Cuben shelter design.

Discussion in 'DIY & MYOG' started by Enzo, May 22, 2020.

  1. Enzo

    Enzo Thru Hiker

    I've been cluttering @gamemaster84 thread for too long so I've started this one to try and hash a design out.

    I wasn't planning on making another shelter but reading @WilliamC plans for a minimalist 2p mountain worthy shelter, and rsbtr having some seconds cuben 0.5oz on sale soured me on, and I'm furlow for another couple of weeks.

    The design criteria are,

    -Under 340g

    -Able to handle moderate wind

    -More spacious than my tramplite

    -tarp only or single skin

    - maximizes the 6 meters of cuben I've ordered.

    I'd like it to be under 340g as that's the weight of my tramplite and myog duplex tarp.
    It needs to be between these for most things, wind resistance, space etc if it doesn't do anything better than either of them it won't get used!

    The simpler the better too, more chance of it not ending up as offcuts.
    Zpacks are masters of maximising the use of cuben's fabric width in their designs, but I don't want to use the hexamid method of using tie outs to make the shape, I prefer seperate panels. And minimum number of stakes too.

    6 meters isn't a huge amount but I think I can meet my criteria with it.

    The dimensions of the tramplite ridge are 186 long by 125 at the apex, my duplex copy is 3m X 125.
    These both provide enough headroom for me, but more is of course better. It's this that causes most of the head scratching!

    I'd like to make it as slippery to wind as practical as it's being made of 0.51 cuben, so I'd like to keep the ridge hight minimised whilst maintaining an increase in livability over my tramplite.
    My duplex is more than enough with its duel pole ridge, so if I go for two poles I might choose a 115-120cm pole length, the single pole tramp is just enough at 125, and that's with a gently sloping 147cm rear panel.

    Currently I'm playing about with a duel pole design that uses a roof made with 2m of cuben cut lengthwise to make a 4m strip of 137/2 minus seam allowance so about 66cm assuming 25mm tape to make the seams.
    4 meters makes a ridge 3meters wide 125cm high.
    Head room difference between 115cm and 125cm ridge hight keeping the length constant at 3m is 386 v's 420mm, IMG_20200522_083838031.jpg IMG_20200522_083721596.jpg
    The tramplite for comparison at 1m from the centre (my reference is a 2m tall person, I'm 176) is 382mm and 964mm wide.
    Ridge hight is a compromise with wind resistance, I'm hoping those with more experience than me of bad weather in different shelters can give me their advice here?
    115 wouldn't be any better than the tramplite, but 125 would also add complexity to the door panels, 134cm at a gentle angle won't hit the floor, not much of s problem at the entrance, I like the venting there, but I'd like the opposite side to get to the deck.

    Here's another idea to try and increase headroom. Potentially minimises stakes, but I would prefer not to have any additional struts. Might be doable with just a top and bottom guyout? Also makes the door panels messy.
    I'm not wedded to any designed, so if you lot have any ideas I'd be very happy to hear them!

    Taz38 likes this.
  2. WilliamC

    WilliamC Thru Hiker

    One possibility, trading less headroom for better wind worthiness, is to lower the back pole so that you get a sloping ridge. I think the Soloplex did this.
  3. WilliamC

    WilliamC Thru Hiker

    That's what I used to think and when we first got the Dirigo I used to use poles to support the end triangle tie out. But after a bit of messing around I found that it didn't seem to make much difference in practice.
    I think it's important that the Dirigo is designed so that the guy line from the triangle continues the angle of the slope from the ridge to the tie out point, unlike the Duplex.
  4. gamemaster84

    gamemaster84 Ultralighter

    How about adding 2 carbon strips at the peaks in the same way of the main seam. It bows and gives some headroom as smd lunar does I believe.
    But I don't know that works with cuben.
  5. Rog Tallbloke

    Rog Tallbloke Thru Hiker

    The original GG "The One" did the same. Nice tent, I had one for a while. I bit tight for length, as always with this type of transverse sleeping layout. I didn't camp in exposed locations with it, partly because I had better options for bomber shelters in my gear box.


