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	18	500	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:

• Weapon Range: 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.
• Loot is the monetary value of recovering such a USO if you sell almost everything. This includes dead bodies and their former gear, so the figure is only a rough approximation.

Weapons vs. USOs

Craft	Vmax
Barracuda	2400
Manta	4600
Hammerhead	4030
Leviathan	5800

Armament	Damage	Range (km)	Accuracy	Reload Time (s)	Shots
Craft Gas Cannon	15	8	25%	3	200
AJAX	60	32	70%	17	6
D.U.P. Head	110	50	80%	21	3
Gauss Cannon	90	20	35%	4	50
Sonic Oscillator	150	55	50%	5	100
P.W.T. Cannon	200	60	100%	28	2

If your craft is faster, the USO cannot escape; if your weapons have a higher range than the USO, you'll be entirely safe from return fire.

• 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 catch Survey Ships for the Barracuda is faster, but it often cannot dive deep enough to engage its target.
• 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.