Originally Posted by lightning
I need a GPS speedometer that is self-contained (internal batteries) and preferably no more than £100
Garmin 176, garmin gps ii, gps iii, gps v, Garmin Emap, Etrex legend, Magellan 310, 315, 320.
Just a few off the top of my head that give good speed readouts in nautical measurements.
The Garmin Quest was designed as a motorcycle unit, colour, waterproof and reads in nautical. It can also read bluechart cartography.
All of them available off Ebay for less than £40.
For a bit more, the garmin 60c is a good unit.