Background
The fundamental challenge of survival craft design is the requirement to deploy reliably in the worst conditions imaginable, a ship rolling heavily in heavy weather, possibly listing or trimmed, possibly on fire, possibly sinking rapidly, and then to function as habitable shelters for survivors over extended periods of time pending rescue. The mechanical reliability requirements are extreme: the launching systems must work reliably even after years of being stowed in a hostile marine environment, the lifeboats themselves must survive launching shock and rough sea exposure, and the equipment carried aboard must support survival for days in worst-case conditions. The combination of mechanical, structural, environmental, and operational requirements that the LSA Code prescribes for survival craft reflects the seriousness with which the international community treats the prevention of loss of life at sea.
Regulatory Framework
The regulatory framework for lifeboats and survival craft centres on SOLAS Chapter III (Life-Saving Appliances and Arrangements) and its supporting LSA Code, with additional requirements from various supporting instruments.
SOLAS Chapter III specifies the survival craft requirements applicable to different ship types and trades, the carriage requirements (number and capacity of survival craft per person aboard), arrangements for embarkation and launching, and operational requirements including drills and maintenance. The chapter has been substantially revised since its original adoption in 1914, with major amendments in 1948, 1960, 1974, 1983, 1996, and ongoing periodic revisions.
The International Life-Saving Appliance Code (LSA Code) is mandatory under SOLAS Chapter III and contains the detailed engineering and performance requirements for all life-saving appliances. The LSA Code covers lifeboats (rigid lifeboats of various types), liferafts (inflatable and rigid), rescue boats, marine evacuation systems (MES), launching appliances and devices, lifejackets and lifebuoys, immersion suits and thermal protective aids, and various other life-saving appliances. The Code prescribes detailed performance requirements (such as launching from a 20 degree list and 10 degree trim, propulsion speed, capsizing recovery), construction requirements (materials, dimensions, equipment carried), testing requirements, and certification.
The Code of Practice for the Evaluation, Testing and Acceptance of Prototype Novel Life-Saving Appliances (LSA Testing Code) provides standardised procedures for testing and certifying new survival craft designs that may not fall within the conventional categories.
The Polar Code (mandatory under SOLAS for ships operating in polar waters) imposes additional requirements for survival craft and equipment to provide enhanced cold-weather protection and extended survival capability in polar conditions.
The International Aeronautical and Maritime Search and Rescue (IAMSAR) Manual (jointly developed by IMO and ICAO) provides guidance on rescue operations and the use of survival craft equipment to facilitate rescue.
Flag state and class society implementations of SOLAS and the LSA Code provide certification, survey, and operational requirements for ships under their jurisdictions. Periodic surveys (annual safety surveys, intermediate surveys, special periodical surveys at 5-year intervals) verify compliance throughout the ship’s service life.
Lifeboat Types
Several distinct types of lifeboats are used on commercial ships, each suited to specific operational requirements and ship types.
Open lifeboats were the dominant lifeboat type from the 19th century through the 1970s, consisting of an open rigid hull with thwarts (seating benches), a steering gear, and either oars or a small motor for propulsion. Open lifeboats expose occupants to weather and provide no protection against fire or smoke, making them progressively unsuitable for modern shipping. Open lifeboats are now found only on older grandfathered ships and certain specialised applications. New ships built since the 1990s do not typically carry open lifeboats.
Partially enclosed lifeboats include a permanent canopy over the forward and aft sections of the hull, with collapsible canvas or fabric covers for the central section. Partially enclosed boats provide some weather protection while maintaining easy access to the propulsion and steering. They have largely been superseded by totally enclosed lifeboats but remain in service on ships built before the totally enclosed requirement.
