design (erroneously) assumed that the attachments would not add significantly to the wall height. In practice they create a significant gap between the walls and the roof, which provides pleasant ventilation on hot days but potentially chilly draughts on cold days. This also meant that the brails near the bottoms of the walls were almost to ground level.
· One brass hook took water through by capillary action and dripped into the tent. The field expedient solution (seen on the left) was to attach a piece of linen twine to wick the water outside the wall.
· The simplest solution to some of these problems would be to remove the fittings for the brass hooks and steel D-rings and sew the walls onto the roof at the eaves.
The rectangular centre of the roof is a wedge three metres long by three metres wide and one metre from eaves to ridge made up of three lengths of fabric. The ends of the roof are half- cones three metres in diameter at the eaves and one metre tall. These cones are each made up of five sector- (pizza- slice-) shaped panels, cut off at the apex (the pointy end). The eaves (less the valence) are two metres from the ground.
The walls flare out from the eaves half a metre on each side, so that the floor is four metres from door to door, and the bases of the walls are two metres from the centre pole. Each wall wraps around the curved end of the tent and consists of seven trapezoidal panels.
I did not intend to make the wooden parts. Early in the process I ordered the wooden uprights and ridgepole, each breaking into three parts, from RL Trim of Cerne Abbas, Dorset with whom I had done business before. I ordered the pegs from HW Morgan & Sons of Mordiford in Herefordshire. Later in the process I ordered finials from Alan Calders of Leek, Staffordshire.
The frame of the tent consists of three members, each 3m long, which form three sides of a square with the ground forming the fourth side. Each of the three members breaks down into three pieces. The uprights and ridgepole are made of fir and jointed with aluminium tube, with a spike set into the tops of the uprights and corresponding holes in the ends of the ridgepole. I painted the poles and the finials in modern red paint as a cheap and quick substitute for egg tempera.
I assessed the Martini tent as likely to be made of undyed linen, and chose to regard the stripes on the Martini tent as seams with reinforcements of some sort. The Martini tent appears to be made of fabric that is comparatively narrowly woven. While narrowly-woven linen is available, as is narrowly-woven canvas (deck chair canvas), I could not find a cost-effective way to do this with narrower fabric, and chose to use Irish linen raincoat fabric dyed a neutral khaki colour, an ell wide (45ins or 1.143m). It weighs about 270gsm (8oz per square yard). The fabric is treated for water repellence. I expect the fabric to sun- bleach to a more natural colour.
I recognise that most people who use pavilions make them out of very heavy canvas, as much as 12-16oz (400-540gsm). I decided that such a heavy tent, especially when it is wet, puts an inordinate amount of stress on its frame, lines and pegs. This leads in turn to heavily built frames and big metal pegs. In the event this means that for these heavy tents any failure is a catastrophic failure. My own experience with a commercially produced wall tent made of 8oz cotton duck reinforced at the seams was that the membrane admitted only the gentlest mists of water in the worst driving Pennsic gales. A heavier tent I made out of untreated 10oz canvas showed me that a thicker membrane does not necessarily mean less misting.
It is also worth noting that heavy canvas pavilions are often made of cotton canvas. The heavier weight of cotton pavilions could compensate for cotton's comparative weakness under strain. Linen fibres have greater tensile strength than cotton fibres. Linen, unlike cotton, is stronger when it is wet. I am, however, prepared to weather a storm in someone else's heavy cotton tent should my lightweight linen confection be shredded by wind and rain.
I could not find sturdy linen (or other weatherly natural fibre) narrow wares to reinforce the seams at the price I wanted. Much cotton and linen tape is herringbone woven, which makes it too flexible for the job of stabilising and reinforcing seams; so I used synthetic woven tape 25mm (1in) wide, in royal blue and scarlet, from McCulloch and Wallis.
I machine-sewed the membrane using flat-felled seams, and then reinforced the seams on the outside of the tent with the tape, machine-sewn on. The exception to this is the seam between the roof and the valence at the eaves. This is a French seam with the excess on the outside (if it were on the inside it would bring water in by capillary action). The sewing took as long as watching all the series of the Battlestar Galactica reboot.
At the peaks of the roof I hand-sewed the tapes around a plated steel ring, creating a socket for the spike at the top of the upright. This was a substitute for the leather cap in the Martini tent. Thus, the tension of the tent went from ground through upright, steel ring, fabric tape on the roof, where it split. The guys were attached to loops on the fabric tape on the roof, and thence to a peg in the ground. The walls were attached through a tape loop on the inside of the roof, a brass hook, a steel D-ring and fabric tape on the wall seam through a loop in the tape to a rope brail and thence to a peg in the ground.
Where the end or edge of the fabric was not reinforced, such as at the top and bottom of the walls, I covered it with scarlet cotton bias tape, which I also used for loops to button the doors shut.
The two doors are secured with 50mm (2in) resin toggles made to look like bone, six on each side. The doors can roll up or be removed entirely. In the picture at the right you can see one of the doors under tension from wind. Because the door is not brailed to the ground it bellies more with the wind than the walls do. This design will be improved by attaching the top corners of the door more securely to the roof.
The doors are made of a full width of fabric, so they overlap the walls to either side. This means that even under tension there is no loss of privacy.
