
Skater
Skater is a light scout/AA ship. They offer very high speed, and a large line of sight. Use them in the beginning of sea battles to harass your enemy’s early base structures, and block their constructors from expanding. Their AA turret is weak and won’t stand a chance against more advanced aircraft, but during the T1 stage they provide useful protection from EMP drones and gunships. Always include a bunch of them in your fleet.
They are hopeless in a matchup with any other ships, so only use them as a support/scouting force.
Skaters are a faster than their CORTEX counterpart (Herring).

Dolphin
Dolphin is a fast and maneuverable light assault ship. They are equipped with two rapid-fire short-range plasma turrets, useful for raiding constructors in the early- to mid- T1 stage. In higher numbers they can overpower heavier ships, if your enemy isn’t paying attention.
Tip: Try to keep their broadside facing the enemy units while attacking, to maximize damage. Turrets are not able to shoot over each other, so only one will be used when facing the enemy head on.
Similar to the Pawn/Grunt matchup, Dolphins have higher damage but lower accuracy than their CORTEX counterpart (Supporter).

Construction Ship
Construction Ship is the T1 naval constructor. They are a good builder in terms of build power and speed - even a single one of these assisting the shipyard almost doubles its output. In addition to the Commander’s build list, they are able to produce more advanced T1 defenses, like the Floating Heavy Laser Turret, and give access to the T2 Shipyard. Each one increases your energy storage capacity by 50.
Use them for assisting the lab and quickly expanding, claiming underwater metal spots with underwater metal extractors.

Grim Reaper
Grim Reaper is a stealthy resurrection submarine. They are not visible to units on the surface if your enemy doesn’t have sonar nearby. Use them as support to provide repairs, reclaiming and resurrecting wrecks. They are relatively cheap and provide essential support to your navy maneuvers, don't forget to mix them in your fleet. Don't forget however the high energy cost of building and using them.
Resurrecting requires 50% of unit's energy cost.

Ellysaw
Ellysaw is an assault frigate. They are equipped with two light plasma cannons with decent range. They reside in the middle-ground between corvettes and destroyers. Their main use is defending against destroyers, as their range and speed allow them to outmaneuver the destroyers, though you need to use them in big numbers to pull that off.
Cost-wise, you can make two Ellysaws for every destroyer, so it is a good investment for fighting against them. However, they get easily destroyed by submarines, against which they have no weapon.
Ellysaws have a lower cost, but weaker armor and weapons than their CORTEX counterpart (Riptide).

Eel
Eels are stealthy assault submarines. They are equipped with a powerful torpedo launcher that can deal lethal damage to structures and ships within seconds. However, they are also very vulnerable due to having low health. It is kind of a glass cannon.
They are invisible to radar and to units on the surface, but are visible to sonar and other submarines.
If your enemy is not careful, you can sneak one or two of those into their base and cause havoc.
Their main use is destroying underwater metal extractors, and trapping fleets which don’t include proper anti-submarine units, like destroyers.

Corsair
Corsair is the heaviest of the T1 ships. Their biggest advantage is their durable armor and versatility. They are equipped with a powerful long range plasma cannon and a depth charge launcher. Their large range allows them to outrange all ships and torpedo launchers, which make them a great choice for pushing forward the front-line. They are also a good counter against submarines. However, due to slow movement and low maneuverability, they can get easily overrun by lighter ships. It is a good idea to provide them with an escort of lighter ships and repairing support.
They are costly and leave very precious wrecks, so take good care of them!
Corsairs have lower costs, but also weaker damage, compared to their CORTEX counterpart (Oppressor).

Bermuda
Bermuda is a radar jammer ship. They are used to make your units invisible to enemy radar, useful for planting traps and moving your fleet under cover. However, be aware that jammers do not make your units invisible, your enemy will spot them once they are within line of sight.
Combining a cloaked unit with a jammer makes a given unit totally invisible.
Usually, they are used to support Missile Cruisers, allowing the cruisers to sneak in close to the enemy’s shores. This lets you get within missile range of their base without being spotted, and unleash a lethal barrage of missiles.

Voyager
Voyager is a naval engineer. Similar to Butlers on land, these are used to assist T2 constructors and to quickly build T1 units in the field. Notably, they can build Floating Construction Turrets, plant powerful naval mines and produce combat units such as Destroyers, Platypus and Dolphins.
Don’t underestimate the damage you can do with a well-placed naval minefield. Use them to quickly secure large areas from hovercrafts, particularly early after you take control of the sea. Use mines until you are able to produce the proper T2 ships to defend yourself.

