NavList:

Tom Sult, you wrote:
"But the current market is about 25 people world wide. If this was 1805...  now you would have a hit!"

Yes, it's on my list of projects when my time machine is ready. I'm bringing a crate with a thousand Casio fx-260 calculators back to donate to the US Navy in 1805 ...and then these United States of America shall conquer the world!! Wait, maybe I should think more carefully about time travel... ;)

But seriously, folks. I would say that the market today for a celestial "smart watch" is huge... tens of thousands minimum, but the problem is market-education. The vast majority of people who know about celestial navigation can imagine it in only one role: as a backup in the event that all electronics fail, and for that they can only imagine fiddling around on paper with tables from the 1970s. There is a role for modern celestial navigation today, and it does not have to be limited to Luddites, techno-phobes, and survivalists (in addition to those few hobbyists and fanboys --who, truth be told, also number more than 25!).

Could you make such a "wristwatch" device? Yes, easily, as an app. But here you'll bump up against the techno-phobia. As an app on a smartwatch, this is easy, but a great many users will argue that a smartwatch is not really a watch. They'll want something with more primitive technology inside, like an old-fashioned digital watch. And of course, you'll also bump against the usual problem with marketing of any apps: no one will know about your app unless you can advertise it somehow. That means money, and there's very little money in this market.

As an alternative to the full on "app approach", in my Modern Celestial Navigation (offered twice this fall, details here; also 19th Century Methods for the historians out there) I teach students that they can calculate Sun GHA and Dec, and also GHA and Dec for a selection of navigational stars. To do this they only need to carry around four pages of paper, which can easily fit inside a sextant box with one of those solar-powered calculators. And that makes the "sight reduction" easy, too. Celestial navigation does not require bulky tables, and modern celestial navigation should not be bound by 1970s thinking or by visions of the end of electronics. If you believe that the world is going to end so completely that all technology will come crashing down, then do tell: why are you thinking about post-apocalyptic yachting?! :)

Frank Reed
ReedNavigation.com
Conanicut Island USA