I assess the most likely ropes used for mediaeval tentage to have been hemp or flax. Hemp and flax make lovely ropes, but they tend to break down outdoors unless they're tarred, so I substituted manila because it wears longer. I used quarter-inch manila line for all the guys and brails. Nominal quarter-inch is a lot thicker than a 12.5mm, and my peg-maker (who also made my tensioning toggles) drilled the toggles out extra wide.
I know of no evidence for wooden tensioning toggles in the Middle Ages, but I'm not enough of a Girl Guide to trust my tension to the appropriate sort of knot. Indeed, my lines are almost nowhere knotted and almost everywhere spliced because splices are at least potentially stronger than knots. Also, they look much smarter, especially when whipped with some fine linen twine. That said, I know absolutely nothing about mediaeval knots, splices or whipping.
The use of reinforced seams as the main loadbearing parts of the membrane left a bit of slack in the linen fabric. This makes it clearer to me why crowsfeet are so nearly ubiquitous in representations of mediaeval tents. Because I erected in haste I went without crowsfeet, though I did sew in loops to attach them to the roof. I will splice them in this year. In my experience freely-running crowsfeet run through rings rather than fixed to the lines give the tent too much play.
I did much of the setup myself, with a helper for hoisting the frame to the vertical. I made a simple guide for the pegs: a rope with a loop at one end to peg into the location of the upright, and loops at the correct distances to peg the brails and guys.
First I assembled the ridgepole on the ground to function as a guide for the spacing of the two uprights, and drove a peg in at each end, which I'll call the home pegs. With my simple guide attached to each home peg I drove the pegs for the brails and guys. Then I spliced the brails and guys onto the tent roof. Because I hadn't spliced them on with time available for making up the crows' feet I spliced each line only to one loop on the roof.
Then I spread my roof upside-down on the ground and put the ridgepole inside. Then I assembled the top two-thirds of the uprights flat on the ground, and put the spikes through the sockets on the ridgepole, then through the small openings at the twin peaks of the tent. The bottoms of the uprights were roughly at the home pegs. I folded half the roof over so that I had a two-dimensional version of the roof flat on the ground. I fastened the finials onto the spikes. I attached storm guys to the finials, and knocked a couple of long storm guys in any old how, so that when the tent went up it would have some tension on one side.
Then my sturdy helper and I hoisted the frame upright, ourselves shrouded inside the roof. This was easy with only the top two metres of the uprights to manoeuvre.
Then we hoiked the top two thirds of the uprights onto the bottom third. I then left one pole teetering against the tension of the two any-old-how storm guys, while my helper held the other. I looped some guy ropes around some guy pegs here and there so that the roof was more or less stable. Then with effusive thanks I let my helper go back to setting up his own camp.
Once the guys were pegged and tensioned I hooked the rings at the top of the wall panels onto the hooks at the top of each wall seam, and then spliced brail ropes unto the bottom of each wall seam. Then I pegged down the brail ropes. Because the hardware hung the walls lower than I'd planned, the walls form a bit of a puddle hem on the ground. This is cosmetically not what I'd intended, but operationally not a problem.
Then I used the hooks at the top of the door panels to attach them to the rings at the tops of the door jambs. This was insufficiently taut and will need a bit of re-engineering before I use the tent again. You can see that the top corner of the door flaps a bit, and will need its own hook to make it shipshape and Bristol fashion. Once the doors were on I could judge better positions for the storm guys and drive them in properly.
Apart from the drips and niggles I've mentioned above there were two significant failures.
I mentioned above that instead of using a leather cap I had used a plated steel ring to which I'd sewed the tapes, which met at each peak. This certainly distributed the strain, but not well enough. A small rip opened in the fabric beside one peak. You can see it in the photograph below. It did not threaten to get any bigger over the course of a week's camping, but it will have to be patched both to repair and to reinforce this area.
The other is the one place where there is significant contact between the frame and the membrane: the ridgepole. Capillary action at that point of contact brings water through the fabric, and some dripped inside. To prevent this I mean to create a second layer of roof above the ridgepole, almost a long, skinny tent, suspended from the finials. This will keep the fabric in contact with the ridgepole dry, and eliminate those drips. Where did that idea come from? From the ridges of the oblong pavilions in many mediaeval illustrations, including the above illustration from King René's Book of Love. What appears to be a decorative ridge could, I surmise, be intended to prevent just this sort of leak.
One of the biggest problems I had in setting up was too small a plot of land. Because I have such a spare internal framework I need (like the owner of the Martini tent) to spread my guy ropes out widely. This first time out I was beside a path and had to drive my pegs short -- closer to the centre pole than was optimal. On the other side I had a steep down slope which again forced me to drive pegs short. I compensated in some places by hitching my guy ropes to railings and, in some places, pegging them to higher ground; but one part of the tent in particular was a bit slack as a result. This meant that it flapped in a breeze, and I had to look sharp on occasion to keep the valence from coming in above the wall.
The hardest thing about this tent was designing it. The best thing about it is that while it is very roomy, it is also very light and packs down into a comparatively small space.
The greyhound is optional.
Copyright 2016 by Lynette Nusbacher. <Sca at nusbacher.com>. Permission is granted for republication in SCA-related publications, provided the author is credited. Addresses change, but a reasonable attempt should be made to ensure that the author is notified of the publication and if possible receives a copy.
If this article is reprinted in a publication, please place a notice in the publication that you found this article in the Florilegium. I would also appreciate an email to myself, so that I can track which articles are being reprinted. Thanks. -Stefan.