Apia-Carnova and Corundum have liquid sections big enough to justify ships(especially Apia-Carnova due to their island setup)
Maybe bone marrow from oil rigs that needs to be crystallized into bone. Not sure about Apia and Corrundum.
Maybe just have per-planet researches that require ship usage before rail supports can be placed on the oceans
By ship usage, I mean transporting stuff between islands
Extra stuff: I know they aren't very complete, but eventually I think adding some cargo ships sub-mods such as battleship, fishing trawler, port crane, ect to this pack could be good(obviously for much later)
