Hello, Mr Rawles,
I´m writing to you in response to Mike B´s letter “My Experiment with a Field Gear Invention.”
Halfway´ through the second paragraph I began to smile since I instantly recognized the item he was writing about. How different outdoor culture can be from country to country. In Sweden this is called “sittunderlägg” and is somewhat of an household item among outdoors people. However, I would like to add some tips about the manufacture of the same. In Sweden they are made of closed foam, the same material as in the cheap camping mattresses. This has several advantages. First it´s cheap. A car mat can supply material for maybe one or two but a six foot mattress can be cut up to comfortably sit five or six people. Seeing both can be had for ten dollars or less the camping mattress saves some money, Secondly, weight. This I have not tested but I can´t imagine that car mats are lighter per square inch. Third and most importantly, closed foam insulates from cold. A car mat seat may be all right during summer treks but if you have to bug out in low or even sub-zero temperatures you would want to sit down without losing precious body heat.
As always, thanks for a great blog! – D. from Sweden (Editor of Att Leva Efter 2012)
The “Posterior Flap” described by Mike is popular among skiers, who use it to stay dry and warm while sitting on the ski lift. I believe some ski pants have the flap built in. There are also commercial “belt mounted” flaps available; so it may not be necessary to build your own unless you have unique requirements: