Figure 11-13.--Shaft grounding assembly.

are fitted with two brush assemblies on the silver-alloy

auxiliary to verif y operation of the controlling cell and

ring.

serves as a backup if failure of the primary cell occurs.

Reference electrodes are generally located on each

Rudder Ground.-- Rudders and stabilizers are

side of the hull, about halfway between the anode

grounded by brazing a braided, tinned-copper

sites. Reference electrodes are usually replaced

grounding strap, at least 1 1/2 inches wide, between

approximately every 10 to 12 years.

the rudder stock and the hull. To permit full rotation

Stuffing Tube.-- Stuffing tubes are required to

of the rudder stock from port to starboard, a large loop

insulate the electrical wires that pass through the hull

is required in the ground strap.

to anodes or reference electrodes.

Dielectric Shield.-- The dielectric shield prevents

Shaft Grounding Assembly.-- The shaft

shorting of the anode current to the hull and aids in

grounding assembly (fig. 11-13) consists of a

wider current distribution. The dielectric shield is

silver-alloy band, ring-fitted on the propeller shaft. It

applied as a thick coating around each anode. It

is electrically bonded to the shaft and is usually

consists of a high-solids epoxy with a high-dielectric

located in the shaft alley. Silver-graphite brushes ride

strength.

on the hard silver surface of the bands, electrically

OPERATION.-- The requirements for operating

connecting the rotating propeller shaft to the hull. This

the ICCP system on ships is provided in the

assembly is necessary to permit the anode current that

manufacturer's technical manual. The system should

flows through the water to enter the propeller blades

be operated at all times, except during diving

and return to the hull. A shaft grounding assembly is

operations, equipment repair, planned maintenance,

provided for each shaft. Ships of earner size or larger

Figure 11-13.--Shaft grounding assembly.

11-13