TL;DR — Know the five fire classes (A, B, C, D, K), match the correct extinguishing agent to each, and follow the isolation-before-attack sequence; for flooding, the three damage-control priorities are stop flooding, maintain stability, then save the vessel — abandon ship only as a last resort.
What the Rule Says
Fire Classification
Shipboard fire is classified by the type of fuel involved. The five classes are: Class A (ordinary combustibles), Class B (flammable liquids and gas), Class C (energized electrical equipment), Class D (combustible metals — rare on small vessels), and Class K (cooking oils — galley fires). The correct extinguisher class must be matched to the fuel type. USCG Boatswain Manual Ch. 6 §6.1
The Firefighting Sequence
The prescribed sequence for attacking a shipboard fire is:
1. Alert the crew. 2. Isolate the fire — close hatches, ports, doors, ventilators, and louvers; shut off the ventilation system to cut off the air supply. USCG Boatswain Manual Ch. 6 §6.3 46 CFR §185.512 3. Shut off fuel and electrical supply to the affected space. 4. Attack with the appropriate extinguisher — for flammable liquid or grease fires, apply at the base of the flames; for ordinary combustibles, water may be used; do not use water on electrical fires. 5. If the fire is in machinery spaces, shut off fuel supply and ventilation and activate the fixed extinguishing system if installed. 6. Maneuver the vessel to minimize the effect of wind on the fire. 7. Confirm extinguished, then ventilate carefully to prevent re-ignition. 8. If unable to control the fire, immediately notify the Coast Guard and other craft in the vicinity by radiotelephone; move passengers away from the fire, have them don life jackets, and if necessary prepare to abandon the vessel.
Damage Control Priorities
Damage control on small vessels follows three priorities in strict order: (1) stop the flooding, (2) maintain stability, (3) save the vessel. If priorities one and two cannot be accomplished, abandon ship. USCG Boatswain Manual Ch. 5 §5.1
The recommended emergency instructions for a flooding situation direct the crew to:
- Close all watertight and weathertight doors, hatches, and airports to prevent taking water aboard or further flooding.
- Keep bilges dry to prevent loss of stability. Use the power-driven bilge pump, hand pump, and buckets to dewater.
- Align fire pumps for use as a bilge pump if possible.
- Check all intake and discharge lines that penetrate the hull for leakage.
- Never abandon the vessel unless actually forced to do so.
Man Overboard Response
The recommended sequence for a man-overboard situation is:
1. Throw a ring buoy overboard as close to the person as possible. 2. Post a lookout to keep the person overboard in sight at all times. 3. Launch the rescue boat and maneuver to pick up the person, or maneuver the vessel directly. 4. Have a crew member don a life jacket, attach a safety line, and stand by to enter the water to assist if necessary. 5. If the person is not immediately located, notify the Coast Guard and other vessels in the vicinity by radiotelephone. 6. Continue the search until released by the Coast Guard.
Crew Training Requirements
The owner, charterer, master, or managing operator must instruct each crew member upon first employment, prior to getting underway for the first time on a particular vessel, and at least once every three months, covering the duties expected in an emergency. 46 CFR §185.420
For vessels subject to the enhanced firefighting training requirement, the program must address:
- Location of firefighting appliances and emergency escape routes.
- Types and sources of ignition.
- Flammable materials, fire hazards, and spread of fire.
- The need for constant vigilance.
- Actions to be taken on board.
- Fire and smoke detection and automatic systems on board.
- Classification of fire and applicable extinguishing agents.
Emergency egress training must occur at least monthly while crew members are employed on board, and each time a crew member joins the crew.
Training conducted on a sister vessel may be considered equivalent to the initial, monthly, and quarterly training requirements.
All crew training must be logged or otherwise documented for review by the Coast Guard upon request. The log entry must include the date of training and a general description of the training topics.
MODU Examination Subjects
For MODU endorsements, examination subjects include fire prevention and firefighting appliances (organization of fire drills, classes and chemistry of fire, firefighting systems, firefighting equipment and regulations, and basic firefighting and prevention of fires) as well as emergency procedures covering fire or explosion, abandon unit, man overboard, heavy weather, and collision — required across all seven MODU endorsement categories. 46 CFR §11.920
Why It Matters on the Exam
Exam questions on this topic test three distinct skill sets: classification, sequence, and regulatory compliance.