Totally enclosed lifeboats (TELBs) feature a fully enclosed rigid superstructure that protects occupants from weather, fire, and smoke. The TELB design includes a watertight or weather-tight hull, sealed hatches for access and emergency exit, internal seating with safety harnesses, and integrated propulsion and steering. TELBs can capsize and self-right (passive self-righting through hull buoyancy distribution and superstructure design), survive immersion in burning oil or water for short periods, and provide protection in temperatures from -30 to +60 degrees Celsius. TELBs have been required for new tankers since the 1980s and for new cargo ships since 1986; they are now standard on virtually all commercial ships built since.
Free-fall lifeboats are a variant of totally enclosed lifeboats designed to be launched by free-fall from a stern launching ramp rather than by davits. The boat slides down the inclined ramp, drops free of the ship, and falls into the water with all occupants secured by safety harnesses. Free-fall systems offer rapid simultaneous launching of all occupants without the need for crew to operate complex davit systems, making them particularly suited to bulk carriers, tankers, and other large ships where rapid evacuation is critical. The launching height (typically 12 to 28 metres above water) and the impact loading on occupants and boat structure are carefully designed to keep occupant accelerations within human tolerance limits.
Lifeboats for tankers carrying flammable cargoes have additional requirements for fire protection. Self-protected lifeboats include water spray systems that wet the entire exterior of the boat to protect occupants and structure from radiant heat from burning oil. Air supply systems provide breathing air independent of outside atmosphere for limited durations, allowing the boat to traverse fire-affected sea surfaces. These features are required by SOLAS for tankers carrying flammable cargoes (oil tankers, chemical tankers, gas carriers).
Hybrid arrangements combine free-fall lifeboats for primary evacuation with davit-launched lifeboats or marine evacuation systems for secondary capability. Many modern bulk carriers and tankers feature this combination.
Liferafts
Liferafts provide secondary survival craft capability and primary capability on smaller ships. Two types of liferafts are used: inflatable liferafts and rigid liferafts.
Inflatable liferafts are by far the more common type, with the raft stowed deflated in a fibreglass canister or fabric valise. Deployment is by manual release of the canister into the sea (where automatic inflation occurs as the canister breaks open) or by automatic release through hydrostatic release units (HRUs) that release the canister when the ship sinks below 4 metres depth. Once in the water, the raft inflates within 60 seconds (per LSA Code requirement) using compressed gas (typically a CO2/nitrogen mixture) from an internal cylinder.
Inflatable liferaft construction uses heavy-duty rubberised fabric in twin-tube buoyancy chambers (with the second chamber providing redundancy if the first is damaged). The canopy is integrated with the buoyancy structure, with manually inflated arches supporting the canopy. The floor is typically inflatable or insulated to provide protection from cold water.
Liferaft capacity ranges from 6 person rafts (common on smaller vessels) to 50 person rafts (used on cruise ships and large passenger vessels). Each raft is certified by class society or recognised authority for the stated capacity, with construction tested to demonstrate stability, weight-bearing capability, and equipment provision.
Davit-launched liferafts are equipped with hoisting points for launching by davit from the embarkation deck rather than by free-fall from the stowage location. Davit-launched rafts allow occupants to embark from the ship’s side, eliminating the need for them to enter the water and climb aboard from the sea. SOLAS requires that at least 50 percent of liferaft capacity on cargo ships be davit-launched, with passenger ships requiring more.
Rigid liferafts are constructed of fibreglass or other rigid materials, with permanent (rather than inflatable) buoyancy. Rigid rafts are common on smaller commercial vessels (fishing boats, small passenger vessels) where the simpler construction provides cost advantages. They are less common on large commercial ships where the higher capacity of inflatable rafts is preferred.
Liferaft equipment, prescribed by the LSA Code, includes paddles, sea anchor, drinking water, food rations (high-energy biscuits), first aid kit, signalling devices (smoke signals, hand flares, rocket parachute flares, signalling mirror, whistle, electric torch), drinking cup, can opener, fishing equipment, repair kit (for the inflatable hull), and various other survival items. The equipment is sealed in a waterproof container within the raft, accessible to occupants once deployed.
