speedometer vs. GPS

[chipj29]

Originally Posted by Acres per Second

The statement ignorance of the law is no excuse is centuries old:


http://www.rbs2.com/cc.htm

The same source continues:

Please explain how someone on a boat is supposed to know exactly how fast they are traveling if their boat does not have a speedometer? There is no law that requires a boat be equipped with a speedometer. That would be my challenge to a judge if I were to get a ticket.

I am not being ignorant of the law, as I am perfectly aware that there is a speed limit. Without a speedometer, I might be ignorant of my exact speed however.