Saturday, 5 September 2009

Single or Double?

As I mentioned I've been trying my Phreeranger as a single skinned tarp tent, in fact I slept in it again last night and to be honest I'm wondering if I really need a double skinned tent. There was some condensation on the inside of the fly this morning but again no drips. I was using a bivvy bag anyway so a few drips or moisture knocked off due to heavy rain/wind wouldn't have been a problem. There are advantages to using a double skin tent though, the oft quoted one is that they reduce condensation but I'm not convinced that this is the case as I've often found the inside of the fly to be wet when using a tent, what the double skin provides though is a barrier between yourself and the fly but with the Phreeranger and most Tarp Tents there's so much space that there's little chance of touching the fly anway. The other 2 advantages of an inner are heat/draft reduction and bug proofing, the fist may not be too important if you're using a bivvy bag as it protects from drafts and should upgrade the performance of the sleeping bag, I would however prefer to have some protection from insects and I don't believe a bivvy bag even if it has a bug net offers quite the same protection/ease of use.

I've been looking at some of Henry Shires 'Tarptents' and they solve the bug issue by having sewn in netting and groundsheet. The only issue remaining is loss of heat but I wonder if the bivvy bag overcomes this. My bivvy bag is an old heavy Goretex one weighing in at 596g which is heavier than my inner tent but I don't think I need the level of protection that my bag provides so something smaller and lighter would be fine assuming it was breathable enough, perhaps even something like the PHD Drishell cover which only weighs 163g. If using a bivvy bag allowed me to use a sleeping bag with a lower rating then some of the weight of the bivvy bag is offset against the weight saved by using a lighter sleeping bag.

I like the idea of the 'Tarptent' Rainbow/Double Rainbow, the Rainbow including poles/groundsheet/bug net and 6 pegs weighs 965g, add the PHD sleeping bag cover for a total weight of 1128g, the larger Double Rainbow weighs 1135g, or 1298g including the bag cover but offers a massive amount of space, 2250mm L x 1220mm w x 1100mm H with 600mm wide (at the apex) porches on both sides.

I can't see any other disadvantages but if anyone can think of something that I've overlooked please add your comments.


  1. Hi Richard,
    I use silnylon groundsheets, and i haven't had a problem. I often use a polycro/window film footprint with them. I think that helps to prevent condensation from the ground, that some folk possibly mistake for a leaking groundsheet, as well as keeping it clean.

    Double skin tents have just the same amount of condensation as single skins. The only difference is the inner tent seperates you from it. With a single skin tent, i feel you need plenty of room so you don't touch the walls. I've used a couple without having any major problems. In fact, i've often been drier on multi-day trips, as there is no soggy inner to try and dry out for the next nights pitch.

    I've been using a TitaniumGoat bivvy bag with single skin tents, to protect my bag from any moisture from the ground or tent walls. It has a silnylon groundsheet and a water-resistant upper, and weighs just under 200g. Since i started using a quilt with an Epic shell, i leave the bivvy-bag behind in warmer weather.

    I think i've finally found my perfect shelter though. The single skin MLD Duomid has plenty of room to avoid touching the walls. I use the MLD Inner tent during midgie season, or a bivvy-bag outwith it.

    One thing i like/want/need is a bathtub floor, even if i'm using a bivvy with a waterproof floor. I like to have a dry area around me. If the shelter doesn't have one, then i like to fashion one of my own using polycro/window film. I'll use twigs or stones around the edges of the sheet.

    TarpTent make some fine shelters, and the workmanship is top quality. I don't know how the Rainbow performs in strong winds though.

    Mike fae Dundee

  2. Hi Mike, thanks for the information, it's always good to hear from experienced users. I agree about trying to dry soggy inners. I've never had a problem if the fly/inner can be separated but if they can't then it can be a problem. I like to use a footprint for a variety of reason not least because it keeps the groundsheet clean which in turn keeps the inner tent clean. I like to pack my tent in the rucksack but the footprint can go in a pocket. I like silnylon as a footprint as it takes up very little space although it's heavier than polycro.

    I think the Rainbow should be pretty stable, it looks like the Double at least can take 2 trekking poles to help in high winds but as it's essentially the same the Phreeranger it should cope well enough.

    I looked briefly at the MLD Duomid but I think I'd prefer a sewn-in bug net for the little extra weight that it brings, that said it's definately spacious and looks like it would take a bit of rough weather.

