Duties of a 3rd Officer on board a Ship

The 3rd Officer (3/O), also known as the Third Mate, plays a vital role in the safe and efficient operation of a merchant ship. Positioned as the most junior deck officer, the 3rd Officer works under the guidance of the Chief Officer and Captain, but still carries major responsibilities related to navigation, safety, and ship operations. The duties of a 3rd Officer on board a ship include maintaining navigational watch, safety equipment, and assisting in cargo operations

Let’s take a detailed look at the key duties of a 3rd Officer on board a ship.

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1. Navigation Watchkeeping

• The 3rd Officer is usually assigned the 8–12 watch (morning and evening) on the bridge.
• Responsible for maintaining a safe navigational watch by monitoring the ship’s position, course, and speed.
• Uses radar, GPS, ECDIS, and other navigational equipment to avoid collisions and grounding.
• Keeps a lookout for traffic, weather changes, and navigational hazards.
• Records entries in the ship’s logbook during watch.

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2. Safety Officer Responsibilities

• On most ships, the 3rd Officer is designated as the Safety Officer.
• Maintains and updates the ship’s safety equipment like lifeboats, liferafts, lifejackets, immersion suits, fire extinguishers, and SCBA sets.
• Conducts safety drills such as fire drills, abandon-ship drills, and man-overboard drills in coordination with the Chief Officer.
• Ensures all safety equipment is inspected regularly and complies with SOLAS regulations.

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3. Medical Officer Role

• On smaller vessels without a full-time medical officer, the 3rd Officer may be assigned as the Ship’s Medical Officer.
• Responsible for maintaining medical supplies, medicines, and first-aid kits.
• Provides first aid to crew in case of accidents or medical issues under the Master’s guidance.

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4. Cargo Operations Assistance

• Assists the Chief Officer during cargo loading and discharging operations.
• Monitors cargo holds, tanks, or containers for safety and proper stowage.
• Prepares cargo-related documents and checklists when required.

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5. Maintenance

• 3rd officers need to maintain and inspect all Life Saving Appliances (LSA) and Fire Fighting Appliances (FFA) on deck under the chief officer’s supervision. 
• They have to keep the LSA and FFA maintenance records.
• 3rd officers need to maintain a spare parts inventory of all LSA and FFA onboard and have to prepare the requisitions as required.
• They have to inform about any shore inspection or service due for all LSA and FFA onboard. 
• 3rd officers have to maintain and correctly place all the muster lists and the LSA/FFA training manuals.
• They need to assist the 3rd engineer with any issues found in the engine room LSA/FFA. 

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6. Firefighting and Emergency Preparedness

1. Acts as fire officer during onboard drills and emergencies.
2. Supervises the maintenance of firefighting systems like fire extinguishers, fire pumps, hoses, hydrants, and fixed fire systems (CO₂, foam).
3. Ensures emergency escape routes and muster stations are well-marked and free of obstruction.

7. Training and Mentoring

• Assists in training deck cadets and junior crew members in navigation, safety, and seamanship.
• Demonstrates correct procedures for safety equipment handling and emergency drills.

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Conclusion

The 3rd Officer may be the junior-most deck officer, but his/her role is crucial to the overall safety and operation of the vessel. From navigation and safety to medical duties and equipment upkeep, the 3/O acts as the ship’s safety backbone while gaining experience to move up the ranks.

Being a 3rd Officer requires responsibility, vigilance, and a deep commitment to safety—qualities that prepare officers for senior positions in their maritime careers.