Skin on Frame Housing the yurt gets a roof

Progress on the yurt continues.  Much of the progress is imperceptible to anyone but myself but the progress is there.  As it turns out, my initial suspicion that my first yurt would be a prototype for working the kinks out of the design turned out to be true. So let me share what Ive discovered so far.

 I got the crown on the central ring of the yurt.  I used some kayak rib stock, 1/4 inch by 3/4 inch white oak, socketed into the central ring and lashed together with tarred seine twine. The idea behind the crown is that it will be open under normal conditions but covered when it is raining or heat needs to be kept in the yurt.
Another discovery I made after the initial assembly of the yurt was that for the sake of getting a good setup it helped to trace a circle on the ground first before erecting the walls so that the walls would form a perfect circle.  The perfect circle is essential so that all the rafters are the same distance from the central ring.
I also discovered that I had much more wood in the central ring than I needed and so it was too heavy and difficult to get into position when no help was available. What I did to remedy the weight problem was to cut some of the extra wood away from the center of the ring.  It was way stronger than it needed to be. 

 The next step was to cut out some fabric for the roof.  It took me some time to work out the trigonometry for the roof cover shape, but I did it.  But I have learned to distrust theory and test with an actual life size cover.  The other reason for getting the cover in place was that a series of rain storms were coming into the area and that would be a good test to see how the cover would stand up to the wind.

Heres an inside shot of the cover.  The wind lifted it some and pushed it off center.  Part of the problem is that the shape of the cover is like a pie with a wedge cut out of it and the edges adjacent to the missing wedge get pulled together and glued or sewn resulting in the desired pyramidal shape.
The cover is made out of some sort of vinyl covered fabric that is used for advertising banners.  A friend gave me a bunch of these banners and I cut them up to fit the roof. The fabric has two problems.  One is that it is very heavy and the other is that it is very stiff.  The combination of weight and stiffness makes it very difficult to pull this stuff up on the roof.  The weight also works against its portability.
On the plus side, the cover survived the storm and did not get blown off.  I also discovered that once again, there is nothing like building something to test a design because until you do, its next to impossible to know what sort of problems the design has.  So far, none of the design elements have been complete failures but lots of them can use improvement.
The list so far.
The wall battens are slightly too flexible.  A bit more stiffness is advisable even at the expense of greater weight.
The skin is too stiff and heavy.  Lighter weight is advisable.
Other commitments have kept me away from the yurt, but the learning continues.  I will continue to post whenever there is progress or even when design ideas fail.

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Yurt Report Wind Test

Two nights ago, the yurt underwent a spontaneous wind test.  A front with wind gusts up to 50mph moved through the area.  The bushes and trees were rattling against the fences and roofs and making a spectacular amount of noise.  And then I realized that I had recently skinned up the yurt.  It had survived the previous winter without problems but that was as a bare frame.  With the skin on, the wind would be able to exert more pressure on it.  I was tempted to drive out to the shop and check the yurt right away but decided to wait till morning to assess the damage if any.

Next morning I drove to the shop.  The first thing I saw was the flag down on the ground.  This wasnt a good sign. 

I went to the back of the shop with some trepidation but there was the yurt, still standing, albeit with the roof cover partly blown off.  This was no big deal since I had not sewn the final seam and the cover had a tendency to get blown off even in a light wind.

A few of the roof poles had also lost their moorings and fallen to the ground. I suspect what happened that made the poles fall down was that the flexing of the wall in the wind distorted the round shape of the walls into an oval, popping off the tension band and allowing the top of the wall to bow out to where the roof poles were able to pull loose.

The tension band, the green rope, is inside the wall instead of outside, apparently just rolled over the top of the wall.

Putting the yurt back together took maybe 15 minutes. So the test was useful, revealed some more of how the yurt works.  I already knew that the wall was a little too flexible.  Now I knew another reason why it should be a little stiffer, to not distort in a strong wind and allow the roof poles to come loose.  Also the roof covering needs better tiedowns, something I just hadnt bothered with yet.

