I've been considering whether or not to go for a single skin shelter but it seems that I've ended up with more questions than answers. The primary reason for going 'single skin' would be to reduce weight and there are various options but generally speaking they fall into 2 categories, tarps or tarp tents, again there are 2 main types of tarp tent, those like the Henry Shires 'Tarptent' single skin range with sewn-in mosquito net and those that require the use of a separate net.
What I've found is that if you look solely at weight by the time you add a separate net to a single skin tent you can end up with something heavier than a lightweight double skin tent which rather defeats the object in my case. That said you seem to get more space for a given weight using a single skin/bug net combination.
With that in mind I'm drawn to something from Henry Shires, the Contrail, Rainbow or Moment to be exact. The Contrail is the lightest at 696g followed by the Moment at 810g and the Rainbow at 965g. I like the weight and width of the Contrail but it looks susceptible to side winds and also looks like it could flatten at the tail, the Rainbow is also likely to be effected by side winds but I like the layout although it's about 25% heavier while the Moment looks like it would be the least effected by changes in wind direction, isn't much heavier than the Contrail but looks a bit narrow at the head and foot.
Of course there's always the question of the Scarp 1, would it be better to just use it at 1250g and have an all season fully featured double skin tent? It would seem so as my base weight for tomorrow night is currently sitting at just under 5550g, about 1300g of which is my Phreeranger set-up as a single skin, if I used a Contrail it would be about 4950g but using the Scarp 1 would mean I didn't need to take a bivvy bag at 305g which would leave me with a base weight of approx 5200g with the benefit of a double skin tent. To really benefit from a single skin I'd need a lighter bivvy bag, e.g the Titanium Goat Ptarmigan at 193g which with a Contrail would give me a base weight of about 4833g.
In the end it's just under 400g difference between a Contrail based set-up and a Scarp 1 set-up and that makes for a very convincing argument in favour of the Scarp 1 if my primary reason for considering a single skin is weight. As it is there are 3 areas where I can save weight, Shelter, Bivvy Bag and Rucksack, I'm interested in the ULA Ohm which would save me over 400g on my current pack, the Haglofs LIM 45. That may well be my next purchase, I like the style of the Ohm and if my calculations are correct it's a little smaller than the LIM 45 which would be perfect as I can almost get my gear into a Karrimor Hot Rock 30
As I said at the outset, after considering the options I'm left with more questions than answers although tomorrow night may help fill in the gaps (if the weather forecast is correct) as far as single skin shelters are concerned. It hasn't been a complete waste of time though as I'm pretty certain I know what my next pack will be.