- Amie Ritchie
Every second counts when someone goes overboard. That is not a figure of speech. It is a clinical fact. Whether you run a commercial fishing vessel, a crew transfer vessel servicing offshore wind turbines, or a superyacht, having the right Man Overboard Recovery Systems in place is both a legal requirement and a basic obligation to the people who work on your vessel. This guide covers everything from the physiology of cold water immersion to the latest SOLAS-compliant equipment, with enough regulatory detail to inform procurement decisions and enough practical context to shape your next drill.
What is MOB Recovery? The Definition and the Physiology Behind It
Man Overboard Recovery is the full sequence of actions, equipment, and procedures used to locate, reach, and retrieve a person who has entered the water from a vessel. The definition is simple. The event itself rarely is.
When a person hits cold water, the body responds in ways that kill people before help can arrive. Cold Water Shock sets in within the first three minutes. It causes involuntary gasping, uncontrolled hyperventilation, and in the worst cases cardiac arrest. Experienced swimmers have drowned in this phase because the body’s reflexes simply overpower conscious effort. The water does not have to be arctic. In North Sea or North Atlantic conditions, water temperatures are cold enough to trigger cold water shock even in summer.
What catches many operators off guard is a separate and equally dangerous phenomenon called Circum-rescue Collapse. This is when a casualty who appeared stable suddenly deteriorates during or immediately after being brought out of the water. The mechanism is well understood: vertical recovery forces blood away from the core, dropping blood pressure sharply. It has killed people who were conscious and communicating moments before being lifted. This is precisely why Horizontal Recovery Systems have become the clinical standard for incapacitated casualties. Recovering someone flat, parallel to the waterline, avoids the blood pressure shift that a vertical lift causes. Understanding this physiology is not box-ticking. It directly determines which Marine Life-Saving Appliances (LSA) are actually fit for purpose on your vessel.
The Three Pillars of a Successful Rescue
Every competent MOB response plan is built on three sequential phases. A failure at any one of them makes the rest irrelevant.
Pillar 1: Locate
You cannot rescue someone you cannot find. Sounds obvious, right? But in poor visibility, at night, or in a sea state above two metres, a person in the water becomes invisible within seconds of going over the side.
Modern Automatic Identification System (AIS) Beacons have fundamentally changed what is possible here. When a crew member wearing an AIS MOB device enters the water, the beacon activates automatically and starts broadcasting the casualty’s GPS coordinates on the dedicated AIS frequencies (161.975 MHz and 162.025 MHz). Those coordinates appear on the AIS displays of every equipped vessel in the area and on your own bridge immediately. Class M AIS MOB Devices are built specifically for this role, with transmission protocols designed so they are not filtered out by vessel traffic service software.
Personal Locator Beacons (PLBs) add a different and complementary capability. Where an AIS beacon talks to vessels nearby, a PLB registered with the relevant national authority reaches the GMDSS (Global Maritime Distress and Safety System) network via Cospas-Sarsat satellites, alerting SAR coordination centres regardless of how far from other shipping you are. In open-ocean passages, a PLB may be the only technology that gets rescuers moving in time.
The question of what is the difference between AIS and PLB for MOB comes up constantly among operators specifying equipment. The practical distinction is this: AIS gets a fast response from nearby vessels, while a PLB gets a coordinated response from national SAR authorities. In coastal or busy traffic corridors, AIS is faster and more direct. In deep-water or remote operations, a PLB is fail-safe. For commercial operations where the risk is genuinely high, a device that integrates both technologies is the sensible choice.
DSC (Digital Selective Calling) rounds out the locate capability. Built into GMDSS-compliant VHF radios, DSC lets a crew member broadcast an MOB alert on Channel 70 with the vessel’s MMSI number and GPS position. Every DSC-capable station within VHF range receives it. Getting crew to the point where activating DSC is a reflex response to an MOB alarm should be part of every safety management system, not an afterthought.
Pillar 2: Reach
Once you know where the casualty is, you need to get to them quickly and safely. Fast Rescue Craft (FRC) Recovery Systems are mandatory on many commercial vessel classes under SOLAS, and for good reason. An FRC can manoeuvre close to a casualty in ways a large vessel cannot, and the speed of deployment genuinely affects outcomes. FRC davits, launch systems, and recovery hooks need to be maintained to manufacturer specification and tested on a regular schedule, not just when a Port State Control inspection is imminent.