Classification questions ask you to identify the correct fire class for a given scenario — a galley grease fire (Class K), a burning fuel oil spill (Class B), a smoldering mattress (Class A), an electrical panel fire (Class C). The wrong extinguisher choice is not just a wrong answer on the exam; applying water to a Class C fire or a Class B flammable liquid fire creates real hazards. USCG Boatswain Manual Ch. 6 §6.1
Sequence questions present a list of firefighting or damage-control actions and ask which step comes first, or which step is out of order. The exam frequently tests whether candidates know that isolation precedes attack — you close off air supply and shut down fuel and electrical before applying an extinguishing agent. Similarly, in damage control, stopping the flooding is always priority one before any concern about saving cargo or equipment. USCG Boatswain Manual Ch. 6 §6.3 USCG Boatswain Manual Ch. 5 §5.1
Regulatory compliance questions focus on training intervals and documentation. The quarterly (every three months) general emergency training interval and the monthly emergency egress training interval are both tested. The requirement to log training with date and description is a straightforward recall item. 46 CFR §185.420
The man-overboard sequence is also a recurring exam topic. The key tested points are: deploy the ring buoy immediately, maintain visual contact with a dedicated lookout, and do not terminate the search without Coast Guard authorization. 46 CFR §185.512
Common Pitfalls
Confusing Class B and Class K. Both involve liquid fuels, but Class K is specifically cooking oils in galley equipment. Exam distractors will offer Class B as the answer for a galley fire. USCG Boatswain Manual Ch. 6 §6.1
Selecting water for an electrical fire. The emergency instructions are explicit: do not use water on electrical fires. Class C requires a non-conductive agent. 46 CFR §185.512
Attacking before isolating. A common distractor places "use the extinguisher" before "close hatches and shut off ventilation." The correct sequence always isolates the fire first to deny oxygen before the attack begins. USCG Boatswain Manual Ch. 6 §6.3
Confusing training intervals. General emergency training is quarterly (every three months); emergency egress training is monthly. These are separate requirements and are tested independently. 46 CFR §185.420
Abandoning ship prematurely. The recommended emergency instructions state never to abandon the vessel unless actually forced to do so. Exam questions may present abandonment as an early option — it is always the last resort, after damage-control priorities one and two have failed. USCG Boatswain Manual Ch. 5 §5.1
Forgetting to log training. The Coast Guard may request documentation at any time. An undocumented drill is treated as if it did not occur. The log entry requires both the date and a general description of topics covered.
Terminating a man-overboard search independently. The vessel must continue the search until released by the Coast Guard — the master does not have unilateral authority to call off the search.
Quick Check
Q1 — A fire breaks out in the galley involving hot cooking oil. What fire class is this, and what extinguishing agent is appropriate?
Class K. A Class K extinguisher (wet chemical agent) is appropriate for cooking oil fires. Do not use water. USCG Boatswain Manual Ch. 6 §6.1
Q2 — What is the correct first action when a fire is discovered in the engine room?
Alert the crew, then immediately isolate the fire by closing hatches, ports, doors, ventilators, and louvers and shutting off the ventilation system to cut off the air supply. Shut off fuel supply to the machinery space. Then activate the fixed extinguishing system if installed. Attack with extinguisher only after isolation is complete. USCG Boatswain Manual Ch. 6 §6.3 46 CFR §185.512
Q3 — List the three damage-control priorities in order.
(1) Stop the flooding. (2) Maintain stability. (3) Save the vessel. If priorities one and two fail, abandon ship. USCG Boatswain Manual Ch. 5 §5.1
Q4 — How often must general emergency training be conducted for crew members, and how often must emergency egress training specifically be conducted?
General emergency training: upon first employment, prior to first getting underway on a particular vessel, and at least once every three months thereafter. Emergency egress training: at least monthly while employed on board, and each time a crew member joins the crew. 46 CFR §185.420
Q5 — A person falls overboard and is not immediately located. What action must the master take, and when may the search be terminated?
Notify the Coast Guard and other vessels in the vicinity by radiotelephone. Continue the search until released by the Coast Guard. The master may not independently terminate the search.
Q6 — What minimum information must be recorded in the crew training log?
The date of the training and a general description of the training topics.
Q7 — A fire breaks out in a compartment with energized electrical panels. A crew member reaches for a water hose. Is this correct?
No. Water must not be used on electrical (Class C) fires. A non-conductive extinguishing agent is required. Additionally, the electrical system supplying the affected compartment should be cut off if possible before any attack.
Q8 — Can training completed on a sister vessel satisfy the initial and periodic training requirements under 46 CFR §185.420?
Yes. Training conducted on a sister vessel may be considered equivalent to the initial, monthly, and quarterly training requirements.