  6. Enzo

    Enzo Thru Hiker

    Yup I've been looking at 'the one', perhaps the closest thing to what I'm playing with, but less wind worthy.

    The Dirigo us definitely an inspiration. The BPL review didn't like the strut between the poles, said it flexed and that comprimised it's winter performance.
    It's too complicated for what I'm doing.

    Dunno why but I just don't like the look of different length poles. I'd like it to be able to handle changes in wind direction, but tbh it's more an esthetic consideration.

    @WilliamC the knot mini mid uses a triangular end without strut, just guyed out as you say in line with the ridge. Needs two extra stakes though.
    I think if I had a wider fabric to play with than 66cm it would make more sense.

    I could cut the 2m length of cuben offset to give 55cm peak and 75 at the ends, perhaps an end triangle 25cm high 56 wide.
    Not sure if that's big enough to warrant the work and the contortion of panels Rog alluded to?

    The ridge being so narrow I'd want to angle the poles, that means I'd be more tempted to use them point up so they can be seated in a grommet.
    I'm not a fan of pointy end up, ask me why :banghead:
    Not impossible to do handle up, but secure seats for them would add weight.
    WilliamC likes this.
  7. Rog Tallbloke

    Rog Tallbloke Thru Hiker

    @Enzo. Nitty gritty, good stuff. So many details to consider. I love the Knot mini-mid design, just wish it was 6" bigger all over for me. Maybe I could get my 16 feet of 0.51 to do it, or most of it, but there's a lot of seams... Being able to chuck the poles in handle up without any faffing with pole joiners etc is an underrated feature on it too.
    WilliamC and Enzo like this.
  8. Enzo

    Enzo Thru Hiker

    Agree, with 0.51 I'd like the door panels more sloped too.

    I guess door panel size/slope is a compromise between catching the wind with a more vertical panel and having a large panel area only suspended from potentially three points, but sloped to catch the wind less. You I think mentioned shock loads from flapping being a bigger problem than constant ish force from wind.

    It's all about compromised isn't it. I should be in an easy position as I want something between two known designs. I might be making things harder than needs be given I'm not 2m tall and I know my duplex provides enough headroom when I lie down.

    Just more is always better!
    WilliamC likes this.
  9. WilliamC

    WilliamC Thru Hiker

    @Enzo, the last copy of my design that I posted was 135cm high and 140cmx260cm with 50cm deep vestibules. The maximum material width it needs is 140cm. So, with a slight reduction in dimensions, it should be possible to do it in cuben with a slight reduction in dimension. It would only need 6 panels cutting and bonding.
    The total area as designed is a hair over 7.5 sqm. I haven't looked into how much wastage there would be when you cut it, that's a bit beyond me, but it looks to me as if it might be possible from 8m of cuben or less.
    Enzo likes this.
  10. Rog Tallbloke

    Rog Tallbloke Thru Hiker

    Well I've managed to come up with a hex3 size and shape using 7.3m DCF with 5sqft 'wastage' (it'll all be used up in reinforcements), so You'd think Enzo's 1p should use less than that.

    But we really ought to design our tents first and order the requisite material afterwards. Lol.
    Last edited: May 22, 2020
    Lempo, Enzo and WilliamC like this.
  11. WilliamC

    WilliamC Thru Hiker

    It partly depends how fussy you are about how you align the "grain" in the cuben.
    Enzo likes this.
  12. Enzo

    Enzo Thru Hiker

    Rog, if I was sensible I wouldn't be making a tent I'll hardly use, out of cuben. Buying the fabric on a whim because it was negligibly cheaper than usual, ordering it in two orders so I pay postage and import twice. And when I have shelters that already cover all my needs!