Vessels operating in Offshore Wind Farm environments face a specific reaching problem. Turbine foundations, mooring lines, and restricted manoeuvring zones can all sit between the vessel and the casualty. Offshore Wind Farm Safety Equipment has developed into a distinct product category to address this, covering compact rescue sleds, throw bag specifications for industrial sea states, and deck-mounted recovery systems designed for the physical geometry of CTV operations.
Pillar 3: Retrieve
Retrieval has seen more engineering attention in the last ten years than in the previous fifty. The reason is straightforward: traditional methods do not work for unconscious casualties. Cargo nets, Jacob’s ladders, and rescue strops all require the casualty to hold on, pull themselves up, or at minimum cooperate with the process. A hypothermic or unconscious person cannot do any of those things.
Horizontal Recovery Systems were developed specifically to solve this. They deploy as a rigid or semi-rigid rescue platform that slides under the casualty at the waterline and hoists them horizontally to deck level. The hydrostatic blood pressure shift that causes Circum-rescue Collapse does not occur because the casualty is never vertical during the process. For any Commercial Vessel Crew Recovery Solutions operating in challenging sea states, this is not a premium specification. It is the baseline of responsible procurement.
The medical evidence is unambiguous. The best way to recover an unconscious person from the water is horizontal, with minimum exertion from the casualty, keeping them supine throughout. Any procedure that departs from this raises the risk of Circum-rescue Collapse.
Essential MOB Recovery Equipment and Systems
A properly equipped vessel carries a layered set of MOB Retrieval Equipment, with each piece doing a specific job within the Locate-Reach-Retrieve structure.
Immersion Suits and Thermal Protective Aids (TPAs) buy time. They extend the casualty’s survival window by slowing heat loss, giving the locate and reach phases a better chance of succeeding. SOLAS-approved suits must meet insulation and buoyancy minimums under MSC.1/Circ.1047.
MOB Marker Buoys, including the horseshoe buoy, smoke signal, and light marker, are not glamorous technology, but they serve a critical function. When someone goes over the side, throwing a marker buoy immediately gives the bridge a visual reference point for the casualty’s last known position while the vessel is brought around. Do not underestimate them.
Recovery Davits and Cranes with Lloyd’s Register Type Approval give procurement teams and operators structural confidence that the lifting equipment will hold under load at a critical moment. Lloyd’s Register Type Approval is one of the most widely respected certification marks in commercial shipping. When specifying SOLAS Approved MOB Recovery Gear, treating Lloyd’s Register approval as a minimum threshold rather than a nice-to-have is sound policy.
For operations in hazardous areas, including petroleum platforms, chemical tankers, and LNG carriers, standard beacon rules do not apply. Ordinary electronic MOB devices can act as ignition sources in explosive atmospheres. ATEX Zone 1 Man Overboard Beacons are specifically engineered to prevent spark generation and are the only appropriate option in environments where flammable gases may be present at deck or water level. Using a non-ATEX device in a Zone 1 environment is a serious safety failure, not a minor oversight.
International Maritime Regulations: SOLAS and IMO Requirements
Getting the regulatory picture right matters for operators, safety managers, and procurement teams alike.
SOLAS (Safety of Life at Sea) is the core framework. Chapter III sets out life-saving appliance requirements for vessels on international voyages above defined gross tonnage thresholds. Operators often ask how many MOB recovery systems are required on a commercial vessel. There is no single universal number because the answer depends on vessel type, trading area, and gross tonnage. What SOLAS Chapter III, Regulation 17 does make clear is that all vessels must carry MOB recovery equipment capable of retrieving an incapacitated person from the water without any effort from the casualty themselves. That requirement alone rules out Jacob’s ladders and cargo nets as a primary recovery method.
IMO Regulation II-1/3-13 is the standard that demands attention right now. It comes into force under the 2026 SOLAS amendments and introduces new requirements for lifting appliances and recovery equipment on new passenger ships and high-risk commercial vessels. For any vessel currently under construction or going through a significant refit in 2025 or 2026, this regulation affects purchasing decisions directly. It is the most substantial revision to LSA lifting standards in over a decade.
MSC.1/Circ.1182, the IMO’s Guide for Recovery of Persons from the Water, sits alongside the hard regulations as the practical operational reference. It sets out recommended procedures for vessel approach, casualty handling, and equipment deployment. Importantly, it has been updated to reflect current medical understanding of Circum-rescue Collapse and to incorporate guidance on horizontal recovery techniques. Safety managers should keep a copy accessible and use it as the benchmark against which drills are designed.
