Safety, Fire & Survival

The fire triangle and tetrahedron:

A fire needs three things: FUEL, HEAT (an ignition source), and OXYGEN — the classic fire triangle. The fire tetrahedron adds a fourth element, the uninhibited CHEMICAL CHAIN REACTION, that sustains combustion. Every method of extinguishing attacks one or more of these: cooling removes heat, smothering removes oxygen, starving removes fuel, and certain agents (dry chemical, halon/clean agents) interrupt the chain reaction.

Class A — ordinary combustibles:

Wood, paper, cloth, bedding. Leaves an ash. Best extinguished by COOLING with water (or water-based agents).

Class B — flammable liquids and gases:

Oil, fuel, grease, paint, solvents. Extinguished by SMOTHERING / excluding oxygen — foam, CO2, or dry chemical. Never use a solid stream of water on a Class B liquid fire; it spreads the burning liquid.

Class C — energized electrical equipment:

Switchboards, motors, wiring that is live. Requires a NON-CONDUCTING agent — CO2 or dry chemical. De-energize the circuit if possible, which then reduces it to a Class A or B fire.

Class D — combustible metals:

Magnesium, titanium, sodium, aluminum swarf. Requires SPECIAL dry-powder agents; water can react violently. Rare aboard most vessels but examinable.

Class K (galley):

Cooking oils and fats in commercial galley equipment. Extinguished with wet-chemical agents that saponify the oil. (Internationally grouped with Class F.)

Water:

Cools (removes heat) and is ideal for Class A. Delivered as a solid stream (reach) or a fog/spray (greater surface cooling, heat-absorption, and crew protection). A high-velocity fog also protects firefighters advancing on a fire. Do not use solid streams on liquid or energized-electrical fires.

Foam:

Forms a blanket that smothers Class B liquid fires and seals the surface against re-ignition; it also has a cooling effect. AFFF (aqueous film-forming foam) is the common shipboard type. Foam is the agent of choice for large liquid spills/fires on deck and in tanks.

Carbon dioxide (CO2):

A non-conducting gas that smothers by displacing oxygen and leaves no residue — good for Class B and C, machinery spaces, and electrical fires. CO2 total-flooding systems for engine rooms require evacuation and a warning alarm BEFORE discharge because CO2 is an asphyxiant; account for all personnel and seal the space.

Dry chemical:

Interrupts the chemical chain reaction; fast knockdown on Class B and C. Leaves a residue and gives no lasting cooling, so re-ignition is possible if the fuel is still hot.

Clean agents (replacing Halon):

Halon interrupted the chain reaction and was excellent for spaces with sensitive equipment, but is being phased out for environmental reasons; modern clean agents (e.g., FM-200/HFC-227ea, Novec) serve the same role.

Fixed systems and detection:

Vessels carry fixed systems (CO2 or clean-agent flooding for machinery spaces, fixed foam for tankers), fire main with hydrants and hoses, portable extinguishers rated by class, and detection (smoke, heat, flame). Fire pumps and the emergency fire pump (in a separate space) maintain pressure on the fire main.

Common causes aboard:

Oil leaks onto hot surfaces (the leading machinery-space cause — lag hot pipes and keep oily rags out), electrical faults and overloaded circuits, smoking in unauthorized spaces, galley fires, hot work (welding/cutting) without a fire watch, and spontaneous combustion of oily rags. Good housekeeping — controlling oil, rags, and rubbish — is the first line of defense.

Hot work permits:

Welding, cutting, and grinding require a permit, a gas-free check where flammables may be present, removal/protection of nearby combustibles, a charged hose or extinguisher, and a fire watch maintained during and AFTER the work.

Fire and emergency drills:

SOLAS and U.S. regulations require regular fire and abandon-ship drills (for SOLAS vessels, generally within 24 hours of leaving port if more than 25% of the crew is new, and at intervals — typically monthly, weekly on some passenger ships). Drills exercise the muster list, donning gear, starting pumps, and using the fixed systems.

The muster list (station bill):

Posted throughout the vessel, the muster list assigns every crew member a duty and a station for fire, abandon ship, and man-overboard, and explains the emergency signals. Each crew member must know their assignments before getting underway.

Fireman's outfit and SCBA:

Vessels carry fireman's outfits — protective clothing, boots and gloves, helmet, a fire axe, a safety lamp, a lifeline, and a self-contained breathing apparatus (SCBA) — for entering smoke-filled or oxygen-deficient spaces.