    I'm a lost cause mate lol
    tarptent, Robert P and WilliamC like this.
  13. Enzo

    Enzo Thru Hiker

    I put your design into SketchUp and measured up headroom for 2m and 1.75m people

  14. Rog Tallbloke

    Rog Tallbloke Thru Hiker

    And now we know why zpacks make 8" high bathtubs...
    gamemaster84 and WilliamC like this.
  15. gamemaster84

    gamemaster84 Ultralighter

    That's was why I thought of doing a bathub floor in my design ;)
  16. WilliamC

    WilliamC Thru Hiker

    I'm 1.77 and that looks about right from my mock up with string.
    The latest iteration has the fly widened to 148cm and the inner widened to 128cm, but the inner is separate so less than 135cm in height.
  17. Enzo

    Enzo Thru Hiker

    I look forward to seeing some pics of the finished article, preferably on a mountain :)

    I missed the referance re zpacks bathtubs?
    WilliamC likes this.
  18. Rog Tallbloke

    Rog Tallbloke Thru Hiker

    They have 8" high bathtubs to keep the breeze off you that wafts in under the 6" of clearance between ground and tarp hem that enables them to get head and toe clearance...

    Once you dial in all the parameters, the wiggle room is small on single pole shelters. That's why tallies like me have to come up with asymmetric solutions using two poles, that usually look something like a Hut1.
    Enzo likes this.
  19. Enzo

    Enzo Thru Hiker

    A pup tent would be easy cut 3m at a slight angle, spin one piece round hem the ridge and use the other 3 meters to make doors end panel etc.
    Easy peasy.
    But the entrance wouldn't be that big and the rest too small to do anything but lie down. Same kinda size as my stealth 1.

    Much prefer mids/hex to spend time in.

    Unless something turns up I think I'm sticking with my slippery half width duplex style shelter.
    At my hight, head and food hight are 520mm with it pinned. Efficient use of fabric too.
    About 130g of fabric so weight target comes down to the reinforcement, tie outs etc.p
  20. Rog Tallbloke

    Rog Tallbloke Thru Hiker

    My 16' (4.87m) of 0.51 weighs 4oz (112g) so 6m will be nearer 140g I reckon. I'm still working on the cutting plan for a pup tent, but it's not so easy as you think. Here's one option.

  21. Enzo

    Enzo Thru Hiker

    130 was just under 6 linear m of fabric minus wastage plus reinforcements. But we are talking grams, I wonder how much the tape weighs a meter?

    Your right re pup, brain fart.
  22. Enzo

    Enzo Thru Hiker

    Watching some Notch Li videos, as it's the closest thing to what I'm going to make. Looks like it's stitched together, wondering if I should do the same... Though it'd be lots more work and heavier as it still needs tape, and more cuben to tape the seams...
    @cathyjc your Howff is just tape isn't it, would you do that again? My duplex copy too and that's doing ok.

    Looking at the main ridge, it looks like it has a gentle catenary cut, can any owners confirm that?
    And what did you think of the velcro/overlapping doors
    @Clare do/did you have one? Any comments or recommendations?
  23. Clare

    Clare Thru Hiker

    I hated the velcro overlapping doors on the first version of the NotchLi. They were fine to do up from outside the tent but a real fiddle from inside. There was no way I wanted to be messing around with that in windy conditions. I had bought a Notch version1 but sent it back because of that. The new one has two way waterproof zips. Yes the main ridge has a catenary cut. The seams are sewn with two lines of stitching and taped but taped only on the inside. The tape is very fine. When I made my cuben pack the fine tape was very expensive. The cheaper stuff was a lot heavier/bulkier, so I think they have really spent quite a lot on the taping. Can photo anything that you want.

    I've had it up for a few days in the garden but not been out in it yet. It looks great. The only thing I don't like is how white/pale the cuben is because it makes the tent more conspicuous/less stealthy than the olive drab or spruce cuben that Zpacks use. I'd really like that, but hey. Its a lovely tent at around 500g. I bought it for multi week trips in the Pyrenees type stuff where I'm not worried about stealth and more interested in weight/space/wind/views.
    Enzo likes this.
  24. cathyjc

    cathyjc Thru Hiker

    Yes, If I was making another I would only tape the main seams. No stitching.
    I did stitch the zip, and taped over that - you don't really have any other option there.
    Enzo likes this.
  25. Enzo

    Enzo Thru Hiker

    I was hoping to use the zpacks style door closure, but reading people's experiences with gen one notch Li think I'll fit an aquaguard zip too.
    Might still use the zpacks closure instead of a buckle.
    Thanks for the help @Clare and @cathyjc
    cathyjc likes this.

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