Thinking about Johns questions, a few weeks ago I was traveling with another skipper who had invested in Furuno's fantastic AIS system, but had passed on adding the ARPA card to his chartplotter/radar. While I'm a fan of AIS I think an ARPA feature is much more valuable and would be the first thing I'd buy (or recommend). I have used ARPA hundreds of times and the Furuno implementation is fantastic. I was really surprised how good it was compared to the Nobeltec solution I had on my Camano. The nobeltec software seemed to be running the course analysis algorithm too fast, resulting in wildly changing course vectors. It may also have been that they didn't average the selected target very well, accounting for the wild course output. Anyway the point is while AIS is great, I think ARPA is a requirement for passagemaking, while AIS is a "really nice to have". Scott Bulger, Alanui, N40II, Seattle WA