Home › Forum › Ask A Member › Speaking of "Need for Speed" How to MEASURE speed? › Re: Speaking of "Need for Speed" How to MEASURE speed?
If you accurately calibrate the water pressure pitot type speedos against a standard like a dead weight test they are accurate. The water pickup must be in the free stream with no air being picked up. Keller pitot speedos are good units used on race rigs especially since you could easily observe the speed changes in turns and accelerating. I do speed checks over a distance and time that is how GPS does it but they also have their accuracy issues with satellite signals. GPS units are certainly the most convenient to use. If you are traveling on water GPS measures speed relative to fixed earth regardless of currents, water pressure pitot measures relative to the water with currents accounted for.