Search and Rescue (SAR) Operations for Mariners

1. Duty to Render Assistance — COLREGS Rule 33 and 46 USC 2304

The Legal Obligation

The duty to render assistance to persons in distress at sea is both an international and domestic legal obligation. 46 USC 2304 — the primary U.S. statute — mandates that the master of any vessel render assistance to any individual found at sea in danger of being lost, as long as doing so does not seriously endanger the vessel, crew, or passengers. Failure to comply is a federal crime punishable by a fine of up to $1,000 and/or imprisonment for up to two years.

COLREGS Rule 33 — incorporated into U.S. law through the Inland Navigation Rules — mirrors this obligation internationally. It applies to every vessel on the high seas and in waters connected therewith, requiring masters to render assistance to persons in distress if it can be done without serious danger to the ship and those on board.

Scope and Limits

The obligation applies regardless of nationality, the cause of the distress, or whether the vessel is commercial or recreational. A master may decline assistance only if rendering it would create a serious danger — not merely inconvenience or delay. Key limits recognized by law include:

• Another vessel is already rendering effective assistance and no additional help is needed
• The vessel in distress refuses assistance
• Rendering assistance would place the rescuing vessel in immediate peril

A master who renders assistance and rescues survivors must deliver them to a place of safety. SOLAS Chapter V, Regulation 33 reinforces this, stating that the master has no discretion once the duty is triggered — rescued persons must be landed at the next port of call or another place of safety, not simply transferred at sea unless conditions require it.

Commercial Vessel Responsibilities

Commercial vessel operators have enhanced obligations. Under SOLAS, vessels on international voyages must proceed to the assistance of persons in distress when informed of their need for help. They must also maintain a distress watch on Channel 16 (VHF) and DSC Channel 70 at all times. GMDSS-equipped vessels — those over 300 GT on international voyages — have specific equipment requirements to ensure they can both detect and respond to distress situations.

2. Distress Communication — Mayday, Pan-Pan, and Securite

The Three Radio Urgency Signals

International maritime radio procedures use three spoken prefix words to indicate the urgency level of a transmission. Each is spoken three times to open the call. Understanding the distinction is critical for both the exam and real operations.

Mayday Call Procedure — Voice (Channel 16)

A voice Mayday follows a standardized format. Speaking slowly and clearly is critical — garbled or rushed transmissions waste time during an emergency.

If there is no response after one minute, repeat the call. After three unsuccessful attempts on Channel 16, try 2182 kHz (SSB) if available. Maintain a radio watch after transmitting.

DSC Distress Alert — Digital Selective Calling

Modern VHF radios with DSC capability transmit a digital distress alert on Channel 70 before the voice Mayday. DSC Class D radios (standard on most recreational vessels) transmit the vessel MMSI number and, if connected to GPS, automatically include position and time. The USCG and nearby vessels with DSC receive the alert instantly.

The correct sequence for a DSC-equipped vessel is:

1. Lift the protective cover on the DSC distress button
2. Press and hold the DISTRESS button for 3-5 seconds until confirmed
3. The radio automatically transmits on Channel 70 and switches to Channel 16
4. Make the voice Mayday on Channel 16 immediately after the DSC alert

Canceling a False Mayday

If a Mayday is transmitted in error, cancel it immediately:

Also contact the nearest Coast Guard station directly by phone if possible. Failure to cancel false alerts wastes significant USCG resources and can result in civil penalties.

3. SAR Equipment — EPIRB, SART, and PLBs

EPIRB — Emergency Position Indicating Radio Beacon

An EPIRB transmits a 406 MHz distress signal that is received and processed by the Cospas-Sarsat satellite network. The signal encodes a unique 15-digit hex ID linked to the vessel through NOAA registration. When activated, Cospas-Sarsat determines position (via onboard GPS or Doppler calculations) and relays the alert to the nearest Local User Terminal, which forwards it to a Mission Control Center, which notifies the USCG.

All EPIRBs must be registered with NOAA. Registration is free and links the beacon ID to vessel name, owner contact, and emergency contacts. An unregistered EPIRB still triggers a response but USCG has no vessel information, slowing rescue. Battery and HRU expiration dates must be current — expired beacons are a USCG violation.

EPIRB self-test: Press and hold the test button. Perform tests only during the first 5 minutes of any UTC hour — Cospas-Sarsat recognizes this window as test mode. Testing outside this window can trigger a false alert and USCG response.

SART — Search and Rescue Transponder

A SART is a radar transponder used in survival craft after abandoning ship. When interrogated by an X-band (9 GHz) radar, the SART responds with a signal that appears as a series of 12 equally-spaced dots on the rescuer's PPI radar display, extending outward from the SART's position. The innermost dot is the SART's actual location.

• Detection range: approximately 5 nm by ship radar; up to 40 nm by aircraft radar
• At less than 1 nm: dots expand into arcs or concentric rings
• Battery life: minimum 96 hours on standby, 8 hours while transmitting
• Frequency: responds to X-band radar (9 GHz); S-band radar will NOT trigger a SART

AIS-SART is a newer variant that transmits AIS distress messages rather than radar responses, appearing on AIS displays as a distress target. Both types may be carried to maximize detection by different types of searching assets.

