Preliminary Rules

[Nobody]

Something just crossed my mind and I would like to hear your opinions.

In this world we're just rediscovering how to build (military) ships from history books, right? However, a lot of thing you need on a larger ship can't be found in books, especially if they become bigger you need to put more and more thought into thing you might not realized are even there.
Therefore I propose a tech tree limiting the size of ships, to like 200, 500, 1000, 2000, 4000, 8000, 16000, 24000, 36000, 54000... tons. I would choose max displacement, but that doesn't really matter and civil freighters should be allowed to be several times bigger as they consist mostly out of cargo space.
I would expect the technology for the next step in size to be available around the time were the first ship that approaches the limit is launched, so we should be able to lay down something that resembles a cruiser, after building coast patrol ships, in the second year.

[The Rock Doctor]

I see where you are coming from but I want to avoid artificial constraints on ship size where possible (granted, it is not always possible...)

I could entertain a higher cost to build larger ships at first, though.