Test the earth bonding link betweenthe ship's structure(a point adjacent to the ship earth stud),and the earth stud ET2 on the SAP (see fig.4.31).
Use a test current of least 10 amps,measure the voltage drop,and confirm than the resistance does not exceed 0.1 Ohm.
If the test fails,repair or replace the earth bonding link and perform the test again.