I’m not so sure about a big navy… I don’t want to get over-confident, but now that we’re Average to BABE, strong to everyone else we know, and have a peace treaty with everyone we’ve met, it seems terrifically unlikely that we’re going to face an invasion before we have our Hwach’a. From there, it’s a short jump to Cavalry and then Railroads… which we have VERY good odds of getting for free, as long as FREE goes along with the MAAP II.
With Cavalry and rail lines, it’s hard to see how anyone can even bother us before Bombers. At that point, fielding a fleet of fast moving Destroyers (12.8.8) will make terrific sense. (Destroyers are the fastest moving ship in the game, they eat Transports (1.2.6) for lunch, and can even take on a Battleship (18.12.5) if needed.)
Until then… well, I think we need a couple Galleys to help us settle the nearby islands (if we can beat BABE to them) and to confirm/deny the existence of any more sea lanes. After that, I just don’t see having any boats being worth the 2gold upkeep in our Republic. It’ll be easier and more cost effective to kill units on land (in the unlikely event we’re invaded), and Galleys are on the transport upgrade path… so no reason to keep them for upgrades either.
Ideally, our AC’s and some horses from The Chamber will just keep us to Average with BABE, and that’s good enough. Otherwise, we’ve got a LOT of domestic building to do if we want to win a Space Race… so I’d argue we focus on that, and not get worried about an invasion till the Late Industrial Age.
(assuming of course, that BABE doesn’t change their mind on the treaty, get really hostile all of a sudden, and massively run-up their power score.)