The Americas are rather strange, in that there is not a large amount of of seas that cut through it. This is probably the biggest thing that distinguishes it from the Europe it draws so much from, culturally. The major military naval bases are found on the Atlantic Seaboard, Vancouver Sound, the Gulf of Mexico, and the Caribbean sea. The Gulf of St. Lawrence and Labrador Sea are generally too cold and sparsely populated for major battles to be waged there. However, the Great Lakes tend to serve as something of a de facto sea, with kingdoms guarding the canals that connect them. There's also the Mississippi River, which connected to both the Ohio and Missouri ultimately provides something of an interstate for the feudal core. Largely, the river system is used for trade, but it's very common for warlords to create river barges to raid these ships, or blockade them for ransom. However, these are generally means to and end, and not a lot naval strategy is used for them.
There are no missiles, or even canon fire anymore, so fleets have only the most basic of ancient projectiles at their disposal. However some allow themselves to be pretty inventive. Even though the ships don't resemble the large galleons of the age of exploration, they're relatively sophisticated, as coastal cities were able to at least glean some knowledge from the past, and have a fundamental understanding of nautical schematics.
The United States is the supreme naval power of the coast, with most ships of the Northern Atlantic trying to copy their jealously guarded designs. here, ships are made for longevity, and the ability to hold heavy cargoes. Marine soldiers are taught mostly endurance, for both the long winters and the long voyages. Northern ships have sturdy, thick hulls which are able to provide decent (by the standards of the time, anyways) barracks for the soldiers.
In the Caribbean and Gulf, warfare is played a lot like "capture the castle", which involves conquering and securing various island port bases. If fleet is particularly good at what they do, they can have islands full of provisions and weaponry for years to come. Many islands however, are full of leftovers from eradicated fleets who took their secrets with them to the bottom of the ocean. The heavy rains and winds of hurricane season means ships are made from more flexible, durable wood--usually balsa. One of the favored techniques of the Caribbean is to shoot fiery arrows at the ship.
Lake Navies are somewhat part time, as the winter freezes the waterways, leaving them to only b engage each other other during the summer. This lakes can also not hold as much weight. As a result, naval battles in the Great Lakes turn largely into all-or-nothing bloodbaths, attempting to storm forts as soon as they can, and do as much damage to the other ship as possible. Siege weapons such as trebuchets are sometimes even mounted to ships, resulting in a heavy amount of collateral damage on the "Drinking Sea".