Rescue Boats
Rescue boats are specialised boats designed for rescuing persons from the water, recovering and towing other survival craft, and supporting man-overboard recovery operations. They are not primary survival craft (rescue boats do not count toward the survival craft capacity required by SOLAS for the persons aboard) but are required as supplementary capability on most ships.
Rescue boat requirements per SOLAS Chapter III include a capacity of at least 6 persons (more on certain ship types), launching from either ship’s side at maximum speed of 5 knots (the boat must be able to clear the ship’s side at this forward speed), maximum recovery time of 5 minutes from receipt of the man-overboard alarm to recovery to the davit boat-handling position, and adequate fendering for safe operation alongside other vessels and survival craft.
Fast rescue boats (FRBs) are required on certain ship types (passenger ships, oil tankers, chemical tankers, gas carriers) and provide higher performance than standard rescue boats. FRBs achieve speeds of 25 knots or more, have powerful outboard or inboard engines, and are designed for rapid response to emergency situations. FRBs typically have crew safety harnesses to retain occupants in heavy seas at high speed.
Inflatable rescue boats and rigid-hull inflatable rescue boats (RHIBs) are common configurations. Inflatable boats use the same heavy-duty rubberised fabric as inflatable liferafts, with rigid transom and floor providing structural integrity. RHIBs use a rigid hull (fibreglass or aluminium) with inflatable upper sponsons providing additional buoyancy and impact protection. RHIBs are typically used as fast rescue boats on demanding service.
Rescue boat equipment includes propulsion (outboard or inboard engine), steering controls, fuel tank, navigation lights, search light, and safety equipment for crew (helmets, harnesses, immersion suits) and recovered persons (blankets, first aid). Some rescue boats include man-overboard recovery aids such as Jason cradles or scoop nets to facilitate recovery of unconscious or injured persons from the water.
Davits and Launching Appliances
Davits are the structural devices that suspend lifeboats and rescue boats over the side of the ship and lower them into the water during launching. Several davit types are used in marine service.
Gravity davits are the most common davit type, using gravity to lower the lifeboat into the water during launching. The lifeboat is suspended from blocks at the davit head, connected to falls (wire ropes) that wind around a winch drum. To launch, the brake is released and the lifeboat lowers under its own weight, with the winch acting as a controlled brake. Gravity davits provide reliable launching without requiring power for the lowering operation, which is essential when ship’s electrical power may be unavailable in emergency.
Pivoting gravity davits use a single horizontal pivot at the deck level, with the davit arms swinging outboard to launch position from the inboard stowed position. The lifeboat sits on chocks during sea passage and tips outboard with the davit during launching. Pivoting gravity davits are common on bulk carriers, general cargo ships, and similar workhorse vessels.
Sliding gravity davits (often called “luffing davits”) use horizontal slides at the deck level, with the davit moving outboard along the slides during launching. Sliding gravity davits provide larger outboard reach than pivoting types but are more complex mechanically. They are common on tankers, container ships, and other large vessels where greater outreach is needed for clearance from the hull.
Free-fall launching ramps are the launching devices for free-fall lifeboats, consisting of a stern-mounted inclined ramp with mechanical release. The lifeboat is loaded with all occupants, doors and hatches sealed, and the release activated. The boat slides down the ramp under gravity and free-falls into the water at the bottom of the ramp. The ramp angle (typically 30 to 35 degrees), launching height, and ramp surface design ensure safe controlled deployment.
Marine Evacuation Systems (MES) are inflatable chute or slide systems for rapid evacuation of large numbers of people from passenger ships, particularly cruise ships and large ferries. MES provides the descent path from the embarkation deck to liferafts assembled at the water surface, allowing many people to descend simultaneously. Common MES configurations include vertical chutes (people slide down a fabric tube), inclined chutes (similar to playground slides), and combinations. MES installations are characteristic of large modern passenger ships.
