New GPS. How to find Speed?

[RonandReel]

Got a new GPS. It reads 38mph. and the speedometer reads 30mph which is the correct speed? How do you find the right speed? Thanks for any help.

[GPS]

Believe in your GPS. Your boat speeddo is most likely inaccurate since it operates on water pressure in a little pitot (sp?) tube.

[REW]

i agree, the GPS should be correct.
If you have a portable unit - put the gps in your car and drive down the freeway at 60mph.
In general you car's speedometer is generally quite accurate.
See the relationship between your car speedo, and you gps.

finally, if driving 60 mph - it is very easy to verify the calibration of both car and gps by using a stop watch to mark off 60 seconds to the mile markers on the freeway. If you hold the constant 60 mph speed - you should be able to pass mile markers at exactly 1 evary 60 seconds. Or a mile per minute.

Take care
REW

[gps]

make sure it is set for mph and not knots. You can find what it is set on in your set up pages

[RonandReel]

Thanks for the help. I will be going to Alex. Min. this weekend. will have to try to set the speed.