We’ve been competing in mountain marathons for 18 years. We are not exactly lightweight fanatics but know we can go quite a bit faster with smaller lighter sacks. Everyone has a target weight they like to achieve for the equipment they carry… for us a combined sack weight of 9 kg is an absolute maximum. However, around 5 years ago I felt I’d spent enough years shivering the night away on bubble wrap and in a minimalist sleeping bag. Getting old I guess. Something had to be done.
I remember in particular often feeling cold from the ground and having to turn over to warm the bits that were in contact with it.
We experimented with aluminised mylar (space blankets) that can be heat bonded to form air pockets. It worked well but the main drawbacks were:
- Leaking around the valves
- Inter-linked air pockets are generally not a good idea as in the event of a single puncture all your air is lost and the mattress becomes useless.
- Mylar is not elastic and when you stand on part of the air envelope the redistributed air causes a rupture in another part.
We have also experimented with 'lay-flat' poly tubing. However, the inherant lack of elasticity in polythene resulted in a lot of envelope failures.
What we particularly needed was an elastic membrane that when the user stands on or sits on one part of the envelope, the redistributed air was accommodated in another part of the envelope by it’s elasticity. We also needed several air envelopes so that if one envelope failed it could be easily replaced. The air envelopes also needed to be quite easy to inflate and seal and be relatively cheap and easy to source. They also needed to be light.
Now then, what can you think of that has all these qualities? Balloons of course: cheap, elastic, easily sourced, easy to inflate and seal. Perfect. Nearly.
Balloons? Are you serious?
Are they strong enough to hold a persons weight I hear you ask. Well yes they are, especially if the weight is distributed over several of them. They can take a lot of abuse too – you can jump up and down on one end and the other just inflates with the extra air.
However, what balloons don’t like is:
- A single sharp point of contact – a pin or thorn or such like.
- Static discharges – the heat generated in a small static spark is enough to initiate a rupture.
If you want to know more about balloon failure go to our Further Advice page under the Information tab.