In reply to Tamati:
I've washed mine about 4 times in 5 years: Once due to a rotting sheep, twice due to guano and once when it had so much ingrained dirt in that you could hold a 4ft length of it vertically
In reply to Tamati: I tend to throw mine in the bath and waggle it about in warm water, but only after sea cliff climbing.
If it's realy dirty neat detol cleans it good(joke).