Basic Strategy
The key skill of the game is getting your torpedoes to hit. That means either positioning yourself directly in front of or behind an enemy ship or leading your target so the torpedo goes to the spot the ship is *going* to be.
Your greatest element is surprise here - the first 2-3 volleys of torpedoes can be launched before the enemy sees you, especially if you keep your distance and partially submerge. The problem with this is that unless you have the godly Type XXI sub (which is Nazis only, and only in 1944 or after), you're slow while submerged and can't shoot enough torps at once to sink a major ship. Thus you really have two basic strategies:
- Get in front of the enemy convoy, then shoot a full volley of torpedoes at slightly different angles to hit different ships. Stay on course, and fire the second volley before the first hits, then submerge, turn, and run; you'll usually sink 1-2 ships this way.
- For example, if the enemy is heading East-Northeast, which it typically does by alternating headings of 66 and 96 degrees, you want to get in front of them at roughly 81 degrees, turn to the opposite heading, 261, and then fire torpedoes at angles 78, 80, 82, 84.
- Head in the same direction as the enemy convoy and fire butt torpedoes at them ;). This obviously only works with aft launchers (Type VII and Gato/Tench class), but has the benefit of letting you string out the enemy escorts since they'll take a longer time to catch you.
Once a convoy is on alert, all non-escort ships will start running to their destination at maximum speed. This means you won't catch anything faster than your sub, so it's important to prioritize your targets for your own survival and for maximum score (in sunk tonnage). Use the list below to pick out the most important targets, then line your sub up with one of them when you fire your torpedo spread to maximize the chance of hitting them:
- Aircraft Carriers, since they can send out planes which are near-unkillable and have a range of a couple hundred miles. See Carrier Runs below, these are so dangerous they merit a special strategy.
- Battleships, which are faster than any sub and give you a HUGE tonnage score if sunk
- Troop Transports, which are faster than any sub, so if they start running you won't catch them
- Oil Tankers, which are faster than all subs except the Tench/Gato class
- Destroyers, which can shoot fast enough to kill you unless you're already submerged and look up only in brief bursts with the periscope
All other targets are secondary. Escorts will head right towards you, making easier kills in the third torpedo volley, while merchantmen are slower than mainline subs and can be gunned down individually once the escorts are gone.
NOTE: Torpedoes are fired at the angle your periscope is facing, not the one you're heading. This doesn't make realistic sense for a WWII sub, but it's how the game does it. For a bit more realism, use the J key to lock your periscope to heading when firing forward torpedo bays.
Dealing with Escorts
In either strategy above, once a few torpedoes hit, the escort ships (Destroyers, Escorts, and Patrol Boats) will come rushing out to get you. If you want to have a chance at getting the rest of the convoy once the surprise is gone, you'll need to deal with them.
Escorts always make a beeline directly towards you, so if you change your heading to charge at them or flee directly away, then fire torpedoes straight at them, you'll almost always hit. Usually 2 torpedoes will sink one escort, but use three if you have a deck gun (again meaning Type VII or Gato/Tench), since you can use that sink tankers and merchants once the escorts are gone.
Often, though, you won't have torpedoes for all the escorts, so you'll also need to play defense. That's the whole point of being a submarine - you can dive and just vanish.
First, while you're using the above torpedo strategy, you have to avoid getting shot to pieces. To do that, dive to 50 feet so they can't see you. From there, raise your periscope and quickly lower it (P and O respectively) to make sure they're still on course, then shoot your torpedoes from underwater.
Then, once you're out of torps, dive to 600 feet and engage in silent mode. The escorts will drop depth charges, but they rarely reach 600 feet, and since you're in silent mode they'll lose track of you fairly soon. Let them get to around 10,000 feet away (a bit less than 1/3 of the total screen on the 7 mile map view) before you go back up, and you'll be able to continue hunting. Use periscope peeping until 15,000 feet or more; if you surface they'll probably see you.
If you take damage that stops you from going to 600 feet or are in shallow waters, go as low as you can and change headings often, which is some help in avoiding the depth charges. Use the side view (F7) to watch for charges on a collision course for you, and if you see some, release bubbles and debris to try to get something in its way.
Finally, if you have a lone patrol boat or a lone, heavily damaged destroyer or escort (hit by at least 2 non-dud torpedoes), you can get easy kills with the deck gun at night by firing at around 8,000 feet - their accuracy at long range suffers at night, but yours seems to be the same as during the day. Dive once they start closing in or firing at a faster rate.
Advanced Tactics
The above will let you win the campaign, but if you want to rack up some real high scores here's a few tricks:
- Carrier Runs: An aircraft carrier will send out planes for hundred of miles and generally spoil any chance of getting the rest of its convoy. To avoid this, you need to sink it first. The strategy is to first circle the fleet until you have a place in front of it that has a clear view of the carrier, then submerge and head on an intercept course for it. You need to be in front because you're slow submerged, and you need to be submerged so you can get close (ideally within 5,000 feet). Confirm you're on target with the periscope (once, quickly), then fire all torpedoes into the carrier. Hopefully it sinks, but don't wait for the hits, dive right away, because once the carrier's hit the whole fleet will be out for blood.
- Shitty Subs: The Type II and S-Boats are, to put it nicely, not very good. If you're stuck in one of these for a mission, you can't afford to take risks, so don't bother fighting the escorts - just burn your torpedoes and run away, diving as needed to avoid pursuit. In addition, ANY American sub using the Mark 14 torpedoes in 1941 to mid 1943 should be treated as shit, since more than half your torpedoes will be duds. Just fire double the number of torps at all targets and hope you get something - focus on escorts, because if you can down all of them you can still probably deck gun the merchant ships. The German T5 torpedo is similarly poor - it works, but it only travels around 5,000 feet!
- Ultra AA: Anti-air (AA) guns are pretty useless in the sim, because the planes will get to shoot you for about a minute straight before you can target them. However, against lightly-armored targets (all merchant ships, plus patrol boats if you're very close), they work wonders at under 1,500 feet, instantly killing anything they can damage. That's because it take no time to shoot AA, you can just press the button until you've got enough hits to sink the enemy.
- Range Advantage: Tench/Gato ships get 14,000 foot effective range on their deck guns, as opposed to 12,000 for the German ships and 10,000 for the S-class. Use it! Deck guns are fairly accurate all the way out to their max range.
- The Best Version: I highly recommend playing the DOS version of the game, as compared to the Commodore 64 or Mac versions. The main change is that in the C64 version, you can't use the auto-navigation (which is really just Time Compression: 1 Day) on higher difficulty levels, which makes things take forever. The Mac version is black-and-white only, which can make harder to tell what's going on sometimes (it's from the days before color Macs!)
Challenge Games
If you've mastered the strategies above and are looking for something more, try these!
U-Boat Ace - Otto Kretschmer was the real-life U-Boat ace of World War II, with 47 ships totaling 274,333 tons sunk before his capture in March 1941. Try a long campaign on Difficulty 4 and try to replicate this. You'll need to wipe out full convoys to make this work, and that will mean wiping out the escorts quickly and then using your guns whenever you have a Type VII sub.
Try Harder - Gato-class submarine Harder, commanded by Sam Dealey, sunk 4 Japanese destroyers in a single battle, the only submarine to achieve this. See if you can do this on Difficulty 4, not least of which because it's rare to spawn that many destroyers on lower difficulty levels.