Thanks
Thanks both for the reply and answer.
HD - yes I take your point about higher speeds, workloads and traffic separate service. Yes you are correct that marine traffic is generally uncontrolled and is unlike aviation in that respect, and probably with higher margins for error, so the skipper is exclusively responsible for his own navigation save for within a VTS area where a traffic separation service is provided, or similar controlled port where shorebased stations can issue windspeeds & directions for arrival and in limited circumstances issue clearances in tightly defined sea areas or when vessels pass a mandatory reporting point.
And 500' thanks for posting those links - it reads very much like ADS-B does fulfill much the same function as AIS - I was aware of FlightRadar but was unsure on what technology it was based, so thank-you.
Don't think my little put-put training plane will ever get it though!
thanks