I promised you a full report on my experimental tent after a field trial at Pennsic. Here it is.
There were several experiments in play at the same time. I’ll try to address them all.
Q: Supposing it’s true, as some have claimed, that there were no internal frames in medieval tents. No perimeter poles. No spokes. Is a ropes-only tent a good idea?
A: Maybe, but not at Pennsic! Immediately upon arrival, we were asked by the horrified camp steward to shorten the long shoulder guys that held the tent open. This caused the tent to sag and to flap in the wind. I bought some rattan poles and tried to prop up some of the corner ropes with makeshift perimeter poles. That only helped somewhat. Tents being fairly transparent to sound, I could hear passers-by calling it things like "the spider tent from hell."
Q: Many period illustrations show tripled "crow's foot" rope attachments. Are they important?
A: Yes. The shoulder guys in a ropes-only design are the biggest point of failure. We didn’t triple them, and I regret it. One of our corner grommets ripped out twice, although it probably would have held if the tent had been properly taut.
Q: Shouldn’t one use jute or hemp ropes instead of synthetic?
A: Yes. But, be prepared for them to shrink and stretch wildly if they get wet. The manilla hemp ropes we used shrank noticeably in the rain. To avoid ripping out the guy lines, we had to loosen all the ropes when there was rain on the horizon. But, that added slack contributed to the flapping in the freshening breeze, which was a problem in itself. Next time, I’m using nylon ropes.
Q: A large tarp already has most of what you want in a pavilion. It has a reinforced hem. It has grommets all around. It's already assembled, instead of coming in thin strips. Etc. In theory, all you have to do is lay out your plan just so, and you can preserve all that. Does it work in practice?
A: Yes. I was able to convert a 30’x30’ tarp into a 13x20 pavilion in one day, using only a household sewing machine. It was not expensive, and had the great benefit that there were no seams over most of the roof. This method definitely has promise. Having the doors in the ends, the way they are on some belled wedges, worked fine, and allowed for cross-ventilation.
Q: The prototype was made from a white, heavy-duty, woven polyethylene tarp. How did that work out?
A: What would be really cool is if you could do the same trick with a canvas tarp, saving all the extra labor and half the extra cost of a scratch-built tent. The drawbacks are that large canvas tarps (a) are not made of premium (Sunforger) canvas, (b) come in an ugly mud-brown color, and (c) don't come in handy sizes. But, that could all change if somebody started selling better tarps.
As expected, the plastic fabric was light, waterproof, and cheap. The steel ridge cable relieved any longitudinal stress on the roof, so there was no sign that the tent wanted to rip in half (as some had warned). It didn’t breathe through the fabric at all, but the two doors gave pretty good ventilation. Although there were five of us sleeping in it, there was no noticeable condensation on the interior walls. The volume was large enough to disperse the moisture from our breath. It was no more sweltering than any other tent with closed sides. In the heat of the day, we stayed under large open-sided canopies in the encampment’s common area.
However, the big drawback of the synthetic fabric was its SLICKNESS. Nothing would stick to it! I used commercial Seam Sealer to caulk up the few seams, and they leaked anyway. I tried a number of sealing tapes, including some exotic and expensive ones, to reinforce and seal the seams, and they all peeled off. The best I found was a kind of industrial duct tape (how fitting!), but even that would not hold. So, the seam overlays, like the decorative stripes laid down along the other edges to match, peeled off and left the tent looking rather shabby.
I have seen a "Tarp Tape" advertised for sale. It claims to make a strong, permanent, and water-tight seal on poly tarps. It’s expensive, comes in short rolls, and was sold out when I tried to buy it. But, I may try again. Without some way to seal and strengthen the few seams used in this design, this prototype is headed for the landfill.
6) Curtain Rods
Q: Since the roof and walls were all of a piece, how did you hang mosquito netting over the doors? A: I bought bridal tulle and made curtains, with curtain rods of 3/4" PVC pipe. At the shoulder corners on either side of the door, I put grommets on the inside and tied the pipe to them. (Specifically, I ran a long cord through the pipe and tied it to a shorter cord on the opposite corner.) This had the positive side effect of spreading the fabric corners apart, so that the only sides of the tent that didn’t sag were the ends with the doors. Hooray! This kept the roof from funneling rain water into the doorway.
(In fact, it worked so well, I have to wonder why I couldn’t put similar rods on every side and dispense with the authentic but universally hated ropes.)
The netting had a tendency to billow in the wind, reducing its effectiveness somewhat. Luckily, this was not a bad year for mosquitoes at Pennsic.
Back to the drawing board!