Sea Trade Routes?

[GDBreuer]

Playing some BTS for the first time in a long while and I have a question.

I was wondering if trade routes across sea tiles (not ocean tiles, but sea tiles) are impossible until Navigation is researched. Logically it doesn't make a whole lot of sense, since it seems like if I am able to produce galleys to reach a city across a few sea tiles, that trade routes should also be possible. So is there something I need to build/research to be able to trade across the sea, or am I stuck waiting until Navigation?

 

[Ghpstage]

You can trade along coast tiles, the water tiles that touch land (where Galleys can move), when you have Sailing. Sailing is the tech that allows Galleys and also allows you to trade along rivers .

 

[Polobo]

Sea Tiles?

You need astronomy for ocean tiles (unless within your cultural influence) to be considered when tracing a trade route. With sailing coastal tiles are considered, as well as river tiles outside of your cultural influence.

Culturally influenced rivers ALWAYS provide trade route access.

Early on if a galley can get somewhere without entering hostile territory then you can have a trade route to it.

Save Game / Screen Shot may help if you have a specific concern.

You need to be more specific on what a "sea tile" is if the above does not answer your question.