Advanced Construction Sub
Advanced Construction Sub is the T2 sea constructor. Their typical first tasks are upgrading your metal extractors, then building fusion reactors and advanced metal makers.
They have a higher build power than the T1 Construction Ship, and boost your metal and energy storage by 150. Guard them with T1 constructors or naval engineers to assist with building.
In addition to T2 economy structures, they are able to build advanced torpedo launchers and the underwater experimental gantry.

Barracuda
Barracuda is a submarine killer. They are used to hunt other submarines, especially T2 battle submarines. They deal bonus damage to submarines, offer better speed better maneuverability and can shoot from wider angles than other submarines. This allows them to counter battle submarines, which otherwise are lethal when faced with an unguarded fleet.
Always include a few of these in your T2 navy.

Dragonslayer
Dragonslayer is an anti-air ship. They are equipped with a powerful flak cannon and two light missile turrets, which makes them the best mobile anti-air unit in the game. Even just one of these can neutralize an entire fleet of lighter aircraft. As little as two can take out a Dragon. Always remember to include them in your fleet.

Paladin
Paladins are medium assault cruisers. They are like an upgraded version of Destroyers, and are a casual part of a T2 naval strike force. Equipped with a medium-range plasma cannon, two light laser turrets and a depth charge launcher, they are very versatile.
They are the fastest T2 ship, and it is useful to rush your enemy with a few of them at the beginning of T2 sea battle stage. They can easily take out any T1 units, and offer very good protection against hovercrafts.

Haven
Haven is an aircraft carrier and a mobile anti-nuke system. They can be used to repair damaged aircraft, but their main use is to protect against nuclear missiles. They are also equipped with both radar and sonar with medium range, to help your ships spot enemy units.
The anti-nuke interception range is lower than anti-nuke structures, but they are the only possibility in protecting the sea from nuclear strikes.

Serpent
Serpent is a battle submarine. They have unmatched range and damage, and pose a very big threat to unguarded fleets. Their role can be compared to that of the Sharpshooter bot on land. They can deal heavy damage from afar, but are vulnerable in close quarters combat, and are easily destroyed by submarine killers.
Use them to destroy heavy ships and protect the sea from T3 amphibious units. However, do not rely on them as the only part of your fleet, as they will fail in a clash with advanced torpedo launchers or submarine killers.

Longbow
Longbow is a missile cruiser. They are equipped with a heavy long-range missile launcher and a medium anti-air turret. Their main use is getting near the shore, then launching powerful missile barrages against land bases. As long as you can manage to get them close enough, it takes only a few missiles to completely level bases to the ground. Fortunately, their range surpasses all land-based defensive structures, even the Pulsar, so the only viable ways to stop them is to intercept them or hit them with tactical nukes.
A high missile trajectory enables them to shoot over mountains and other natural land barriers, which can stop other ships that use plasma cannons.
Take advantage of the element of surprise by combining them with jammer ships to hide them from enemy radar, and let them sneak in close enough before starting the bombardment.

Dreadnought
Dreadnought is a heavy battleship. They are equipped with two powerful long-range plasma cannons that deal significant splash damage. They prove useful at fighting other ships, but also excel at bombarding areas far inland from the coast, with most land units falling to their firepower.
Heavy armor makes them a difficult target to take down, however always make sure they are protected from battle submarines, which can easily turn them into shreds.

Epoch
Epoch is the the ARMADA flagship. They are the most powerful ships, and arguably the most powerful units in the game. They combine overwhelming firepower with unmatched range. Once you have one, it is usually game over for the enemy.
They are equipped with five plasma cannon turrets,. the two main cannons having the longest range. On most maps, it can bombard any point on land, if you manage to bring it close to the shore.
The other three cannons are used to kill off anything that manages to get closer. Thanks to their power, range and mobility they are able to destroy any T3 unit they clash with, as long as you can keep your distance.
They achieve maximum damage when facing their targets head-on, so they are able to shoot all cannons at once.
They are also equipped with medium anti-air missile launchers. However, they can be vulnerable to aircraft and battle submarines, so never leave them without an escort.