Davit construction is typically welded steel or aluminium, with high-strength corrosion-resistant materials throughout. Class society approval and certification covers structural design, mechanical components (winches, brakes, gears), electrical components (limit switches, controls), and maintenance accessibility.
Davit testing during construction includes proof load testing at 1.5 times the rated load (for the davit) and 1.1 times the maximum lifeboat operational weight (for the winch and falls). Periodic load testing during ship operation verifies continued capability, with class rules typically specifying test intervals of 5 years for major load testing.
Embarkation and Stowage
The arrangements for embarking persons into survival craft and the stowage of survival craft are critical to safe rapid evacuation in emergency.
Embarkation deck design provides the location where persons board lifeboats prior to launching. The embarkation deck must accommodate the muster and embarkation of all persons assigned to each lifeboat, with adequate space, lighting, communication, and access. SOLAS specifies embarkation deck location requirements (such as minimum height above the lightest sea-going draft) and access requirements.
Lifeboat stowage on the embarkation deck or directly above places lifeboats where they can be reached quickly during evacuation. Stowage arrangements include cradles or chocks supporting the lifeboat during sea passage, securing arrangements (gripes) preventing motion in heavy seas, releases that allow rapid disengagement during launching, and platforms or ladders providing crew access for maintenance.
Liferaft stowage typically uses fibreglass canisters mounted on cradles at the embarkation deck or at sponson level, with hydrostatic release units (HRUs) providing automatic release at 4 metre water depth. The HRU consists of a pressure-sensitive mechanism that severs the lashings holding the raft on its cradle when water pressure exceeds the equivalent of approximately 4 metres depth. As the ship sinks, the rafts are released and float free, automatically inflating as their lanyards pull tight against still-attached painters.
Embarkation arrangements provide the means for persons to enter lifeboats and liferafts, including embarkation ladders (rigid or flexible ladders for climbing down to a deployed survival craft), boarding boats from the embarkation deck (where the lifeboat is positioned at the embarkation deck level), or chute or slide systems (for MES installations).
Crew muster stations are predetermined locations where each person is assigned during emergency, with the crew lists, lifeboat assignments, and life-jacket arrangements all converging at the muster station. Muster lists posted throughout the ship show each person’s assigned muster station and survival craft, with regular drills ensuring familiarity.
Crew Training and Drills
Effective use of survival craft requires trained crew familiar with the equipment and competent to operate it in emergency. SOLAS Chapter III prescribes training and drill requirements.
Lifeboat drills must be conducted at intervals of not more than one month, with each drill including launching of at least one lifeboat. The drill rotates through the ship’s lifeboats so that each is launched at intervals of not more than 3 months. Drills verify launching arrangements, train crew on operational procedures, and identify any maintenance issues with the equipment.
Training of officers and crew in lifeboat operation is required during initial assignment and through periodic refresher training. STCW (Standards of Training, Certification and Watchkeeping) prescribes specific lifeboatman certification for officers responsible for survival craft operation. The lifeboatman certification requires knowledge of lifeboat construction, equipment, launching procedures, navigation by lifeboat, and survival principles.
Free-fall lifeboat training has special considerations because actual free-fall launching during routine drills imposes shock loading on the boat structure and is generally limited to less frequent intervals. Simulator training and partial drills (loading and securing without actual release) are common compensating measures.
Drills should include practical exercises in equipment use including navigation by lifeboat, signalling for rescue, equipment maintenance during prolonged drift, first aid and survival procedures, and communications including emergency radio operation. The detailed knowledge required is substantial, and crew competence is best maintained through regular practical exercise.
Equipment Carried in Survival Craft
The LSA Code prescribes the equipment that must be carried aboard each lifeboat and liferaft, ensuring that survivors have the minimum tools needed for survival, navigation, signalling, and rescue.
Navigation equipment includes a magnetic compass, charts of the area, and means for determining the boat’s position (often satellite navigation in modern installations). Lifeboats carry full navigation equipment for prolonged independent voyaging; liferafts have more limited navigation due to their drift-only operation.
