Heated shot
Heated shot, or hot shot, is the heating of round shot before firing from muzzle-loading cannons. The purpose is to set fire to enemy warships, buildings, or equipment.
The use of heated shot dates back centuries and was stopped when vessels armored with iron replaced wooden warships in the world's navies. It was a powerful weapon against wooden warships, where fire was always a hazard. It was used mainly on shore batteries and forts because of the need for a special furnace to heat the shot.
The use of heated shot from a ship was so dangerous that it was against Royal Navy regulations. The American ship USS Constitution had a shot furnace installed for heated shot to be fired.[1]