Oh, good point, we have to think about the ships... There will be no combat ships until the second age. Many of the naval units would be UUs, like the Swan Ships (a weaker transport ship, but cheaper and available earlier) for the Teleri, the Corsairs for the Haradrim, and several boats for Númenor. A sketch, without any values (but they should be expensive, in ME we didn't have many ships):
Work Boat: normal, available to all
Swan Ship: only ship available in the Age of Stars, only to the Teleri (transport ship)
Ship: first transport, no attack, available to all
Transport: better transport, not completely defenseless, available to all
Warship: first military naval unit, available to all
Siege Ship: can bombard cities, good against transports, slow, weak against warships, available to all
Scout ship: weak, but fast, good to exploration, available to all
High Ship: best naval unit, hybrid between Warship and Transport, only to Númenor (maybe Gondor/Arnor)
Fast Ship: best explorer ship, only to Númenor
Great ship: late game siege ship, available to all
Quick ship: late game warship, available to all
Corsair: ???, only to Harad