To facilitate the game, submarines are divided into different classes according to size, these are:
Attack eg Los Angeles
Boomer eg Resolution
Large Boomer eg Typhoon or Ohio
Though based somewhat on twentieth century terms, the sizes do not relate to the role of each submarine, for example, nearly all submarine tankers are boomer size (to be honest a lot of them are ex-missile boomers converted into tankers). Very small submarine-craft are described within the advanced rules.
Submarines are complicated devices, full of equipment.