    I'll have a look at the Titanium Goat bivvy bag, sounds like it would do the job.

  3. I have the TiGoat bivvy with the part net hood. If i was to buy one again, i would go for the full net hood. It can get a bit hot in mine on warm, midgie nights, and using the full net hood opened should be cooler.

    Mike fae Dundee.

  4. I've just been checking it out and figured I'd go for the full mesh myself as it only adds 30g. I didn't order but that looks like the one I'll go for when the time comes.

  5. Interesting experiment. Your bivvy bag caught my eye. Looks like a vintage goretex. Is it by any chance a Pheonix bag?

  6. Hi Dave, the bivvy bag was bought from Field & Trek 18 years ago and listed as an F&T Freedom Bivi, the label inside says 'Mountain Range' made in Cumbria. Shouls have bought a Phoenix Phrontline with the diagonal zip ;-)

  7. The material looks very familiar to me. I retired my Pheonix bag in 2007 after 19 years of faithfull service. Couldn't bring myself to bin it though.

  8. It's like a soft open mesh on the inside, presumably to help absorb moisture. Did you see the date on the invoice, whats the odds of that happening.

  9. Penny, my partner, prefers using a single tarp tent because of the air flow. She claims that she can breathe better and as a result sleeps better. Even a full mesh inner in the summer can make for a stuffy nights sleep even with the inner door open.

  10. Hi Mac interesting discussion and choice of shelter you are mulling over there. Inner tents protect us and our sleeping bag from condensation and add warmth, which can actually help reduce the effect of condensation.

    I measured while wildcamping with Alan Sloman a big difference in temperature from the inner to porch and then outside of the tent. I would say an inner tent is like wearing a light fleece in the warmth it offers. In some ways the weight saving of not having one is debatable.

    I have had tents shake in storms and any condensation on the inner sprays over the inner tent and kit stored in it. Without an inner tent it would need a bivvy bag to keep of the damp on a sleeping bag. Those who say it is not an issue need to spend a few stormy nights in the Highlands having their shelter bashed about.

    If you are going to get a Rainbow the managing of condensation is the key point - as the dew point on a single wall tent is reached faster than a double wall tent and hence condensation is more prone in those types of shelters. Where you pitch (like not low in a valley on wet ground with no air flow) is essential. The pyramid style of tent have a chimney effect as they have big vents at the top and reduce moisture in side them and as Mike says keep damp sidewalls well away from you.
    Henry puts a lot of air flow into his designs and hence in strong winds it will feel cold. I find that with the Scarp which is a double walled tent, and zip up the inner fully to keep warmer. John Manning mentioned his cold time with his Tarp Tent on the Challenge in the TGO this month. One other link to look at is this about the tent. You need to ask for more guyline attachments and pitch it in sheltered spots.

  11. Martin, useful information there. You're quite right in what you say about the benefits of an inner, more heat, separation from the condensation present on the fly, less drafts but I wonder how much of that can be covered by using a bivvy bag? Ideally I'd like to have the option of an R/DR with an inner tent, the best I'm likely to get is if I make a light inner to attach under and inside the mesh. The R does now come with attachments for trekking poles to stabilise the tent in high winds but as mentioned in the discussion linked to (thanks for that, plenty of food for thought)extra guylines are desirable/essential.

    To be honest the Scarp 1 looks a better bet, unfortunately I don't really like transverse single pole designs or fixed end struts, especially the end struts as it makes the packed length quite long. As you know I simply couldn't get on with the Laser even though it's an extremely well liked and capable tent.

    I'm on the horns of a dilema, my heart says the R/DR, my head says wait.

  12. Mac: Yes I'd caught sight of the receipt. Scary! Not least of all because the intervening 18 years have gone by so quickly and my garage (yoúrs too I guess) has becoem so full of gear.

    Interestingly I think this ties in nicely to Hendriks piece on green gear. Impressive that you are still getting use out of the bag after so long.On the other hand, even though my similarly aged bag is retired I can't bring myself to put it in the (recycle) bin. How do you set aside a friend of 20 years?

  13. Too True, time flies like an arrow, fruit flies like a banana ;-)

    Would you believe that my bivvy bag hadn't been used until last week, I carried it in my pack in winter as a safety measure and fortunately never needed it.

    I know what you mean about throwing away an old friend, I could have traded my old Wild Country Quasar against a new one last year but couldn't bring myself to do it. Too many memories of a more carefree time in the old one.