Figure 10-35.--Major components of an underwater log system.

slightly above the ON speed value in a decreasing

the exact scale zero because a limiting switch (not

direction because of the operating differential

shown in fig. 10-34) de-energizes synchronous motor

inherent in microswitch 200.

4 at a pointer indicator of approximately 1 rpm.

The full-scale indication should occur when the

Indicators

point of roller contact is exactly 1 inch from the

center of disk 30. The indicators provide for an

Indicators are installed in the pilothouse and

overspeed indication of about 10 percent above full

engine rooms to indicate the rpm of the associated

scale (1.10 inches disk radius) before limit switch 70

propeller shaft. An indicator consists of a positioning

is actuated.

synchro receiver and a revolving pointer that

indicates on a dial the rpm of the associated propeller

The indicator-transmitter can be provided with

shaft. The synchro receiver is driven by the

speed signal switch 200 to continuously energize a

positioning synchro transmitter in the associated

remote light or other signal at propeller speeds below

indicator-transmitter unit. The indicator is also

a specified value. The signal setting is adjustable

provided with a backing signal that is energized by

from about one-quarter of full speed down to about 5

the unidirectional mechanism in the shaft

rpm. As the speed of the propeller shaft decreases

transmitter when the propeller shaft rotates in the

from higher value above the switch operating point,

reverse direction.

yoke 15, bracket 205, and actuator screw 204 are

advanced along lead screw 16, until the roller and

UNDERWATER LOG SYSTEM

arm of stationary single-pole, double-throw (SPDT)

switch 200 are lifted by actuator screw 204. The

The underwater log system (circuit Y) measures

speed value at which the switch is operated is

and indicates the speed of the ship in knots and the

determined by the height of actuator screw 204,

distance traveled through the water in nautical miles.

above bracket 205. The speed signal switch is

adjusted by turning the actuator screw until the

desired operating point is obtained. After the switch

has been actuated in decreasing speed direction, it

will remain actuated at lower speeds down to zero.

Also, when the propeller speed increases, the OFF

or release point of the switch will occur at a value

140.158

Figure 10-36.--Exploded view of the sea valve

Figure 10-35.--Major components of an

and packing assembly with the rodmeter

underwater log system.

installed.

10-22