The yacht's sewage treatment plant (STP) has been showing reduced treatment performance for several weeks, though it still technically discharges within visible/odour limits. What should the Chief Engineer do?

A. Continue as normal — if there is no visible problem, the system is working adequately

B. Investigate the cause of reduced performance (e.g. aeration issues, chemical dosing, overloading) and arrange repair/servicing — a degraded STP may not be meeting the effluent quality standards required by MARPOL Annex IV even if the discharge appears visually acceptable, and continuing to discharge from a malfunctioning unit risks a pollution non-compliance

C. STP performance only matters in port, not at sea

D. Switch to direct overboard discharge of untreated sewage until the unit can be serviced

A. All plastics must be retained on board for discharge to a port reception facility — discharge of plastics into the sea is prohibited under all circumstances

B. Plastics may be burned in the incinerator and the ash discharged overboard

C. Plastics can be discharged if ground down to less than 25mm

D. They may be discharged overboard once the vessel is more than 12nm from the nearest land

A. Only the engineer needs to be present; deck crew are not involved

B. SOPEP equipment only needs to be available if bunkering more than 50% of capacity

C. Nothing specific — bunkering is routine and does not need pre-checks

D. A pre-bunkering checklist completed (hose connections, drip trays, communication with the barge/terminal, spill response equipment ready and accessible), a dedicated watch maintained throughout, and SOPEP equipment immediately available