Lifejackets:

Designed to turn an unconscious person face-up and keep the mouth clear of the water. SOLAS lifejackets carry a whistle and a light, are donnable in about a minute without help, and are sized/marked for the vessel. Stowed at the muster station and in cabins.

Immersion (survival) suits:

Insulated, watertight suits that dramatically slow body-heat loss in cold water and add buoyancy; required on many vessels operating in cold waters. A crew member should be able to don an immersion suit in under 2 minutes (the SOLAS standard, including a lifejacket if the suit is not inherently buoyant). They are the single biggest factor in cold-water survival time.

Thermal protective aids (TPAs):

Bags or suits of waterproof, low-conductivity material carried in survival craft to retain the body heat of a recovered, wet survivor — used in the liferaft/boat, not for in-water swimming.

PFD types (Coast Guard):

U.S. recreational/commercial PFDs are described by type/performance (offshore, near-shore, flotation aid, throwable, special-use). Offshore lifejackets give the most buoyancy and best turning for rough, open water; throwable devices (Type IV — a ring buoy or cushion) are thrown to a conscious person and are NOT a substitute for a worn PFD.

Ring lifebuoys:

Throwable buoys stationed around the deck, some fitted with a self-igniting light and/or self-activating smoke signal, and some with a buoyant lifeline. At least one near the bridge is rigged to release a light and smoke for man-overboard marking.

Lifeboats:

Rigid boats launched from davits, carried on many cargo and passenger vessels. Totally enclosed lifeboats protect occupants from fire, weather, and capsize (they self-right) and are required on tankers and many vessels. Free-fall lifeboats launch by sliding down a ramp from the stern, clearing the vessel quickly.

Inflatable liferafts:

Stowed in fiberglass canisters in cradles and inflated by a CO2/nitrogen bottle when deployed. They are equipped with a canopy, sea anchor (drogue), bailer, paddles, signaling gear, water, and rations. Common on smaller commercial vessels and as supplementary craft.

The painter and automatic inflation:

The liferaft's painter line both inflates the raft (pull it to fire the gas bottle) and tethers the raft to the vessel. You board, then cut the painter to get clear.

Hydrostatic release unit (HRU):

A pressure-activated release that automatically frees the liferaft canister if the vessel sinks before the raft can be launched manually. At a depth of around 1.5–4 meters the water pressure cuts the lashing; the raft floats free, the painter goes taut as the vessel sinks, the raft inflates, and the painter's weak link then parts so the inflated raft is not dragged under. The HRU is the device that ensures a raft floats free from a sinking ship.

Launching appliances and capacity:

Davits lower lifeboats; some rafts launch by davit, most by throw-over. Survival craft and their launching gear are tested and maintained on schedule, and total survival-craft capacity must accommodate everyone aboard (with regulatory margins and distribution by side).

Before abandoning:

Send a distress alert (DSC/Mayday, EPIRB), don warm clothing and an immersion suit and lifejacket, take extra water and any portable signaling gear, and — if possible — step DOWN into the craft to stay dry. Avoid jumping into the water; if you must jump, check below, hold the lifejacket down, cross your legs and cover your nose and mouth.

EPIRB (Emergency Position-Indicating Radio Beacon):

Transmits a distress signal on 406 MHz to the COSPAS-SARSAT satellite system, identifying the vessel (registered beacon ID) and — with built-in GPS — its position, plus a 121.5 MHz homing signal. A float-free EPIRB is mounted in a bracket with its own HRU so it releases, floats, and activates automatically if the vessel sinks. Register the beacon and keep the registration current.

SART (Search and Rescue Transponder):

A radar transponder that, when triggered by a rescue vessel's or aircraft's 9 GHz (X-band) radar, paints a line of twelve dots on the radar screen pointing to the survival craft. It is the primary homing device for bringing rescuers to the raft once they are within radar range. (AIS-SART is an alternative that sends position reports to AIS receivers.)

Pyrotechnic distress signals:

Carried in survival craft and aboard: red hand flares and red parachute (rocket) flares for night, and orange smoke signals for day. Use the parachute flare to attract attention at a distance and the hand flare to pinpoint your location for a searcher that is already near.

GMDSS and the radio Mayday:

Under GMDSS, a DSC distress alert on VHF Ch 70 or MF/HF carries the vessel ID and position at the push of a button, followed by a voice Mayday on Ch 16. Know the spoken distress format: "MAYDAY" ×3, vessel name, position, nature of distress, number aboard, and assistance required.

