Making a Tent Inner

Why ?

One of the reasons I’ve turned over so many tents in the quest for a perfect setup, is that the inners that tend to come with tents, particularly pyramid tents (“mids”) aren’t roomy enough. Let me explain…

In a typical mid, for example the MLD Duomid or Liteway PyraOmm Duo, you’re looking at an overall pitch area of around 270cm x 160cm. Generally for this size shelter you have the choice of a single or double inner.

A single inner sits behind the central pole supporting the tent, so at most you get about 80cm of width/depth, but you get around 230cm of length which is plenty. I like a bit more width in an inner though, and coupled with this is the fact that the vestibule is the other half of the tent, and I don’t actually need that much.

A double inner doesn’t solve the problem. Whether these work with a central pole (requiring the inner to be pitched first) or with an A-frame, a double inner tends to use most of the 160cm width/depth leaving very little vestibule. So a double inner is simultaneously too much inner and too little vestibule.

Now, in the last paragraph I mentioned A-frames, which obviously could be used with a smaller inner too. Indeed, if I could just get hold of one, any inner deeper than 80cm should fit the bill – I could go anything up to 100cm and still have enough, although not excessive, vestibule space.

Having made a tent the year before, I felt more confident that if I ever needed an inner I could make one. And so, when I was looking at getting back in the Duomid sized pyramid game, I decided I would probably be able to pick the fly I wanted, and simply make an inner to my requirements. This meant I had more choice of shelters.

Indeed, as the inners that come with these shelters tend to be mesh, I needn’t be constrained by that either and could make whatever combination of mesh and solid fabric I wanted.

So I did.

The Design

The chosen mid was a Liteway PyraOmm Duo, measuring 272cm x 164cm and 130cm high. The equivalent from MLD, the Duomid measures 280cm x 172cm and 140cm high at the time of writing (they’ve been steadily getting bigger over the years).

So, an inner measuring something like 230cm x 90cm and 120cm high would be about right. This would allow me a 50-60cm vestibule and enough clearance behind the inner.

Indeed, once I allowed for the fact that I tend to pitch a shelter like this at least 5cm off the ground at the sides, I could go to 125cm high. The above diagram shows my thinking, and how I measured things so that it would work with either a sloping trekking pole support, or an A-frame. Pole length isn’t a huge issue as I have one pair of poles that extends to 160cm, although, even so I’d be using an A-frame joining piece.

Prototyping

As I did when I made my tent, I validated the design and geometry by making a scale mock-up using squared paper. I carefully made scale versions of the individual side panels and the one piece bathtub, and then joined them together to mimic what would happen when I sewed the real thing together.

Before the build, the key decision I had to make was how to form the corners of the bathtub, and I read various threads on this subject. Ultimately, I hadn’t decided when I made the first paper mock up, and just sort of found myself forming a triangular tab with the excess material that results from folding a rectangular sheet into a bathtub shape. (More images with the real thing further down should make this clearer).

I ended up with a bathtub corner mechanism I was pretty happy with, and didn’t need to worry anymore about whether or not I would put stiffeners in to maintain vertical bathtub sides.

The side panels forming the walls of the inner went on easily and there’s not much to write about here.

Materials

I decided to use the following to make the inner – all my supplies, apart from the yellow fabric (which I bought off a friend who had it going spare) came from Ripstop By the Roll:

• Bathtub – 1.6 oz HyperD PU4000
• Lower solid panel (yellow) – Hilleberg inner tent fabric
• Mesh – 0.9 oz Noseeum mesh
• Upper solid panel (orange) – 1.1 oz Ripstop Nylon, uncalendared
• Door zippers – YKK #3 coil zipper with YKK #3 double pull coil sliders
• Thread – Gutermann Mara 70 in spectra yellow, blaze orange and black
• Grosgrain – MIL-SPEC 3/4″ Nylon Grosgrain Ribbon in black (I think)
• Corner adjusters – Linelok 3

I bought all this lot the year before when I made my tent, and bought enough for two inners – in case I messed the first one up.

Making the Bathtub

I cut off a piece of the bathtub material measuring 124cm wide by 264cm long. This was calculated as follows:

• Length: floor length + height of bathtub for each end + seam allowance for each end = 230 + 15 + 15 + 2 = 2 = 264
• Width: floor width + height of bathtub for each side + seam allowance for each side = 90 + 15 + 15 + 2 = 2 = 124

I hemmed all around.

Then I folded the sides up, which left a triangle of excess fabric sticking out. At this point I started playing around with struts for the corners again, but ultimately decided to continue without.

I then folded the sticky-out point of this triangle back down to the bottom corner to form a symmetrical triangular tab. I needed to put cuts in the top of the side fabric to make this work.

To these 4 corner tabs, I sewed a loop of grosgrain (top and bottom) with a linelok 3 threaded on. A simple piece of cord then fit through the Linelok and could be adjusted for tying the bathtub out to either one of the fly’s stakes or to its own stake.

At this point, I pitched the PyraOmm in the garden again and tried the bathtub for size. It seemed about right.

Making the Side Panels

The key to the side panels was working out where to put the divides between the 3 types of fabric. I was aiming for enough of the thicker Hilleberg inner fabric (yellow) at the bottom of the sides to block drafts without making it too enclosed. It simply needed to be a height that would cover me lying down, including propping myself up on an elbow.

Similarly for the top, but here the solid fabric was mainly used because I thought it would be better to form the point of the pyramid with that rather than mesh. So I chose a depth that looked about right. The mesh portion was just whatever was left.

To each of the panel heights I needed to add seam allowance to and bottom.

