Westerly, et. al...
It is confusing, isn't it? Lots of opinions, some from "experts", which seem to conflict with one another.
A few notes.
1. There are TONS of posts on these issues on the SSCA Board and on Cruisers Forum, among others.
2. I have done a lot of these on the subject of RF grounds, antennas, appropriate radios, licensing, etc., etc. (I do this for a living these days). In particular, you may want to see my posts on "RF Grounds in the Marine Environment" and on inexpensive ham radio setups.
3. Just a word of caution: be very wary of anyone who tells you the very tired stuff about "100sq feet of copper", or that you need external ground plates. It just ain't so. There are lots of ways to fashion an effective RF ground system; some are referred to in the post noted above.
4. There's LOTS of activity on both the ham and the marine SSB nets. I participate every morning on the Waterway Net on 7268LSB at 0745. This net provides offshore weather and other services for boats from NovaScotia to the Caribbean, and it's been on the air every day for forty years or so. See the website: Waterway Net Web Site
The MM net on 14300USB is active much of the day. The Cruisheimers Net on 8152USB (marine SSB) begins at 0830 EDT every day. There are many others. The lists on Gary Jensen's website is very good: Pactor-II/III Radio Modem sales/support, FCC License filing, Marine SSB & HAM Radio Net schedules/frequencies.
5. IMHO, it's well worth it to get your ham ticket, since it opens a world of fun and utility, not just when afloat but wherever you are. There are over a million hams worldwide, so there's always someone to talk to. English is the lingua franca in ham radio, though you'll sometimes hear other languages. As was suggested, 20 meters is the workhorse band for long-distance communications, year in and year out. If you take some pains with your installation and if you practice your radio skills a bit, you'll be able to reach out and touch someone a long ways away with regularity, even when propagation sucks.