Mark 15 torpedo

The Mark 15 torpedo was the standard American destroyer-launched torpedo of World War II. It was very similar in design to the Mark 14 torpedo except that it was longer, heavier, and had greater range and a larger warhead. The Mark 15 was developed by the Naval Torpedo Station Newport concurrently with the Mark 14 and was first deployed in 1938. It served as a replacement for the Mark 8 torpedo, Mark 11 Torpedo and Mark 12 Torpedo on surface ships with tubes that could accommodate the longer Mark 15; this primarily included destroyers built after 1930. Older destroyers, primarily the Wickes and Clemson classes, continued to use the Mark 8, as did PT boats early in World War II. During the war 9,700 were produced at Newport and at the Naval Ordnance Station Forest Park, Illinois. The Mark 15 had the same basic design problems that plagued the Mark 14 for the first 20 months following U.S. entry into the war, though this was not realized nearly as quickly by the destroyer crews as it was by the submariners. One major shared deficiency was the Mark 6 exploder, which usually caused duds. Another was a tendency to run deeper than set, often missing the target. Surface-combatant torpedo attacks very often included confusing splashes from gunnery and aerial bombs, obscuring smoke screens, and quick maneuvering to evade counterattack. Rarely was a destroyer given a chance for a slow, careful surprise attack. Torpedo results were difficult to estimate under these circumstances. The correction of the Mark 15's problems would depend on the submariners solving theirs. Another problem with early war-built Mark 15s was the substitution of zinc for cadmium as interior plating for air flask sections and water compartments, due to a wartime shortage of cadmium. This resulted in zinc oxide clogging water strainers, leading to erratic runs and engine failures. After the failure of corrosion inhibition efforts, the ultimate solution was to re-coat the areas with cadmium or phenolic resin (Heresite). The final straw for Admiral Chester W.