It's a Garmin. When putting in the alarm distance the only choice is in 100ths of a mile. I put it on 1, if the alarm goes off I extend it to 2 or 3 100ths. For navigation the CP is set on nautical miles so I guess it would be 100ths based on nautical miles. The distance difference as a guess can't be more than 10 to 20 feet.

Good call.

It can get confusing as there are times when I do change the CP to statute but that's mostly on the ICW,,,,,, hmmmm?? They don't call it that anymore do they.