Oh, and I untangled the flag and got it back to the top of the pole.

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The Camping Yurt

I built a ten foot diameter yurt suitable for camping.  The ten foot diameter seemed suitably large for comfort but not so large as to provide a transportation problem and also not so large as to overflow available camping spots. Our intent was to give it a good workout in Kings Canyon National Park.  By and large, it worked out with minor problems.  Pictures and comment below.

This shot was meant to show how small the yurt looks in a natural setting.  It looked much larger when I first set it up in the driveway of our house. We left the roof cover off so we could look at the stars at night.

Here is a picture of the yurt in the afternoon when the sun is hitting it.  We peeled back the wall for better air circulation.

Here is the yurt with the roof cover on.  We may still sew darts into the overhanging portion of the roof to take up the wrinkles.

After we got kicked out of Kings Canyon due to government shutdown, we found a camping spot in Sequoia National Forest right next to a Jeffrey pine.

Here is a longer shot of the yurt to show its size in proportion to the pines.

And then it snowed.  Clouds moved in in the morning and we put the roof cover on.  I had not yet made a smoke hole cover so a plastic tarp had to do the job.  The snow all melted once the sun came out.

A closeup on the tension band that holds the top of the wall in against the pressure of the roof poles.

And a closeup of the roof pole to wall junction.

The tarp leaked a little since laid flat over the smokehole ring to which I had not yet added any arch.  Here I have added some willow twigs to remedy that problem.

All in all, we were pretty happy with how the yurt behaved.  Next addition, some flooring to isolate the bedding from the ground and a small wood stove for heat.

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Yurt Design Canvas Shrinkage

Canvas shrinks.  I knew that. So when I designed the roof pattern for the yurt, I should have allowed for shrinkage but didnt.  Oh well, nothing that cant be fixed with a little more sewing.
Not only didnt I allow for shrinkage in the roof, I also didnt realize that the canvas shrinks unevenly, more along the length of the material than across it.  Something to be conscious of next time.
Now that I think of it,  I doubt that I could plan for shrinkage in any sort of exact way since the shrinkage is non-isotropic.  I suppose I could just make a roof cover uniformly oversize, then when it shrinks, regardless of whether it does it evenly or not, it would still be large enough to do the job.
For now, not having tried to it yet, I am leaning toward pre-shrinking the canvas.  Unroll however much canvas I need, hose it down, dry it in the sun, then cut it up and sew it into whatever shape I need. Everything I havent tried yet sounds like a good idea.  Whether it actually is, doing it will tell.
Meanwhile, some before and after shrunken roof cover pictures.

Before: the yurt roof cover on its maiden voyage in Kings Canyon National Park. I trimmed the fabric so there would be about 8 inches of overhang.  Sewing the seam at the edge reduced that by about an inch.  Other than the wrinkles which I hadnt dealt with yet, not bad.

After: Overhang of the roof fabric has been reduced to about 4 inches at the max and two inches at the minimum.  The wall fabric likewise has shrunk some top to bottom and side to side. Time to make some corrections. Canvas work is not an exact science.

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What Killed the Kayak Aleut Version Akutan Alaska

Akutan, Alaska is an island in the Aleutians and once a place where people paddled kayaks as a part of making a living.  Nowadays the biggest industry on the island is a fish processing plant.  Trawlers scrape the bottom of the ocean for fish and bring them to the processing plant to have them turned into product suitable for sale in the lower 48. The Aleut population of the island actually has very little to do with the fish plant other than extracting rent from them.  Still, the kayak as a tool for hunting, fishing and whaling is no longer in use.

The fish plant at Akutan.
Photo courtesy of Kurt Schmidt

The big  rusty things are doors on a trawl. Picture a net like a large sock with one of these doors on either side sliding along the bottom and funneling fish into the sock.  Nothing escapes.
Human added for scale.

Iron weights hold the bottom of the net close to the bottom of the ocean.

Nets.

