Tarp size: is 10 x 4,5 enough???

The 10 ft length would be long enough , but the cuben will only end up being 51.5" wide after you the hem the the edges of the 54" width.

The half pyramid pitch might work as long as the winds didn't turn the wrong direction. Also, attaching the kilt to the opening would be awkward and it would still leave you vulnerable in a major blow.

The MLD Cuben Monk Tarp is the same width as what you'd end up with. I've seen threads here on BPL about the Cuben Monk. You might want to do a BPL search and see what those with experience with it have to say.

Good luck with the project.

I can't see 2.25 on either side of you being enough. Most tarps are much more than that. And if you are looking for flexibility with a flat tarp, a tarp that narrow will not be very flexible.

Do you carry an umbrella? In a strong wind, rain will blow down the length of a tarp, and only a very well anchored rain skirt will withstand that. An umbrella would work great with a flat tarp. Of course you can pitch the tarp with the wind hitting the side, but winds can change directions.

Steve

Do mockup of that 10×4.5 tarp in Polycro or some otber cheap material.
Unless you are built like a toothpick,I think you will find out quickly that 4.5" is not nearly enough width for a good storm pitch with no other form of protection (bivy,etc)

Remember,if the weather is that nasty, you will need some space for your gear and enough space all around to keep spray/ splashback st bay… My educated guess is that 6' wide will be the smallest you will find usefull.

Thats about 1 ounce more of material in Cuben. IMHO, it "stupid light" to deprive yourself of the material needed to actually allow the shelter to do its job properly, just to save an ounce or some $$ on material. Do it right the first time..;) Good luck on your tarp project!

A mockup would be a great idea. Here is a thread showing pictures from Steven Evans' (of Suluk46) tarp of similar size:

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=21233

Steve. You are certainly right about 2’25” on both sides not being enough, but…… I’m not thinking of using the ordinary A-frame pitch when weather turns bad. That’s why I thought about the half-pyramid, like in the picture of Steven’s MLD tarp (thanks John for linking this thread). With bad weather I would always pitch the long 10’ side right on the ground and facing the wind, but I know the wind can (and will) change more often than desirable, and that’s where the skirt comes in handy (to cover the large open gap at the front). And no, I don’t carry an umbrella, but the skirt should do the job (I hope).

Monte. I hadn’t thought about hemming the edges (which would mean losing another 1.5”) but I am fully aware of the fact that the 4’3” width -ON ITS OWN- will not be enough (not even close). Having said so, I had hoped that matching the tarp with the 4’5” x 2’ skirt would do the trick. This would give a combined width of about 6’1” (considering the overlap). On the other hand, as you say, I think the length of 10’ should suit me well (after having seen the pictures in the post John linked to). I believe the MLD tarp is only 4.3’ x 8’ and knowing Steven Evans is as tall as I am, the 10’ length should do (looking at his picture). With regards to attaching the skirt to the opening, I have several ideas about how to do this without too many problems – it obviously should be very secure and I don’t want the skirt to be flapping around, but I don’t think this would be a major problem. It’s more about the question of the combined width of both items (tarp + skirt) being enough. BTW I’ll certainly do the BPL-search you recommend.

Jimmer, Thanks for suggesting doing a mockup. I’ve already done a few, very small scale, paper mockups and I want to do some more on a larger scale with a more resistant carton paper, but it’s a good idea to make a “real world” mockup (thinking of using some very thin painters’ polyethylene drop cloth). I do not want to go “stupid light” for the sake of cutting weight or $$$$ (as a matter of fact, I have plenty of Cuben at home, so I won’t have to spend one penny more), but…… if I can make use of my skirt which I’ll be carrying anyhow, why not lose some weight (and work by avoiding having to sew/bond an extra strip to the regular length). And no, I’m certainly NOT like a toothpick :(.

John, Once again, thanks for the link. I'll try to import one of the pics from that thread (if I can). Maybe that gives a better idea about what would happen if the MLD tarp would be combined with a 4'5" x 2' skirt.

Edited to upload one of the pictures from referred thread. Imagine the large gap to be (partially) covered with mentioned skirt and consider that the tarp would be one foot longer on both sides. Would that do the trick???

I was afraid this was one of those situations you see down in the MYOG forum starting with
"If I only have 3 yards of Cuben"…

As to using the kilt as " door or screen, thats what I intend to do with my Poncho when Solimid and flat tarps in really bad weather. Every little bit helps!

