One of the biggest changes between this game and mine is the maintenance costs of ships. And, because I'm a truly colossal dork, I got my hands on an academic paper studying naval costs in the ancient world. Because things are quiet around here, I'll share the main takeaway.
In the First Punic War, about 5% of the cost of a navy was construction, and another 5% was maintenance (in the sense of keeping the ship itself in working order). The other 90% was crew costs. Keeping a galley out on the water for a month and a half cost more than building it did, because the ships were quite cheap, and the rowers were quite expensive. This is also why this sort of warfare rarely produced decisive results - losing a ship often meant its crew drowned, and thus didn't need to be paid. So them making it back to port was often
more expensive than just building a new ship and getting a new crew, because their wages for a trip could easily be more than the cost of a hull.
I don't claim this applies to our BattleTech game, of course. High-tech warfare is different than an era when the most expensive part of a ship is literally a solid block of bronze (the ram was big, and metal was expensive). But you guys seem like the sort of dorks who'd enjoy this bit of historical info.
Side note: The author of this paper is also the author of one of my favourite blogs. A lot of his writing is ancient or fantasy, but he's done a bit on sci-fi too:
https://acoup.blog/2019/11/29/collections-where-does-my-main-battery-go/