I really don't know how to answer your question. Here are some thoughts:
1) Typical normal accuracy (one-sigma) for well-designed civil GPS equipment under nominal operating conditions with SA off should be about 10 m horizontal and 13 m vertical. Think about this for a second. Although for positioning this is incredibly accurate, for speed measurements it could give some strange results, especially if conditions are not nominal and you get multipath effects and ionosphere effects, which are all too common. BTW, I also read that in a moving vehicle GPSs are more accurate. Not sure why this is the case.
2) But here is a much more compelling argument for me. With WC racers being on the edge of disaster at speeds of 100-130 km/hr in SG and DH events (and skis of 200+ cm), it is hard to understand how you or Ghost can manage such speeds with short, shaped skis with 13.5 m radius. I simply cannot imagine how you keep such a ski flat, in a straight line at near 130 km/hr. Just does not make sense to me. Maybe I am dead wrong (won't be the first time).
I don't know how Newfydog does it, but on my 13-m radius Fischer WC SCs, I alternate from edge to edge. They are fine if the snow is hard or at least not much more than a few inches on top of the hardpack. I have noticed though that if there is a significant amount of denser snow turning anything more than a slight amount can be very tricky; the ski will want to turn more than you can turn at that speed. It's ok on hardpack, even skimming over small bumps (say 6 to 8 inches), as the grip won't be there, but if the snow is grippy, you can hook a tip and that isn't good.
Quick question for you Tom, have you ever straight-lined Little Devil or Spectacular at Blue Mountain Collingwood? If so, on what skis, what snow condition and how fast do you think you were going? (and how much air did you catch off the flat section before the second steep? edit: for those who don't know, there is a little hill at the top then flat where you decide to go to Little Devil or straight on to Spectacular, then it's steep, then not so steep, then steep again and eventually tapers off at the lift, nowhere is it really steep though)
Edited by Ghost - Tue, 03 Feb 09 01:48:26 GMT