Alien Submarines

The USOs used by the aliens are big, blocky, shapes which resemble sea creatures and lack most forms of aerodynamics. They are able to dive and fly at breakneck speeds through the power of Zrbite and the resiliency of Aqua Plastics. USOs come in a variety of forms ranging from the tiny Survey Ships right up to the massive Dreadnoughts.

USOs are the aliens' sole method to move around Earth, and collect resources, so in theory, it would be possible to halt the alien advance if X-COM could maintain absolute naval superiority. Earth's forces do not initially have the resources required for such a task, and even if it becomes possible, the aliens have an vast resource supply and will not be set back by a war of attrition. In addition, alien undercover agents will continue to erode Earth's defenses from the inside.

Despite this, commanders should still down as many USOs as possible. At the very least, it may slow the aliens down some.

USO Overview

Craft	Size	Max Speed	Weapon Power	Weapon Range	Damage Capacity	UFO Grounded points	~Crew	~Loot
Survey Ship	Very Small	2,000	0	0	60	50	1	500k
Escort	Small	2,800	30	13	300	75	6	1.8M
Cruiser	Small	2,600	25	35	300	125	9	2.2M
Heavy Cruiser	Medium	3,800	60	20	450	250	15	3.5M
Hunter	Medium	4,500	50	144	63	250	13	3.6M
Fleet Supply Cruiser	Large	3,400	70	38	2,000	400	15	5.7M
Battleship	Large	4,200	120	50	1,400	500	9+5	5.0M
Dreadnought	Very Large	4,800	140	60	3,400	700	16+3	8.5M

Comments:

• The figures given in the in-game UFOpaedia are a factor of 8 too high. The values in this table have been corrected so they are comparable to Sub Armament ranges.
• Crew numbers depend on difficulty level as well as luck. Your mileage will vary.
• The monetary value of recovering such a USO if you sell almost everything. As this includes dead bodies and their former gear, the figure given may serve merely as rough orientation.

Weapons vs. USOs

Comparing the weapon range and damage capacity of UFOs to the range and damage of sub armaments, one can discern that:

• Any weapon, even the lowly Craft Gas Cannon, can be used against Survey Ships, since they can't shoot back.
• AJAX Torpedoes, with a range of 32km, are completely safe to use against Escorts, and can even be used to safely down Heavy Cruisers and Hunters.(Shouldn't the Heavy Cruiser be better than the Cruiser? Oh well...)
• D.U.P. Head Torpedoes or Sonic Oscillators should be used against Cruisers due to their weapon range of 35km.
• D.U.P. Head Torpedoes can fire on all but the Battleship and Dreadnought with impunity.
• Gauss Cannons, with a range of 20km, can be safely used against the Survey Ship, Escort, and Hunter. However, D.U.P. Head Torpedo-armed craft are of use against a larger variety of craft and Sonic Oscillators, once they become available, are superior in every regard.
• Sonic Oscillators can safely be used (even by Barracudas) against any USOs except Dreadnoughts. Even against Dreadnoughts, Sonic Oscillators are better than P.W.T. Launchers because a minimum of four P.W.T.-armed craft are required to down a Dreadnought.

Subs vs. USOs

• The Barracuda can always be used effectively against Survey Ships, for the Barracuda is faster.
• The Manta is faster than all USOs EXCEPT the Dreadnought.
• The Hammerhead can intercept all USOs except the Hunter, the Battleship, and the Dreadnought, which must slow down in order for the Hammerhead to catch up.
• The Leviathan is 1000 speed units faster than even the mighty Dreadnought and can intercept all alien USOs.