I believe Humminbird also has a heading sensor gps puck that is an add-on accessory. It matters when you get to below .5mph or so. Anything faster and the gps will usually show boat travel direction. .5 mph and slower and you just get a red circle indicating your location on a map, not your direction of travel. Very frustrating when you are trying to sneak up on a fish crib and you lose direction of travel.

As for gps puck location. While I agree placing the puck over the transducer could be considered pointless considering the error built into civilian gps. I still like the idea of reducing error every chance I can cost justify.