: BTW, how does one 'dip a toe' into telescope building and radios?

First, head to the library. Check for books on telescopes--may or may not be with books on star gazing. You can also head for periodicals and look for the magazines aimed at this audience, somethng like Sky and Telescope. Where are you located? near what major city? does that city have an observatory or a planetarium? If so you'll find that to be a central point for astronomy amateurs. The Adler Planetarium in Chicago, for example, has held classes in telescope making for decades. A former scoutmaster and his son made their 6" reflecting telescope through there. But You can do it alone, too. My high school's astronomy club made an 8" telescope, with the members grinding the main mirror over many weeks. Online suppliers can get you books and materials for doing this. Edmund Scientific in New Jersey (www.scientificsonline.com/) has a 35 page book with plans for 27 telescopes you can build:
http://www.scientificsonline.com/telescopes-you-can-build-book.html

Interesting link between astronomy and boating is the contribution of astronomy to navigation. There is a book titled "Longitude" which wsa made into a fascinating TV miniseries.

For radios you want to look online at a site run by the Amater Radio Relay League, a leading "ham" radio group. Their magazine is QST. The basic route for amateur radio operators is to take a class in person, or online, which would teach the basics of electronics and radio theory necessary to obtain an amateur radio operator's license. Some classes of broadcas licenses used to require the knowledge of Morse Code. (When I got my license 30 years ago there was a discussion at the FCC about dropping the Morse code reqirement, but I think it may still be in the rules for at least a General class license, or the current equivalent.) After an intro course you'll have enough knowledge to be able to read the next level of radio theory in the books for the higher level licenses. You acquire knowledge one step at a time. If the field keeps you interested, look at a community college for classes. You can probably register as a non-degree candidate, or just take the occasional class as a student at large.

For a really basic intro to both fields, ask if the library has Boy Scout Merit Badge books. There should be merit badges for electronics, astronomy, and radio. These are basic introductions to the fields, and they have bibliographies of other books for beginners.

Hope you have time for the new hobbies :)

PGJ