Speed measurements with a Garmin GPS-12

**
One of the more frivolous uses of a GPS reciever is to measure personal speed records,
which I have done for various sports listed below.
Estimating accuracy is tricky, because most of the errors in the GPS position
measurement vary slowly with time and so cancel out in speed calculations.
Perhaps the best measure is the velocity indicated at rest, which is usually less
than 2kph. Positions are measured once per second, and the maximum speed indicated is
the average over this time, which means that lurching forward could give a misleading
velocity for that interval. Averaging over 3 seconds is a better indication
of true top speed, but I've only been able to do that for those runs where I have
access to the tracking log. The third column is the peak speed translated to mph.
**

**
Mark Harris 21-Feb-2000
**

**
**

**
**

Sport | Peak speed |
3-sec average |
Peak mph |

Slalom skis | 123 kph | 115 kph | 76 mph |

Telemark skis | 71 kph | 67 kph | 44 mph |

Sea kayak (surfing) | 21 kph | 13 mph | |

Windsurfing | 41 kph | 35 kph | 25 mph |

Skate sailing | 42 kph | 25 mph | |

Kite skiing | 38 kph | 23 mph | |

Kite skating | 40 kph | 24 mph | |

Ice yacht | 38 kph | 23 mph | |

Ice surfing | 26 kph | 15 mph |