Question 1

Why are zinc/aluminium blocks fitted to a ship's hull and rudder referred to as "sacrificial anodes"?

Accepted Answer

Because they have a more negative (less noble) electrochemical potential than the steel hull, so in the presence of seawater they corrode preferentially — "sacrificing" themselves — and protect the hull from electrolytic corrosion (cathodic protection) Sacrificial anodes (commonly zinc or aluminium) are fitted to the hull and other submerged steel components as a form of cathodic protection. Because these metals have a more negative electrochemical potential than steel, they act as the anode in the resulting galvanic cell, corroding preferentially while the steel hull (the cathode) is protected from corrosion. The anodes are consumed over time — "sacrificed" — and must be inspected and replaced periodically, typically during dry-docking.

Question 2

You're draining a thermal oil system that was running normally a short time ago. Before opening the drain point, what should you confirm?

Accepted Answer

That the system has cooled and depressurised, and you are positioned clear of the drain point's discharge path On the dredger MV Amazone, two crew members draining a thermal oil system after months of contamination were sprayed with hot oil, suffering severe burns. The investigation found company procedures lacked clear instructions for safe drainage — confirming the system has cooled and depressurised, and standing clear of the discharge path, are essential before opening any drain point on a hot oil system.

Question 3

A thermal oil system has been contaminated and needs draining for cleaning. The written procedure tells you to open the drain valve but doesn't specify a cooling-down period or PPE. What should you do?

Accepted Answer

Treat the gap as a hazard in its own right: apply a suitable cooling/depressurising period and full PPE before proceeding, and raise the procedure gap with the Chief Engineer The FEBIMA investigation into the MV Amazone incident found that although the crew followed company procedures, those procedures lacked clear instructions for safely draining a thermal oil system. A procedure that's silent on cooling time and PPE for a hazardous task is a gap to be closed before the job starts — not a green light to skip those precautions.