Good luck and get some mockup pics. A 6ft 3inch dude under a 10×4.5 polycro tarp in a storm pitch would be very interesting to see…

10' length is okay, but that is 5" shorter on the width than my poncho. Small tarps are good with a bivy, particularly for head-end coverage with a waterproof bivy for less claustrophobic camping, cooking and changing clothes in bad weather. 8×10 is more like it and that will give room for alternate pitches or even two campers. I see a lean-to pitch (long side to ground) as a prayerful means of shelter– praying that the wind doesn't shift :)

I think between your rain skirt and taking advantage of natural protection, you could make it work. But I also think there will be times when you wish you had carried 2 more oz for a much larger tarp

I have a 6.5 x 10 foot cuben tarp that I have set-up in half pyramid and used a rain skirt and an umbrella to block the front. There is a lot of room inside, however, it can still be easy to run against the walls. As others pointed out, with a 4.5 foot wide tarp, or smaller, that room will be reduced… Whether that’s big enough or not will depend on you… I know that Monte is using a smaller tarp (although, not quite as narrow as yours) but he is planning on using it in area’s with not much rain… (You can check out his tarp in the SUL section here on BPL). Here is a photo of mine:

Also, here is a post I did on this set-up on my blog…

9' x 7' would be my choice for one person.

Hi Jimmer. > Good luck and get some mockup pics. A 6ft 3inch dude under a 10×4.5 polycro tarp in a storm pitch would be very interesting to see…< When I get a bit of spare time, I’ll start working on this and, if possible, upload some pictures.

Dale. I think you have to do a lot of praying if you want to do a lean-to set-up and not get wet. As said before, the wind will change – not always, but the chance is very big if you’re thinking about doing a long-distance walk over several weeks. Obviously, a 10×8 tarp gives an awful lot of room and a lot more protection, but this is not about making a larger tarp (which I could, because I have plenty of CF). I want to find out whether I can make a combined width of 6ft (tarp + skirt) work under inclement situations. Another approach, without having to add anything to the regular width of the CF, could be changing my groundsheet into a bivy by adding a breathable top, but that’s a different kettle of fish.

John.
> I think between your rain skirt and taking advantage of natural protection, you could make it work < Thanks for giving me a bit of hope :).
> I also think there will be times when you wish you had carried 2 more oz for a much larger tarp < I suppose you’re right about this and I guess I won’t know whether it’s possible to make it work until I actually made and tried it.

Hi Stick, It’s very interesting to see the picture of your set-up (including the rain-skirt & umbrella). I can see where the (little) gap, at the top of the pole, will allow water to come in.

I’ve thought about a different system to attach both the tarp and skirt to the top of the pole. I plan to make a small hole in both pieces at about 1 ½ or 2 inches from the edge (in the center) and poke the tip of the pole through these holes. This would create an overlap of 3” to 4”, which I think should be enough, considering that I’d first put the top through the skirt and afterwards through the tarp. That would leave the tarp on top of the skirt and since the dominant wind (and rain) will come from the long (10’), rear part (which is orientated windward), this should -I hope- be enough to avoid water coming in.

Furthermore, I plan to not raise the front end as much as in your set-up, so the bottom part of the skirt will be lower, thus avoiding the need (????) of the umbrella there. BTW. I saw Monte´s thread in the SUL forum; very interesting tarp – beautifully made. I don’t think I can make mine with such a professional look. Joe did a very good job.

JohnS. Yes, I know that a 9×7 tarp would be a better choice, but I want to make use of something I already carry with me, getting dual (or multiple) use out of my gear.

"I’ve thought about a different system to attach both the tarp and skirt to the top of the pole. I plan to make a small hole in both pieces at about 1 ½ or 2 inches from the edge (in the center) and poke the tip of the pole through these holes. This would create an overlap of 3” to 4”, which I think should be enough, considering that I’d first put the top through the skirt and afterwards through the tarp. That would leave the tarp on top of the skirt and since the dominant wind (and rain) will come from the long (10’), rear part (which is orientated windward), this should -I hope- be enough to avoid water coming in."

I guess it wouldn't hurt to try, but I'm not sure if putting a hole in the tarp for the pole to go through would be a great idea… I guess putting a small hole in the rain skirt so it overlapped the tarp would be ok since you could get away with putting quite a bit less stress on the rain skirt than you would need on the tarp. I figure by putting something over the tip of the trekking pole would be a better idea as it could completely cover the hole and the trekking pole, which water will likely end up running down…

"Furthermore, I plan to not raise the front end as much as in your set-up, so the bottom part of the skirt will be lower, thus avoiding the need (????) of the umbrella there."

