Which GPS unit should I get?

[Steven Vaccaro]

i have the same (keith bradley)
checked it with my car ;seemed ok
giving constant readings in my boats so ok for me
one thing perhaps : it's a 1hz measurement

this means that it only measures one time every second
so you will need a rather long straight line for a reliable measurement ( depends on the speed your boat is doing)

more expensive devices measure a couple times/second ( higher hertz) so they don't need such long constant straights

thanks for the info! that was probably my issue.