What do they check for when pulled over by the MP

[Broken Glass]

If you run your boat at idle,(or any other set RPM) through the channel, in both directions, with your GPS functioning properly,then add the two speeds together and divide by two, you will have your hull speed over ground without any current. Subtract your calculated hull ground speed at set RPM, from your speed running with the current, and you will have the speed of the current in the channel. I have done this a few times and the speed varies within the chanel. It is determined by not only the width of the channel, by by the depth of the water.