a total savings of more than each. The shorter Mark 13 also took up less deck space. The racks took advantage of the Mark 13's air-drop capability by simply allowing the torpedoes to roll over the side, eliminating the risks of a "hot run" within the tube and the flare of burning grease that sometimes gave away the PT boat's position upon firing. The Mark 13 also had the advantage of a significantly larger warhead ( vs. ), containing the significantly more powerful explosive Torpex, which was approximately 1.5 times more powerful per unit of weight than TNT. The Mark 13's shorter range and slower speed were considered acceptable tradeoffs for boats that usually operated at night and relied on stealth to reach firing position. See also Mark 21 Mod 2 torpedo, a development for use in the AUM-N-2 Petrel missile. Mark 25 torpedo GT-1 (missile) References External links – This film shows examples of several attack profiles developed by the US navy using Caltech research. World War II naval weapons Torpedoes of the United States Aerial torpedoes World War II weapons of the United States Weapons and ammunition introduced in 1936