Partials/Speed system

Speed value of a ship can take the following values: Initially, a ship is either slow or fast, the speed can be increased (from slow to fast to fast+ to fastest) using the engine synergy, by equipping a turbine (can be equipped in the expansion slot) and one or more boilers (Enhanced Kanhon Type Boiler and New Model High Temperature High Pressure Boiler) on a ship. The effects are
 * Slow (低速)
 * Fast (高速)
 * Fast+ (高速+)
 * Fastest (最速)
 * Increase in speed, slow ships will be fast and will count as fast for branching rules. It is also assumed that fast+ and fastest will have their own branching rules in the future.
 * Currently, it is unknown if there is an increase in evasion because of a higher speed and/or the engine synergy.