I'm mostly interested in the "dreaming" kind of planning. ... I'll have to see about installing Google Earth on my computer... I run Linux, and last I checked (over a year ago), they didn't have a Linux version, but maybe they do now.
Google Earth will not get you anything special, and anyway it's a browser plugin nowadays. Google Maps and Geogarage both work fine for me on Firefox on Linux, and they'll do exactly what you want.
Believe me, I spend lots of time that should be spent working by doing the "dreaming" kind of planning
As for the trip home if I bought that boat I mentioned,
I think there is a connection, but I would hardly call it navigable. It looks terrifying.
If I were you, I'd buy local. When I was first in the market for my boat (first and only), I looked at a boat in San Diego. I did the "dreaming" kind of planning and "realized" that it shouldn't take more than two weeks. What I didn't know at the time was how difficult, uncomfortable, and dangerous those two weeks would be. I ended up buying a boat in Seattle - a three day sail in principle that ended up taking three months. Go local