Submarines

Two things: a submarine drive and ballast it can change. The submarine drive is the engine that runs submerged and pumps the tanks (see Engines), and the ballast blocks are the tanks. With both fitted the dive controls appear in battle.

Hold E to flood the tanks and dive, Q to blow them and rise. Releasing the key holds the ballast where it is, not the depth: a boat that is still heavy keeps sinking. There is no automatic depth keeping.

• Guns, rockets and missiles do not work from a flooded mount. Shells and missiles stop at the surface.
• Underwater torpedo tubes launch only while submerged.
• Radar and fire-control fittings do nothing under water.
• Surface ships see a submerged boat only with working sonar, within 2.5 km, and islands block it.

• Depth charges are dropped or thrown by hand, one per press, and explode on a timed fuse. The Depth charges and mines view of Weapons gives each fuse and blast.
• Any torpedo that crosses the boat's position hits it, whatever its depth.
• Bombs that fall into the sea damage submerged parts inside their blast.
• Your sonar pings are heard by the submarine, so it knows it is being hunted.