Bluetooth Sonar Fish Finder for Smartphones

Idea is right, but implementation ... questioned.
Without 3D (and GPS) the picture is not that useful for a fisherman.
You must see the fishes against your position, not the sonar.
And claimed 50 m (150') distance for Bluetooth is out of typical Class 2 specs: 10m (30').

Shouldn't a problem if SW would take in account two positions: the sonar and your.