Why Bivibags and tarps?
it reminds me of 2 occasions that might go some way to explain why both is a good idea:
1: on a British Army TA exercise the whole platoon had made a Base camp known as a "harbour" with around 30 men paired up in "shell-scrapes" (holes about the dimensions of a flat poncho and 2ft deep) the base looks a sort of triangle spider web from above.oh and...it was a wet exercise.
Constant heavy rain, every shell-scrape had a 58" poncho or self bought tarp(if you could get hold of one) as a roof.
nearly everyone was using the issue 58" sleeping bag a down bag with a waterproof base (4 seasons when dry, 0 when wet!).
I used a cheap Goretex copy (Hydroram) and by the end of the day my sleeping bag was one of the only ones that was dry, and not covered in mud!
Everyone was trying to beg or borrow the last 3 or 4 dry sleeping bags!
so in that situation every person had a tarp(of sorts) but the sleeping bags all got wet!
I remember a previous exercise again the "shell-scrapes" and again poncho roofs, exept that time i didn't have a bivibag and water ran down the shell-scrape side, into my sleeping bag, the waterproof base had limited use as i could feel the cold water running down the base....yeah...nasty!
after several attempts in the early hours to move onto the dry part or keep warm I gave up, got up put my Issue PVC waterproofs and got bag into the sleeping bag! uuugh!
the down side...to down!
ugh, a pun, I didn't mean to!
apparently some Army exercises in the past had been called off in the past, due to wet 58" sleeping bags!
2. on a Civilian Mountain leadership course, we all bivied overnight on the side of a Welsh mountain (Cadair Idris).
it was wet that sort of "fine misty rain" that soaks everything, this time most people used bivibags, some were military.
nearly everyone including myself got soaked, due to the small gap you leave to breath through.
out of 20 people 3 people stayed totally dry, they used sleeping bags under a tarp. they'd built a sort of "C" shaped wall from rocks and placed the tarp over it.
to be fair using both Bivi bag
and tarp is a "belt and Braces" approach, but even the military use both as you can hold a meeting read maps etc in Bivibags!
I tend to use both.
The IPK sheet
uuuugh... Everyone seems to think the IPK sheet is amazing....it isn't! it's just cheap!
An IPK is an Individual Protection Kit. A bit of Army surplus. You get a plastic pouch with a plastic OG waterproof sheet. A selection of Aluminium pegs and a decent length of white nylon cord.
They were designed to be used to provide overhead cover to trenches / foxholes to protect against indirect fire and NBC agents. The idea being you dug the trench made a supporting lattice from the white cord and pegs placed the sheet on top and then covered that with the spoil dug from the trench. Fine in theory... Possibly not so in practice.
Bushcrafters like them because you get a sort of useful: waterproof sheet, pegs and cord for a extremely cheap price... Therefore ticking some of the Bushcraft mental check boxes.
Army Surplus. Check.
Low Cost. Check.
HTH
John
I totally agree with
Johnboy
It is....
a sort of usefulwaterproof sheet
that's the
best description I've seen!
Can I add...
IPK sheets are OK for a short term solution because that's what they are designed for, to be buried, provide some basic protection and then it's forgotten!
I've had bad experiences with IPK sheets!
They aren't laterally very strong, (if torn will rip)and it's difficult to add suitable hanging points without weakening it further.
I've tried glue, Duct/Duck tape, rivets, sewing, Big brass Grommets, all of which failed, I also tried joining 3 together, which just made the strength problem worse. I'm yet to be convinced you can make a re usable shelter from it!
not as strong as a "basha" or "poncho" by a long way.
also I bought one that was sealed but every fold you could see light through so barely waterproof!
ground sheet? check.
shelter?...if you're careful, but you'll need to make sure you can tie cords somehow.
windy stormy weather?...forget it!
WARNING, as the saying goes
"you get what you pay for",
don't expect big things from something that costs £5!
don't believe the advertising hype...if you only have £5 to spend, by a builders tarpaulin, string, and a few 6" nails....hey presto a much better shelter!
or save towards a 2nd hand poncho!
The pegs and cord are worth it!
best for making an underground shelter with.....it even comes with instructions how to!