So we played a gulf of bothnia game and here are my impressions.
I don't think I would make boats to take water control anymore.
Boats used to be effective for fighting land troops. (They were WAY too effective.)
Now they must be extremely weary of land troops because they will get sunk very easily by ranged infantry.
Boats firepower vs each other is also felt lackluster. They take a long time to kill each other. If you are trying to transport soldiers, I wouldn't be too worried about making a bunch of boats, just make a few and they'll probably survive to the other side unless hit by a fire boat.
So then what do you do with boats?
Fish,
Protect own fishermen, harrass other's fishermen
Transport soldiers
What do you not do?
Make combat boats for naval battles
Support land troops from the sea
I have no idea if this is more realistic so I won't comment about it. But if this is the way it is to be, the fact warships still take 3-4 pop space means you better not make too many.