I have found that with the 6.5 wide tarp that I have, the height that I have it is about perfect. Much/any lower and the walls would not be steep enough to get under it towards the back without the walls hitting me, although, with the other pullout on the back, it does help. Getting the back wall steep enough to use is important when using tarps in this pitch.

Stick, to avoid damage when tightening the tarp (and skirt), I plan on reinforcing the CF (at least three layers) before making the holes. I also want these holes to be very tight around the tips (therefore I’d make these a little smaller than the OD of the tips, but yes, I can visualize the risk of water seeping through the hole. Thanks for pointing out.

With regards to lowering the height of the tarp…… this doesn’t have to mean that the angle will vary. Obviously, at the same width of the tarp, reducing the length of the pole will make the back wall less steep but…… IF we reduce the width of the tarp, this doesn’t have to be the case. Let’s suppose the back wall of your 6.5’ wide tarp has an angle of 45º (in relation to the floor); according to the little drawing I made, the height of your tarp will be 4.6’ (and the floor width will be the same). Reducing the width of the tarp to 4.5’ (whilst keeping the same 45º angle) will automatically reduce the height to 3.18’, as well as the floor width (which, obviously, is quite narrow). Because of the narrow floor space it becomes very important to have at least two tie-outs at the back wall to avoid touching same.

I will be interested to hear how this turns out for you. I still have doubts about making a hole in the tarp… I feel like the stress alone will immediately begin to stress, and stretch, the hole, even when being reinforced with extra layers of cf. Maybe a grommet would help a bit more here, along with the few extra layers for reinforcement?

As for the height, I agree that you would not need (or even could) get your narrower tarp as tall as my tarp at 6.5' wide, but you see what I meant by the angle of the back wall. With narrower tarps, it is a bit easier to get enough steepness in the back wall, than it is with wider tarps simply because it doesn't need to be so tall. With mine, my GG LT4 pole is fully extended to get the right amount of height I need for the back wall to be steep enough to actually use. Also, as I mentioned, having a tie out on the outside back wall to help pull the tarp pout is also helpful, even on smaller tarps like the one you want to make.

What type of groundsheet are you planning on using? If you have a center tie out on one of the sides, you could attach that to the supporting pole with some shock cord. Then, if you are using the rain kilt as a beak, you could slide the ground sheet up the pole, thus decreasing the gap between beak and groundsheet. I've done this with a zpacks groundsheet and it worked pretty well against any splash. I don't have a rain kilt but I think using it as a beak is a great idea.

I carry a cuben tarp in similar dimensions as you are planning. I usually sleep cowboy so the tarp is only for a just in case surprise storm. I've had it out a couple times in "calm" steady rain and light snow and it has worked fine for me. If I lived somewhere with a lot more precipitation, I would carry a larger tarp. Personally I feel a 6'x9' would be fine for solo. The reason I can get by with such a small tarp is that I'm in the arid southwest and rarely encounter rain.

Stick: > I feel like the stress alone will immediately begin to stress < I’ve been thinking about this as well and, if several layers wouldn’t work out, it would be easy to add, instead of a grommet, a small piece of hard plastic, encapsulated in -and sewn to- a layer of CF (on both sides of the plastic). If experience tells this would be necessary, this mod (the plastic sewn to both layers of CF and bonded to the CF on the inside of the tarp) would be easy to add.

> With narrower tarps, it is a bit easier to get enough steepness in the back wall < That’s what I thought and that’s why I am tempted to not increase the regular width of the CF (using my skirt for the extra protection).

Chad: Good idea about using the groundsheet to tie this to the pole, providing extra splash protection. My current groundsheet is “bathtub-style” with built-in poles on the 4 corners and guylines to keep the walls up, but….. I made it many years ago and it’s pretty heavy (215gr ≈ 7.5oz), so after the tarp I want to make a new groundsheet based on the same principle using Cuben Fiber (CT3.5K.08). It would be easy to make one wall a little higher with a tie-out in the centre to be able to tie it to the pole.

Even though I live in Southern Spain, where -like in your area- it doesn’t rain much, on my long-distance hiking I go north and have encountered all kinds of weather imaginable, so my tarp MUST be able to withstand this. I totally agree with you on cowboy camping and only use my shelter when I think weather will turn bad. That said, I always use the bathtub groundsheet (although, when weather is good, I don’t tie the corner poles).

Another mod (on the groundsheet) that I’ve been thinking about is adding a mesh “roof” to get bug-protection – but I have to think a bit more about this (don’t know whether it’s a good idea).