In reply to Andy Say:
There's more than 1 way to skin a cat. There's other ways, some better, some worse. But if that's all you have, then you can only pish with the cock you've got.
I have used them numerous times, albeit short distances over varied terrain, and unless it's made correctly, can be a bit of a cake and arse party. But it gets the job done.
It takes some skill to make it, with practise. If you have just thrown it together following a picture, never done it before, then it's not going to be perfect.
No harm in knowing it/practising it. It's another string to your bow.