I'm no rocket scientist... but isn't this a bad idea if you ride on rivers? What we care about is relative boat speed (i.e. boat vs. water, not boat vs. land). If the river is flowing at 5 mph, and you are driving up river, holding position, you land speed is 0 and your boat speed (pito tube or paddle wheel sensed) is 5 mph...
I guess we will all riding at 19 mph up river and 29 down... ?