"...Even a receiver only I think is essential--in fact it doesn't even have to be interphased with the chart plotter (better if it is). I think we will see NMEA 2000 plug and play AIS units within the year and that the price will become affordable... Reply: I agree with Bob and others about how affordable AIS receiver-only systems already are. Subscribers to T&T will note that I just bought a bundle with some Navigation software that included a one channel AIS receiver for less than $200. The AIS is only one of the Class B listeners that can receive one channel at a time but is designed to scan both AIS channels and automatically use the channel with the best signal. I figured for the price of one nights transient dockage, I can always replace it in a few years when the AIS Transmitters come way down in price. Here's the site I used (there are others) and I have no connections other than a customer: http://store.milltechmarine.com/smrasraisre.html Tom Lawler Emily Grace