I'm not familiar with the H/B 581, so I can't give you a definite answer. I can tell you this. I had a Garmin combo unit and I was able to use the bare wire Humminbird cable to connect my 778 Humminbird to my Garmin. What you will get is position and speed. It will not share any maps. I think the screen will show your waypoints and tracks, but no shore line etc.