I have a Speedtech (the one that doesn't care which way you point it -- rather expensive) and that is the one Mary is complaining about.
She and I were getting blown off our dock trying to stand there and the best it read was 15 knots.
I sort of believed it. Until the next day I drove down the road at 50 mph and held it out the window -- still 15 knots.

On the other hand at this past Wave Nationals it was howling and it was reading over 20. Must have fixed itself.
Rick