Your sub is armed with electrically-powered G7e torpedoes with contact detonators attached to 280kg warheads.
Once fired, a torpedo will run in a straight line at 20.6 m/s for 180 seconds (about 3700 m).
The warheads will only be armed once the torpedo has travelled 250m; if it hits a target inside that range, it will just "clang" off the hull.
You can fire a torpedo from any depth, and it will rise toward the surface at around 5 m/s. If you're too deep, and the target is too close, the torpedo will pass under it.
On the Chart view, the torpedo track line changes from transparent to opaque at the approximate point where the torpedo will surface; make sure that point is between you and your target.
A torpedo hit will apply 250 points of damage to the target; see the table of Ship Types for each ship's total hit points.
You also have an 88mm deck gun, capable of firing shells at targets up to 2000m away. The deck gun can obviously only be fired while your sub is surfaced; after surfacing, it takes the gun crew 10 seconds to prep the gun to fire once you've surfaced.
Your gunnery crew will handle the loading and distance arcing of the shells; you just need to aim left and right. Be sure to lead a moving target, with more lead the further away it is.
You can rotate and aim your gun 360 degrees; you don't need to worry about shooting your own conning tower, because video games.
Gun accuracy diminishes between 1000 and 2000 m.
A deck gun hit will apply 50 points of damage to the target; see the table of Ship Types for each ship's total hit points.
Your sub carries a small load of "Pillenwerfen" decoys. When launched, they will rise to a depth of 30 m. At that point, they're basically giant Alka-Seltzer pills, emitting a cloud of bubbles that looks to a sonar operator very much like a submarine.
If an escort's sonar ping hits the decoy before it hits you --that is, if the decoy is closer to the escort than you -- then the escort will go after the decoy instead of you.
Keep in mind that the distance is in 3D space, so even if you appear to be 100m closer in the Chart view, if you're at a depth of 140 m (110 m deeper than the decoy), the decoy will be closer than you.
Once launched, decoys will last for two minutes.
You have a very limited supply of decoys, so use them sparingly; they can mean the difference between life and death if you get cornered by multiple escorts.
No, you don't get any of these, but the enemy escorts do. They are armed with Mark VII depth charge cannisters, each with a 290 lb camatol charge.