Nets.

Bye, bye Akutan Kayaks.

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The Twelve Foot Yurt

The ten foot yurt has had a few outings in the past few years.  It worked well but I thought it could use a little more floor space in conditions where we wanted to use part of it as a kitchen. So I set to work on the design of a twelve foot version.

A twelve foot diameter, vs. a ten foot diameter would give this yurt 44 percent more floor space.  I decided to keep wall height the same so that I could re-use the existing wall lattice, needing only to add another 6 foot section of wall to bring the circumference up to 37 feet from 31 feet.  

I tried to figure out ways to re-use the existing roof parts, but that was not possible.  Still, re-using the existing wall parts and door cut down considerably on the total amount of work.

So on to some pictures.

Heres the sewing studio for the roof. I tried sewing the roof on the floor of the living room at first, but the large hunk of canvas kept colliding with various furniture.  Having the large flat area of our driveway to rassle the canvas was a big plus. The other thing I learned from the ten foot yurt was to soak the canvas in water and let it dry to shrink it before cutting and sewing it.  Shrinkage was mostly along the length of the canvas with very little across the width so trying to get a good fit without pre-shrinking the canvas would have been a challenge.

 This photo is of the trial assembly of the yurt in back of the shop. Looks good enough.

 What you are looking at here is the extension of the wall canvas joined to the existing wall canvas from the ten foot yurt.

 I also decided to add a skirt to the interior of the yurt to minimize the amount of sand blowing into the yurt in windy weather.

 And this is the tono or roof ring.  I made the roof poles a little over long so minor changes in length wouldnt have them pulling out of their sockets.

 Heres the twelve foot yurt pitched in front of the original 16 foot yurt.  Note the difference in roof pitch.  I wanted to experiment with a lower pitch on the twelve footer to keep interior volume down for easier heating.  The new pitch was 30 degrees vs. about 39 degrees for the 16 footer.  A lower roof also makes for easier setup of the roof.

 I also decided to make a door frame for the door cover, an upgrade from a simple flap that hung over the door but was a nuisance to go in and out of.  The assembly of the parts is tongue and groove for reasonable stability combined with ease of disassembly.

 Once I was done, I dragged all the yurt parts outside to weigh them.  Total weight about 198 pounds.  Not suitable for backpacking but OK for car camping.

And here, the yurt deployed in the Mojave National preserve.  We wanted an open roof for star viewing at night but rigged a table cloth for shade during the day.  

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Yurt or Skin on Frame Portable Dwelling

I havent done much boat building lately since I have been busy working on a yurt.  Though this blog is supposed to be all about skin on frame boats, I thought it would be OK to indulge in some related skin on frame construction, namely, the yurt or portable dwelling.
The idea of building a yurt came to me after last years October camping trip.  We were pretty far south but at high elevation and so we encountered snow and cold nights at times.  We had an adequate tent and warm sleeping bags but the sun went down early each day and then stayed away for twelve hours so that once it got dark there was little to do but crawl into the bags and listen to books on our mp3 players.  Camp fires and eating are usually good camping entertainments, but most campsites have fire rings that keep the heat of the fire away from the camper and otherwise hamper what should be a good entertainment.  Likewise, cooking food when it is near freezing is possible but once the food is done, it gets cold in a hurry and then you have to clean up in the dark and cold.
So the idea of a tent that was big enough to stand up in and build a fire or set up a camp stove in and cook in and eat in, all in comfort and warmth wormed its way into my consciousness.  The idea of a tipi came to mind, but those require long poles and a lot of canvas and would add a lot of bulk to an already bulky camping load. So then I thought about yurts.  And as a little research showed, there were lots of articles on the topic on the internet. 
In addition, my neighbor, Tim Anderson had built a yurt and so I could use him as a technical adviser.  So off I went on the yurt adventure.  I quickly found out when doing the research that everyone builds yurts their own way and nobody seems to tell you much about general principles like how strong to make the walls or what the pitch of the roof should be, whether the thing will hold up to a snow load, heavy winds and so on.  And so I decided to build a prototype yurt that could sit behind the shop.  I would use it to work out the design details and once that was done, I would build a smaller more portable and lightweight yurt for camping.
So here goes with the photos.