Cold-water immersion stages:

- Cold shock (first 1–3 minutes): an involuntary gasp and hyperventilation — the greatest drowning risk; keep your airway clear and your head above water until breathing settles. - Cold incapacitation (first ~10–15 minutes): hands and limbs lose function ("swim failure") — do anything requiring your hands (board the raft, secure yourself) EARLY, while you still can. - Hypothermia (after ~30 minutes onward): core temperature falls, leading to unconsciousness and death. Survival time depends heavily on water temperature, clothing/immersion suit, and behavior.

Reducing heat loss in the water:

Do NOT swim unnecessarily — swimming pumps warm water out of your clothing and speeds heat loss. Adopt HELP (Heat Escape Lessening Posture): draw the knees to the chest and arms to the sides to protect the high-heat-loss areas (groin, armpits, chest). Two or more people huddle together, fronts in, sharing warmth. Stay with the vessel or wreckage if it is afloat — it is easier to spot than a swimmer.

In the survival craft:

Stream the sea anchor (drogue) to slow drift and keep the raft from capsizing and to stay near the distress position; close the canopy and bail to stay dry; ration water (typically about 0.5 liter per person per day where supplies allow) and do NOT drink seawater. Use anti-seasickness tablets — seasickness worsens dehydration. Post a lookout for ships and aircraft and keep signaling gear ready.

Dehydration and the sun:

Conserve water from the first day; do not drink seawater or urine. Protect against sun and exposure. Eat little if water is short, because digestion uses water.

Primary survey — ABC:

Airway, Breathing, Circulation. Ensure the airway is open, the casualty is breathing, and there is a pulse / no severe bleeding — treat life threats in that order before lesser injuries. Modern CPR emphasizes early chest compressions (C-A-B in resuscitation), high-quality compressions, and early defibrillation where an AED is available.

Bleeding:

Control external bleeding with direct pressure and elevation; apply a tourniquet for severe, uncontrolled limb hemorrhage. Watch for and treat shock.

Shock:

A failure of circulation — pale, cold, clammy skin, rapid weak pulse, rapid breathing. Lay the casualty down, keep them warm, control bleeding/pain, and do not give food or drink. Shock is a frequent exam topic because it accompanies most serious injuries.

Burns:

Cool a thermal burn with clean water, remove constricting items before swelling, and cover with a clean non-adherent dressing. Do not break blisters or apply creams/ointments. Treat chemical burns by flushing copiously with water.

Hypothermia (treatment):

Move the casualty to shelter, remove wet clothing, insulate and rewarm gradually (warm the trunk first), handle gently (rough handling can trigger cardiac arrest), and give warm sweet drinks only if fully conscious — never alcohol.

Fractures, hypothermia, and near-drowning:

Immobilize suspected fractures; for a near-drowning casualty, start rescue breathing/CPR and treat for hypothermia. When in doubt at sea, use radio medical advice (e.g., a telemedical service) and consider evacuation.

The three atmospheric dangers:

- Oxygen deficiency — rust (oxidation), cargo, inert gas, or decomposition consumes oxygen; normal air is 20.9% O2, and below ~19.5% is unsafe. - Toxic gases — H2S, CO, hydrocarbon vapors, or cargo-specific toxins. - Flammable atmosphere — hydrocarbon vapor within its explosive range. You cannot judge any of these by sight or smell — you MUST test the atmosphere with instruments.

Entry permit and testing:

A permit-to-enter system controls every entry. Before entry: test the atmosphere from outside at several levels — oxygen content (target ~20.9%), flammable vapor (well below the lower explosive limit), and toxic gases — in that priority. Ventilate the space and re-test. The permit records the tests, the duration, and the precautions, and is signed by a responsible officer.

Precautions during entry:

Continuous or frequent re-testing and ventilation, a trained attendant stationed at the entrance maintaining communication, a rescue plan and equipment ready, lifelines/harness as needed, and approved (intrinsically safe) lighting and equipment. Personnel are briefed and the entry is logged.

Rescue — the deadly trap:

The majority of enclosed-space deaths include rescuers who rushed in without breathing apparatus and were overcome by the same atmosphere. NEVER enter to attempt a rescue without donning self-contained breathing apparatus and following the rescue plan — raise the alarm and use the prepared equipment instead.