Propulsion (lifeboats only) includes engine, fuel for at least 24 hours of cruising at 6 knots, fuel reserve, paddles or oars as backup, and steering gear.
Communications include emergency position indicating radio beacons (EPIRBs) with GMDSS frequencies, search and rescue transponders (SARTs), portable two-way VHF radios, and signalling devices including hand flares, smoke signals, rocket parachute flares, signalling mirror, electric torch with morse signal capability, and whistle.
Survival equipment includes drinking water (3 litres per person), food rations (high-energy biscuits sufficient for 3 days), thermal protective aids or immersion suits (in cold-weather areas), seasickness medications, first aid kit, fishing kit, knife, can opener, hatchet, and various tools.
Maintenance equipment for inflatable rafts includes patches and adhesive for repairs to the buoyancy chambers and floor, a hand pump for top-up inflation, and a sponge for bailing.
Special equipment includes sea anchors (drogues that slow drift and orient the raft into the wind), painter lines for connection to other survival craft, bailers for water removal, and various other items per LSA Code requirements.
The complete equipment list ensures that survivors have what they need to maintain themselves during the wait for rescue, communicate their distress, and assist in their own rescue when help arrives.
Maintenance and Inspection
Survival craft maintenance is critical to reliability when needed in emergency. SOLAS, the LSA Code, and class society rules establish detailed maintenance requirements.
Daily and weekly checks include visual inspection of survival craft and launching equipment for damage or deterioration, verification of stowage securing arrangements, exercising of essential controls (winch motors, davit operation), and confirmation that automatic systems (HRUs, batteries) are operational.
Monthly drills include complete launching exercises (one lifeboat per drill, all lifeboats within a 3-month cycle), practical equipment use exercises, and combined drills with other safety equipment (fire drills, abandon ship drills, communications drills).
Quarterly maintenance includes inspection of falls and other rigging, lubrication of davit components, brake inspection and adjustment, and testing of automatic launching systems.
Annual surveys by class society verify all aspects of survival craft equipment, including external visual inspection of all components, functional testing of launching systems, condition assessment of falls (wire ropes), testing of automatic release systems (HRUs, on-load release mechanisms), and review of maintenance records.
Five-year overhauls during special periodical surveys involve complete teardown of davit machinery, replacement of consumables, re-certification of pyrotechnics (which have specific shelf lives), and proof load testing of davits and falls.
Liferaft annual servicing at certified shore facilities involves complete inflation testing, equipment inventory verification and replacement of expired items, repacking, and certification renewal. Each liferaft has a certificate of service that must be presented during port state inspections and class surveys.
Pyrotechnic replacement is required when manufacturer’s expiry dates are reached, typically 36 months from manufacture. Hand flares, smoke signals, and rocket parachute flares all have limited shelf life and must be replaced before expiry.
EPIRB and SART batteries have specific service lives (typically 3 to 5 years for EPIRBs, 2 to 3 years for SARTs) and must be replaced or units replaced at expiry. Annual EPIRB testing verifies continued operability.
Specific Applications
Different ship types have characteristic survival craft arrangements matched to their operational profile and crew/passenger capacity.
Bulk carriers, tankers, and general cargo ships typically carry one totally enclosed lifeboat or free-fall lifeboat with capacity for the entire crew on each side or at the stern, plus inflatable liferafts providing additional 100 percent capacity (so total capacity is 200 percent of crew). On ships with free-fall lifeboats, the free-fall boat is typically the primary evacuation craft with liferafts providing redundancy.
Container ships have similar arrangements to bulk carriers, with consideration for the high freeboard during light loaded conditions affecting embarkation and launching.
Tankers and chemical carriers must carry self-protected lifeboats (with water spray and air supply systems) for 100 percent of crew on each side, plus liferafts for 200 percent of crew on each side, accounting for the fire risk from cargo.
