Hawkram said:
Thank you to everyone who offered information.
I've just been given a new sleeping bag that has a central zip, it makes life a lot easier getting in and out of it.
A bivvy bag that also had a centre zip would be ideal.
Is there anything like that on the market?
Cheers
Mountain Range make some very good bivi bags. I have both the double-hooped model and the diagonal zip model. They are not cheap though. That said I've had the double-hooped one for 12 years and it is still going strong. The zip on the diagonal is covered with a velcro baffle. I've never had problems with water coming in the zip. You can sleep in it zipped up completely and the only moisture problem is condensation from your breathing. I find it better to keep it a bit open, with at least a small breathing hole, if not my face entirely exposed unless it is absolutely pi**ing it down.
As you say, the diagonal zip facilitates much easier entrance/exit from a top-zip bag, which is particularly useful in very cold places - you can get dressed in stages while still in the bag. Yes, with a top-entrance bag like the MOD one, you don't have the zip as a potential entrance for water but you do have the blooming great hole at the top! Also, the diagonal zip means you can store your clothes, headtorch, etc at the top of the bag above your head. The zipped design makes it more expensive to produce though.
Also worth a mention is that a friend of mine was recently telling me his experience with the army bag was not good - he was getting a lot of condensation inside the bag that was dampening his sleeping bag. I know other people have had good experience of the MOD bag and don't seem to have a problem. But this particular one didn't seem to be very breathable.
I bought my diagonal zip bag from Penrith Survival a few years back and it wasn't quite as pricey as they are now but was still considerably more than an MOD bag. Still available at:
http://www.edirectory.co.uk/penrith...a.asp?pe=BCJGDECQ_BB+Diagonal+Bivi&cid=55