Thanks to those who have replied so far. Chief, your comment about rotating knife is particularly pertinent, as yes, this is something I do a lot when clearing track in Jungle. I know a machete or Cane knife would be "better" but if travelling by Sea Kayak, not really practical. A lot of thinner scrub responds to cutting more efficiently by using a upswing as gravity pushes stalk down against blade. The downside (!) is that it is very easy to rotate blade and slash Achilles tendon if not concentrating. Haven't done it, but am always aware of consequences of doing this in isolated area days away from help.