I attached each panel to the next with a double-rolled seam. This was probably more robust than I needed, but it looked ok. Wherever possible I used thread the same colour as the fabric so that my dodgy stitching wouldn’t be too obvious.

Typically I started with the biggest pieces – so at the bottom. The top panel was generally added last.

Below the picture shows the top panel being added for the first line of stitching. This would then be rolled again and double stitched flat.

Finished sides were laid out on the floor to re-measure before starting to join them to each other.

On the back panel, I decided to add a triangular pocket at each end.

Unlike the sides (because the front and back sloped at different angles), the front and back were the only two symmetrical panels. For these I generally folded in half to make measuring of the next piece being attached easier and to ensure that I retained symmetry as far as possible.

Finished rear panel. I also added a mesh pocket at the top – for a light. Unfortunately, I placed it too high and lost most of it when forming the apex of the inner.

Making the Entrance

Making the non-opening sides was relatively straightforward – it was all down to the measuring. But now came the one truly tricky technical bit – adding the zipper.

I mulled various configurations:

• A “J” zipper, curving around – simply to do as long as I could get it flat and cope with the curve.
• An inverted “T” zipper. This would have meant 3 separate zippers – two at the bottom and one vertical in the middle, or a more complicated arrangement where the top half of the bottom zippers curve around to form the central vertical zipper in a single piece on each side. The bottom half of the lower zipper would then just be a separate half zipper. This felt wasteful, and also heavily reliant on me forming the corners properly. 3F UL Gear use (or certainly did use) this technique on their inners. I guess it’s fine if you’re making several, as that spare half zipper won’t go to waste.
• A rainbow zipper – like a “J” zipper but even more curve! I’ve had inners with these before, and don’t like the door trailing around on the floor when open.
• A “V” shape lying on its side. I could do this as two straight zippers, and the only challenge was creating a stop point so that the zipper didn’t fly off the open ends. This is ultimately what I went for.

The idea was sound, but the sewing wasn’t.

In this case I chose to sew the zipper tape onto the inner, then unzip the zipper and cut through the fabric. I would then fold down the fabric into a neat seam. This went wrong during the cutting stage and I was left with a jagged and wonky set of fabric ends that couldn’t be tamed into nice neat seams. So after trying and failing, I simply left them hanging, accepting that they would fray and need further work. In doing do I did trim away as much of the excess as I could so that the straggly ends didn’t get stuck in the zipper itself.

After using for a couple of nights I managed to pull one of the zipper sliders off and had to reattach it in the field. I effected a more permanent repair when I got home, but this left a bit of a gap at the pointed end of the door. I sewed a flap of yellow fabric that could cover that gap.

The Finished Inner

It looked ok when I set it up in the garden for the first time. A bit uneven in places, but far better than I expected, and certainly good enough for something that will be hidden under a flysheet.

I put the tent over it and climbed in to get a feel for if it was going to work.

…and then repositioned the trekking poles into an A-frame – which is how I would be expecting to use it most of the time.

Using it in the Field

I took the new inner, along with the PyraOmm Duo, on my walk of the South Downs Way in March 2022, using it on both wild and campsite camps.

And on St Swithun’s Way in July.

And on my two part walk of the Yorkshire Wolds Way. Unfortunately, I don’t have any photos clearly showing the inner from that trip.

In total, at the time of writing, in January 2023, I’ve used the inner for a total of 13 nights – 9 on wild camps and 4 on campsites. Enough to get a feel for how well it works and what I need to improve upon in the next one.

It’s been out in some windy and rainy conditions and done well.

Lessons Learned

Overall, I was pretty happy with what I turned out, but use in the field has brought some possible ideas for improvement to mind.

1. Increasing the amount of solid fabric on the back and sides – purely to retain more warmth.
2. Possibly compensating with a wider strip of mesh on the front. Don’t know, haven’t decided yet.
3. I felt the 1.1oz ripstop nylon I used for the solid peak wasn’t great – very flimsy, slippery and difficult to sew. Although colour-wise it was exactly what I wanted, I’d probably have been better off using Hilleberg inner tent fabric which I did for the lower solid parts (yellow).
4. I made a right hash of the zip. The idea was fine in itself, but the execution was terrible.
5. I’ll probably eliminate the pockets I built into the lower solid panels – they sag a lot and aren’t really very useful.

One thing I did learn, though was that making an inner was way easier than making an outer tent – mainly because the pieces involved are much smaller and hence, more manageable – I could cut them out more precisely on my dining table, whereas the panels for the tent I made were bigger than the table in at least one dimension usually.

Second, because I was building each side of the inner from a collection of smaller pieces, I measured again and again and again and again and again, until I was heartily sick of measuring. I found I only had small differences between panels that were supposed to be the same size. It matters a bit less on an inner anyway as no one really sees it!

Third, I was a lot more confident in the geometry of the inner, and this showed in the final product, even though I didn’t make a prototype out of cheap fabric like I did for the tent.

I was most happy with the bathtub corners. I’d do this again.

When I do the zip on the Mark II, I think I’ll feel more confident attaching it directly to the edge of the panels concerned, making the finishing of the zip edges easier (like the way you’d make a zipped pouch). This just needs a bit more measuring to work out the position of the zip. It will be hardest on the vertical one as that will need to be in a bit from the edge – so I will have to plan a front panel with a side strip to attach that side of the zip too. As it will be a straight line that shouldn’t be too hard.

The second version will incorporate more solid fabric on the back and sides for warmth. The main challenge for the second go will be sourcing the yellow fabric, and unless I can find someone with some, obtained in one of Hilleberg’s fabric oddments packages, like I did last time, I’ll have to look at an alternative fabric.