 The target diameter of the yurt is 16 feet so I needed to construct 48 feet of wall.  Circumference of a circles is pi times diameter of the circle, remember?

Heres a closer up view of the wall with another semi-nomadic structure behind it.  Nomadic if movable by fork lift fits your definition of nomadic.  In any case, for the sake of convenience the wall of a yurt is usually constructed in sections so that each section is of a size that is easy to lift and not too wide to transport.

And heres a shot that tries to show the curvature of the lattice wall.  Hard to visualize this sort of thing until you actually build the wall.

Intersections of the wall slats are held together with clinched nails, that is nails whose tips are bent over and hammered down and buried in the wood.

Heres a view of the junction from the other side where the tip of the nail is buried in the slat.

And here is one section of the wall, all folded up into a 30 inch wide section.  When unfolded, this represents 24 feet of wall.

When the two sections of wall are joined as shown here (temporary joint made with clamps) the wall is complete.  And the 96 inch long slats at an angle make the wall 72 inches tall.

The other two ends of the two wall sections will get connected to a door frame, not yet built.  Note alternating colors of wood.  I had enough old redwood deck boards to make almost the whole wall but had to buy a few extra doug fir two by fours to top off the number.  The redwood was free and light.  The doug fir was about ten dollars total and stronger than the redwood but also heavier.  We will see how they hold up over time.
Stay tuned for door frame, roof and canvas cover yet to come.

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Baidarka Chair

What do you do with an old baidarka (kayak) once it starts falling apart?  Why you make a chair out of it.
I dont know the details behind this picture other than that it came to me from people living in or once living in the Aleutians. I wont mention their names just in case they would rather not be named. On the other hand, if they feel like they would like to be named, I would be glad to name them.
The question here is whether making a chair out of a baidarka is considered creative re-use or an act of vandalism, or worse yet, sacrilegious destruction of a valuable cultural artifact.  Who knows.  Probably the kayak was falling apart and someone did some creative re-use.
Regardless of what is going on here, lets try to identify some baidarka parts that might have gone into this chair. The skinny rods that form the back look like hull stringers.  The larger upright pieces of wood that form the sides of the back look like sections of the stern parts of gunwales.  The rest of the pieces are hard to identify other than that they might be deck beams.  And the seat looks like a piece of kayak skin. 
Rock on.

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The Yurt Gets a Door and other improvements

The sixteen foot yurt has lived for over a year without a door.  But now that it has a stove, I discovered that the yurt loses heat quickly without a door.  Actually, I already knew that, but since my improvements on the yurt tend to be on a just in time basis, having a source of heat made a door imperative.  The first stab at a door was to just staple some pieces of vinyl banner to the door frame, but in a wind they were practically useless.  So the next step was to build a door with a wooden frame, something more substantial that would actually keep the drafts out.

The stove, blazing away.

The stove pipe now has a hat which keeps the rain out of the pipe but the smoke hole needs some flashing around the pipe so the tarp that covers the hole in the rain doesnt get melted by the heat from the stove pipe.

One of my neighbors at the shop has donated a chair, a mockup for the console/chair for the boat he is building.

And here is the new door, a wooden frame with a piece of plastic banner stapled to the front of it.

And here is a view of the door from the outside. Love that shanty-town look.

Closeup on the latch mechanism. The string goes through a hole on the top and another on the bottom.  When outside the door, you pull the top string to pull up the latch or the bottom string to pull the latch down. 

By the way, the yurt has now withstood 65 mile an hour winds and survived.  Little by little, small improvements make it a better structure.  Surprisingly, the most challenging task was how to keep the roof in place since wind going over the top of the roof creates a vacuum which wants to lift the roof cover up and then blow it off.  An improved tiedown system did the job.

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