What information must be captured in MARPOL-compliant records when operating the OWS?

• A. Oil content in effluent and OWS operation
• B. Crew rest logs
• C. OWS maintenance and calibration records
• D. Vessel speed during discharge

Answer: (C)

MARPOL compliance hinges on proving the oily-water separator and its measuring system are kept in proper working order. Recording maintenance and calibration of the OWS ensures inspectors can trust that the equipment is functioning correctly and that any oil-content readings used to authorize discharges are accurate. Regular maintenance checks, sensor and meter calibrations, and the results of those tests demonstrate that the system isn’t drifting out of specification and that the MARPOL limit (oil in the effluent) can be reliably met.

Other information like crew rest logs or vessel speed during discharge aren’t related to proving the OWS is capable of compliant operation, and while oil-content readings may appear in discharge records, the most critical evidence of compliant operation is the maintenance and calibration history that confirms the equipment’s accuracy and reliability.