Figure 11-12.--Reference electrode assembly.

are available in the following three sizes: 2 feet (40

Anode to anode, anode to electronic log

amperes), 4 feet (75 amperes), and 8 feet (150

equipment, and anode to reference cell

separation should be a minimum of 40 feet.

amperes).

Installation of the anodes should be placed to

Anodes should not be installed within 15 feet

maintain a uniform potential throughout the under-

of a sea chest or pipe discharge.

water hull. The following is a list of anode locations:

Reference Electrode.-- The reference electrode

(fig. 11-12) is a silver/silver chloride type constructed

-- Placement should be at least 5 feet below the

of a silver mesh screen that has been treated with silver

light-load waterline.

chloride. It is bolted to the exterior hull of the ship and

One- and two-screw ships will have one set of

is insulated from the ship by a polyvinyl chloride

holder. A stuffing tube is used to pass the cable from

anodes located more than 10 feet, but less than

the electrode through the hull to the controller. The

50 feet, forward of the propeller plane.

controller measures the potential of the hull versus the

-- Four-screw ships will have two anodes located

reference electrode, and signals the power supply to

between the forward and after propeller planes,

increase or decrease current output as required. This

is to reduce the potential difference between the hull

one port and one starboard.

potential and the preset desired potential. Two

Anodes should be mounted in an area that

reference electrodes are installed for each controller.

experiences minimum water turbulence and

One reference electrode is selected for the primary

control; the other reference electrode serves as an

that is protected from mechanical damage.

Figure 11-12.--Reference electrode assembly.

11-12