A submarine is a vessel capable of operating underneath the surface of the water. The ability to design and construct a submarine in Warship Craft is a true testament to the shipbuilder. As a general rule, operating underwater gives submarines several distinct advantages and disadvantages.
The most obvious advantage is the ability to dive beneath the surface, thus avoiding gunfire and nullifying most weapons. While far from enabling stealth in most conditions due to how spotting is done, it enables submarines to approach targets for torpedo attack. The ability to avoid damage from most weapons is certainly an advantage which arguably counter the numerous disadvantages of a submarine.
Possessing the ability to dive means certain drawbacks. Submarines are typically much slower than the average warship. Oftentimes, an opponent incapable of sinking a submarine is able to simply flee. Furthermore, a submarine could still be engaged with Underwater Torpedo Tubes, Depth Charges, Hedgehogs and Mines, all very powerful weapons that can kill a submarine in one shot.
In addition, a submarine is a very fragile vessel, and any damage could potentially disable its ability to dive properly without risking the submarine itself. On the surface, a submarine is a sitting duck. While many submarines are equipped with powerful, lightweight weapons such as the Mk 45 5 inch Gun or the Oto Melera 76mm Compact, they will usually have a few of them at most and is almost always outclassed by the firepower of all but the lightest of surface vessels.
A submarine has a somewhat limited but very powerful and effective choice of weaponry. The underwater torpedo tube and the mine-layer are the most common forms of submarine weaponry, because they are both capable of being used underwater. These two weapons both pack a large punch for there size but also both possessing very short ranges. Underwater torpedo's are best utilized en masse and at very close ranges, as they are both slow and inaccurate. A large spread at close range will deal very heavy damage to the target, if not sinking it. A new weapon making its way into use is the VLS missile launcher, which could potentially change the way submarines are used permanently.
Mines have a point blank range, they can be used as effective area denial weapons, as well as a point blank range, instant kill weapon. If deployed at longer ranges, a submarine can attempt to lure an enemy warship into it's "field of death", and at shorter ranges, a submarine captain can cross underneath an opposing warship and drop mines directly up into it. It can also be used to catch a pursuing skipper off-guard; coloring the mine layer to blue will lay blue mines, making them very difficult to detect on the surface. In addition, standard antisubmarine tactics call for approaching the submarine from behind to avoid your torpedoes before carpeting the area with depth charges, destroying it. Laying mines can kill these attackers easily.
Though, hypothetically any weapon can be fitted to a submarine, there are a few others that are often used, because they have been proven effective. Aircraft can and are often used to create carriers that cannot be sunk, while the planes do their work. Submarines are also often outfitted with Harpoon missiles, that can be launched at relatively safe distances, minimizing the risk of surfacing to fire them. And small guns, such as the Mk 45 and the Oto Melera are often added to combat small surface ships like low-tier gunboats, whose weapons will typically have a shorter range and inferior firepower to the deck gun and are difficult to hit with torpedoes.
The recent addition of the VLS Tomahawk missile launcher could affect the way submarines are built. These new weapons allow long range engagement rather than close range combat. With a very long range, of more than 80 kilometers, the VLS can devastate unprepared ships. Up to 16 VLS can be carried at one time, allowing even a small submarine equipped with these new weapons to become a powerful foe. However, it is still not recommended to rely on missiles for all your offensive firepower, as enemy CIWS can shoot them down before they impact the enemy ship.
While the ability to operate underwater is the submarines greatest asset, and allows it to get within range to fire it's weapons, it also creates interesting problems for maneuverability, control, and speed. To start with maneuverability and control; submarines when underwater must be controlled and so the throttle is often used, potentially in conjunction with the rudder, to control depth.
When a submarine turns, it pitches or rolls to one side or the other, altering the flow of water around it, and it's distribution of weight. This usually either causes the submarine to begin to surface or descend, depending on the design. A submarine captain must pay careful attention to the depth of a submarine, and the submarine's depth will often determine how fast it can be turned, because the submarine captain cannot turn too fast or he will risk sinking.
Submarine speed is also affected by it's underwater operation. By operating underwater, the submarine comes into greater contact with the water, creating more friction, slowing the sub down. Furthermore, a submarine's forward thrust is reduced, as some energy is used to dive. While it is very common to have battleships in excess of 194 knots the average speed that well built submarines achieve is much closer to the area around 90 knots (though exceptions exist). This usually gives the opponent of a submarine both a speed and maneuverability advantage, so submarine captains should always practice caution.
There are two key ways that WSC builders make submarines submerge: hydrodynamic submersion, and propeller driven submersion.
Propeller driven submersion relies on thrust from downward-facing propellers, usually on the bottom of the craft, in order to submerge. While easier to design, this type of submarine is never as fast as a hydrodynamic submarine, because it must use a significant portion of it's engine power to pull the submarine down.
Hydrodynamic submarines on the other hand rely on the shape and balance of the submarine in order to remain submerged. While much more difficult to design, they are capable of much higher speeds because all engine power is driven into forward motion.
Differences between BSC and WSC
While the games are very, very similar in many ways. WSC uses a slightly outdated version of the BSC physics engine. (one update behind). While a very small difference in larger ships, it does effect the density and diving of submarines enough that some subs will not directly cross over between the two applications. Slight re-balancing will probably be necessary, if you intend to use plans of a submarine built in BSC. However, the same principles that apply to BSC submarines will cross over to WSC, as well as any speed tweaking methods.