A torpedo boat is a relatively small and fast naval ship designed to carry torpedoes into battle. The first designs rammed enemy ships with explosive spar torpedoes, and later designs launched self-propelled Whitehead torpedoes. They were created to counter battleships and other slow and heavily armed ships by using speed, agility, and the power of their torpedo weapons. A number of inexpensive torpedo boats attacking en masse could overwhelm a larger ship's ability to fight them off using its large but cumbersome guns. An inexpensive fleet of torpedo boats could pose a threat to much larger and more expensive fleets of capital ships, albeit only in the coastal areas to which their small size and limited fuel load restricted them.