A recent thread concerning Japanese depth charges sparked my interest, so I did a bit of investigating.
The Japanese started the War (at least the portion that included the U.S.) with the "Type 95" Depth Charge. The specifications follow:
Date of design: - 1935
Date of service: - 1940
Total weight: - 325lb (160kg)
Explosive charge: - 220lb (100kg)
Sink rate: - 6 fps (1.9 mps)
Possible depth settings: - 98, 197, or 295 feet (30, 60, or 90 meters)
Note: Early War Type 95s only had the 30 and 60 meter settings, but this was quickly changed.
In 1943, the Japanese introduced an improved version called the Type 2; ....which came in three variants:
Date of design: - 1942
Date of service: - 1943
Total weight: - n/a
Explosive charge: - Model 0 231lb (105kg)
...........................Model 1- 357lb (162kg)
...........................Model 2 - 243lb (110kg)
Sink rate: - 9.9 fps (3 mps)
Possible depth settings: - down to 475 ft (145m) in 25 ft (7.6m) increments.
Both types could be launched from stern racks, or "K" and "Y" depth charge launchers.
Both of these Depth Charges had some interesting features. Unlike many of their Allied counterparts, the detonator did not sense hydrostatic pressure directly. Instead, it consisted of a variable orifice that allowed a cylinder to fill with water at a predicable rate. When the accumulating volume of water had moved a captive piston a certain distance, the charge was fired. This system had the advantage of making the Depth Charge immune to surface detonation, if it happened to land sensor side down. It was also vastly cheaper and more reliable than a complex hydrostatic pressure sensor.
Another interesting feature was that both types were equipped to deploy small, optional "******ing" parachutes, when launched from either "K" or "Y" guns. This allowed slower vessels to use shallow settings, and still get clear of the damage radius.
A PAIR OF "K" GUNS
A "Y" GUN AND RELOAD RACK