[GPSNavX]

A quick read of Interphase Scan 180 manual shows it does support NMEA data depth out ($__DBT). NMEA data depth only provides for a single digital depth reading. MacENC/GPSNavX can display that depth reading in the instruments panel.

In order to get the actual sonar scan in a window on your Macs display would be to use a video to digital converter such as Elgato Systems EyeTV Hybrid..

http://www.elgato.com/index.php?file=pro...yetvhybrid

I have an EyeTV for my iMac and it works great with all sorts of video sources plus it includes a TV tuner. Plugs right into the USB port. You could even make recordings.