Industry-Specific Safety Protocols
Risk profiles differ significantly across sectors, and the equipment choices that make sense for one type of operation can be poorly suited to another.
Offshore Wind Farm Operations are one of the highest-growth areas of commercial maritime risk at the moment. Technicians transferring between crew transfer vessels and turbine foundations are particularly exposed. Vessel motion, ladder transfers, and proximity to mechanical equipment all contribute to a heightened MOB risk. The industry has largely settled on mandatory integrated AIS/PLB wearables for all personnel during transfer operations, combined with vessel-mounted thermal imaging cameras for night recovery situations.
Commercial Fishing Vessels operate in conditions that would shut down most other maritime sectors. Deep-loaded vessels in heavy weather, high freeboard, entanglement risks from gear and lines, and often very small crews working punishing watch patterns. These factors combine in ways that make standard recovery procedures unworkable. Recovery systems for commercial fishing need to function with one or two crew members in high sea states and extreme heel angles. That operational reality has pushed development of self-deploying MOB platforms that do not rely on having a full deck crew available.
Superyacht Operations present a different kind of challenge. The crew may be highly professional, but guests often have no maritime training at all, no awareness of cold water physiology, and may be in formal clothing with no preparation for an immersion event. MOB recovery systems on superyachts need to be simple enough for a crew member of average fitness to operate under pressure, and robust enough to handle a casualty with no instinct for self-preservation during recovery.
Training and Drill Best Practices
The best equipment on the market provides no protection on a vessel where nobody knows how to use it properly under pressure. Every Man Overboard Recovery System needs a genuine training programme and a drill cycle that tests realistic scenarios.
The STCW framework mandates that commercial seafarers demonstrate practical proficiency in MOB recovery, covering immersion suit donning, rescue craft deployment, and full recovery evolutions. Beyond minimum compliance, operators should be running live MOB drills at intervals no greater than three months. Using a weighted mannequin that approximates the dead weight of an incapacitated adult makes these drills genuinely useful rather than performative.
After every drill, debrief against three specific time metrics: time-to-locate (from the MOB alarm to visual confirmation of the casualty), time-to-reach (from visual confirmation to the recovery craft arriving alongside), and time-to-retrieve (from arrival to the casualty secured on deck). These numbers, measured against the benchmarks in MSC.1/Circ.1182, give an honest picture of where the gaps are. Drills that produce no measurable data are very hard to improve on.
Frequently Asked Questions
How does an AIS MOB beacon work?
When it activates, either manually or automatically on water immersion, the beacon transmits a distress signal on the VHF AIS frequencies (161.975 MHz and 162.025 MHz). That signal carries the casualty’s unique MMSI code, their GPS coordinates, and a timestamp. Every AIS-equipped vessel and shore station within VHF range picks it up and displays the position on screen, allowing an immediate course correction towards the casualty.
What is the difference between AIS and PLB for MOB?
An AIS beacon broadcasts directly to nearby vessels on VHF. A PLB sends a signal via satellite to SAR coordination authorities. AIS is faster for vessels in the area to respond to. A PLB works regardless of how far you are from other shipping. The two technologies address different scenarios, which is why many commercial operators now specify devices that carry both in a single unit.
How many MOB recovery systems are required on a commercial vessel?
It varies by vessel class, flag state, and trading area. SOLAS Chapter III sets the minimum floor: at least one system capable of recovering an incapacitated person without any effort from the casualty. Many flag states and class societies require additional systems, including dedicated FRC davits, for vessels above certain gross tonnage thresholds or operating in specified sea areas.
What is the best way to recover an unconscious person from the water?
Always horizontal. Vertical recovery forces blood away from the core and can trigger Circum-rescue Collapse in someone who was stable moments before. Use a horizontal recovery system, keep the casualty’s exertion at zero, and maintain a supine position from the waterline to the deck. Once on board, apply gentle external warming and avoid rubbing the limbs, which can drive cold blood from the extremities to the core.
Conclusion
A man overboard event does not have to end in a fatality. With the right Man Overboard Recovery Systems, equipment that meets current SOLAS standards, and a crew that drills realistically, the odds shift considerably in the casualty’s favour. The regulatory picture is tightening. IMO Regulation II-1/3-13 will raise the bar for lifting appliances and recovery equipment across commercial shipping from 2026, and the technology available to operators today is significantly better than it was a decade ago.
Get the gear right, train your crew properly, and measure your drills against the benchmarks in MSC.1/Circ.1182. The sea leaves very little margin for improvisation. The planning and investment you put in before an incident are the only things that determine what happens during one.