Passenger ships have substantially more demanding requirements. SOLAS requires lifeboats and liferafts totalling 125 percent of total passenger and crew capacity, with at least one lifeboat on each side capable of accommodating all those assigned to embarkation stations on that side. Modern cruise ships use combinations of large totally enclosed lifeboats (capacity to 150 persons each) and large davit-launched liferafts plus marine evacuation systems for rapid deployment.
Offshore vessels, drilling rigs, and floating production units have specialised survival craft arrangements reflecting their unique operational profile. Free-fall lifeboats positioned at multiple locations around the structure provide redundancy. TEMPSC (Totally Enclosed Motor Propelled Survival Craft) is the term often used in the offshore industry for the lifeboats used.
Polar Code ships operating in polar waters carry additional cold-weather equipment including immersion suits with insulation, thermal protective aids, additional rations, and equipment for ice and snow conditions.
Future Developments
Survival craft technology continues to evolve in response to operational experience, technological advances, and changing operational profiles.
Advanced free-fall lifeboat designs incorporate impact-absorbing materials, improved seating with better occupant restraint, and enhanced thermal and weather protection. Modern free-fall boats achieve safer launches with reduced occupant accelerations.
Smart survival craft incorporate satellite communications, automated EPIRB activation, GPS tracking, and onboard sensors that provide rescue authorities with real-time data on craft location, condition, and occupants. The improved situational awareness substantially reduces rescue times.
Enhanced training using virtual reality simulators allows crew to experience realistic survival craft launching and operation scenarios without the cost and risk of actual launching. Simulator training is increasingly accepted as a supplement or partial replacement for live drills.
Liferaft improvements include longer service intervals (achieved through advanced materials and packaging), enhanced canopy designs (for better weather protection and visibility), and improved automatic deployment systems.
Polar Code requirements drive specialised cold-weather survival craft developments including extended-duration thermal protection, ice-reinforced hulls, and specialised cold-weather equipment.
Digital documentation and tracking systems replace paper certificates and manual records with electronic systems integrated with ship management software, providing better visibility of equipment status, scheduled maintenance, and compliance.
Conclusion
Lifeboats and survival craft represent the last line of defence for crew and passengers when other measures to save the ship have failed. The combination of properly designed survival craft, reliable launching systems, comprehensive equipment, trained crew, and rigorous maintenance produces the capability to abandon ship safely in worst-case scenarios. The SOLAS Chapter III and LSA Code framework, refined through more than a century of operational experience and casualty analysis, ensures that all classed merchant ships carry adequate equipment maintained to high standards. Crew members responsible for survival craft must understand the design principles, regulatory framework, operational practices, and maintenance requirements that together ensure these critical safety systems function when needed. As the maritime industry evolves through technology and changing operational profiles, survival craft are evolving with it, but the fundamental purpose, saving lives at sea, remains unchanged.
Related Calculators
- LSA Lifeboat Capacity Calculator
- Safety Lifeboat Capacity Calculator
- LSA Lifejacket Count Calculator
- Offshore Lifeboat Free-Fall Calculator
- Offshore Totally Enclosed Lifeboat Calculator
- IMO LSA Code Calculator
- Polar Code Survival Calculator
- Polar Survival Duration Calculator
Additional calculators:
Additional related wiki articles:
- Marine Pilot Ladders and Accommodation Ladders
- Marine Inert Gas Systems
- Marine Bridge Equipment and Integrated Bridge Systems
Related Wiki Articles
- SOLAS Chapter III: Life-Saving Appliances and Arrangements
- Polar Code
- SOLAS Chapter II-2: Fire Protection
References
- SOLAS Chapter III - Life-Saving Appliances and Arrangements
- IMO International Life-Saving Appliance (LSA) Code
- IMO Code of Practice for Evaluation, Testing and Acceptance of Prototype Novel Life-Saving Appliances
- Polar Code (mandatory under SOLAS for ships in polar waters)
- IAMSAR Manual (International Aeronautical and Maritime Search and Rescue Manual)