M 1

M 3

A 1

A 1st

MA 1, 2, and 3

AA 1

AA 2

DM 1

Sea-bottom
conditions

Sensitivity reduced by
soft, sticky mud.

In the ooze and mud
of harbors or in
soft ground may lose
sensitivity and be
sweepable within a
radius of 500 ft.

Ocean swells in
shallow water

If ground hard -
pendulum oscillat-
ion may run down
battery.

Detonation
possible

If ground hard,
pendulum oscilla-
ton may run down
battery.

Possibilty of
use limited.
Pendulum action
same as in M 1.

Burying of mine
in soft ground
due to current

Detonation
possible

Become less sensitive

Subsequent tumbling
of mine stuck in
bottom may cause
detonation

Shifting of
botton due to
currents

Pendulum oscilla-
tion may run down
battery.

Detonation
possible

In strong currents
detonations may result.

Pendulum oscilla-
tion may run down.
battery.

Same as A1

Same as MA 1

Movement of mine
on hard bottom
due to currents

Pendulum oscilla-
tion may run down
battery.

Detonation
possible

Detonation possible

Pendulum oscilla-
tion may run down.
battery.

Same as A1

Same as MA 1

Magnetic dis-
turbances

From 0° to 60° lat-
itudes chaces of
firing less than
once per year. In
higher latitudes,
chances greater.

From 0° - 30° latitude
firing chances less
than once per year.
30° - 60° up to twice.
Over 60° up to 12.

Same as MA 1

Index numbers
showing great-
est depth ef-
ficiency (0- to
greatest effic-
iency)

4

5

2

6 or 0

3

1

0

3

Target accuracy

good

good

inaccurate

uncertain

good

good

good

Estimated life

2 years

2 years

6 months

6 months

6 - 12 months

6 months

6 - 12 months

Ship speed

moderately dependent

slightly independent

slightly independent

strongly dependent