The U.S. Navy makes no separate designation of Japanese depth charges but uses in-stead, the translated Japanese names. Thus, one cannot tell, by locking at the name, whether the type has been recovered or not.

Three types of Japanese depth charges have been recovered and additional types have been reported from intelligence sources. The pistols of all charges, both recovered and reported, wht the exception of "Experimental Manufacture Use 120KG Depth Charge" operate on seepage-hole principle. Water gradually seeps into a cylinder and builds up sufficient pressure to fire the depth charge. Operation of pistols using this principle is dependent upon the rate of flow of water through an orifice rather than on hydrostatic pressure alone.

The explosives used in Japanese depth charges are the same as those used in mines, with the exception of Type 97. The general characteristics of this explosive are as fol-lows:

Type 97 – Composed of Hexanitrodiphenylamine (HND) 40% and Trinitrotoluene (TNT) 60%. This explosive is used in a cast form and has a somewhat darker color than Shi-mose. It has a melting point of 70° - 80° C. and is slightly less powerful than TNT. The explosive is very toxic and must not be handled by the bare hands.

JAPANESE DEPTH CHARGES

Type

Diameter

Length

Charge

Depth Setting

Described
on Page

88

17".8

29".7

326#

80' or 150#

32

91, Model 1,
Modif. 1

17".8

29".7

220#

80' or 165'

32

93

Un-
known

36"

Un-
known

100'

32

95

17".75

30".5

220#

100', 200'

29

95 Modif. 1

17".75

30".5

325#

100', 200', 300'
390', 490'

29

95 Modif. 2

17".75

30".5

242#

Unknown

29

96, Model 1

Un-
known

Un-
known

242#

100', 200', 300'

32

2, Modif 1

17".56

30".5

357#

100', 200', 300'
390', 490'

28

2, Modif. 2

17".56

30".5

220#

Unknown

32

Exp. Use
120KG

Un-
known

Un-
known

Un-
known

Delay igniter
used

31

YOKO

Un-
known

Un-
known

55#

130', 165'

33