PLB — Personal Locator Beacon

A Personal Locator Beacon (PLB) is a smaller, personal-use device that operates on the same 406 MHz Cospas-Sarsat system as an EPIRB. Key differences from an EPIRB:

• Registered to a person, not a vessel — stays with the individual
• Manual activation only — no float-free capability
• Minimum battery life: 24 hours (vs. 48 hours for EPIRB)
• Regulated by the FCC in the U.S. — no license required to operate
• Registered with NOAA, same as EPIRBs
• Does NOT replace the EPIRB requirement for commercial vessels

4. USCG SAR Coordination and On-Scene Coordinator

How USCG Coordinates SAR

The United States Coast Guard serves as the primary SAR authority in U.S. waters and in the SRR (Search and Rescue Region) assigned to the U.S. under SOLAS. The USCG operates SAR from two levels:

• SAR Mission Coordinator (SMC): The overall coordinator, typically the USCG District or Sector Operations Center ashore. The SMC receives the initial distress notification, evaluates the situation, allocates SAR resources, and directs the overall response.
• On-Scene Coordinator (OSC): The vessel or aircraft designated by the SMC to coordinate search efforts on scene. The OSC receives search assignments from the SMC and directs all assets physically present at the scene.

On-Scene Coordinator Duties

The OSC role may be assigned to any available vessel — commercial, naval, or recreational. The first vessel to arrive on scene typically assumes OSC duties until a more capable asset arrives. OSC responsibilities include:

• Establishing and maintaining communications with the SMC on established SAR frequencies
• Coordinating the movements of all vessels and aircraft on scene
• Assigning search tracks and sectors to each asset
• Updating drift calculations as conditions change
• Maintaining the SAR log — times, positions, search tracks covered, results
• Reporting search results to the SMC and requesting additional resources as needed
• Coordinating medical care or evacuation if survivors are found

SAR Communications

During a SAR operation, specific radio channels are used to keep communications organized:

• VHF Channel 16: International distress, safety, and calling channel. All vessels must monitor 16 at all times underway. Initial distress calls and USCG broadcasts go here.
• VHF Channel 22A: USCG working channel in the U.S. After initial contact on 16, USCG typically directs vessels to switch to 22A for working communications.
• VHF Channel 70: DSC digital calling — voice communications are prohibited on this channel.
• 2182 kHz (SSB): International distress frequency for medium-frequency SSB radio, monitored as a backup.

5. SAR Search Patterns and Drift Calculations

Determining the Datum

Before selecting a search pattern, the SAR coordinator must establish the datum — the most probable position of the search object at the time searching begins. Datum is calculated from the Last Known Position (LKP) plus estimated drift from the time of distress to the start of search.

Drift has two components: leeway (wind-driven drift, typically 3-5% of wind speed for a small boat) and set and drift(current-driven movement, taken from current tables or observed data). Both are applied as vectors to the LKP over the elapsed time. The resulting position is datum. A search area (called the SRU — Search and Rescue Unit) is then drawn around datum based on the uncertainty in the datum calculation.

Expanding Square Search (VS Pattern)

Used when datum is well-established and the search area is relatively small. The searching vessel starts at datum and makes a series of right-angle turns, expanding outward in a square spiral. Track spacing equals the sweep width of the searching unit. The pattern provides high-probability coverage of the area immediately surrounding datum.

• Start at datum, proceed a defined distance, turn 90 degrees right
• After each two legs, increase the leg length by one track spacing
• Best for: high datum confidence, small search area, single vessel

Sector Search (Rotating Sector)

Used when datum is highly reliable and the search object is believed to be in a small well-defined area. The vessel proceeds from datum outward on one track, returns to datum, turns 120 degrees, proceeds outward on the next track, returns again, and repeats. Three outward legs complete one full sector search, each separated by 120 degrees. This provides very thorough coverage of the area immediately around datum.

Parallel Track Search (Track Line Pattern)

Used when datum is less certain and the search area is large. Multiple vessels or one vessel covers the area by running parallel tracks spaced evenly apart (track spacing = sweep width). The pattern provides uniform coverage across a large area and is efficient for wide searches. Best suited for multiple assets working together.

• Tracks are run parallel, spaced by track spacing (S)
• Coverage Factor (C) = Sweep Width (W) divided by Track Spacing (S)
• Best for: large areas, poor datum confidence, multiple search assets

Creeping Line Search

A variation of the parallel track search in which the tracks advance in one direction (creep) rather than doubling back through the same area. Used when the search object is believed to be drifting in a consistent direction — the search area advances in the same direction as the drift, reducing double-coverage of searched water. Particularly useful in open ocean searches with a known current or wind direction.

Drift Calculation Basics

Drift calculation answers the question: "Where is the search object now, given that it was last seen at position X at time T?" The calculation uses:

• Leeway: Wind-driven movement of the vessel relative to the water. Expressed as a percentage of wind speed (typically 3-5% for a small open boat). A 20-knot wind produces roughly 0.6-1.0 knot of leeway drift downwind.
• Current (Set and Drift): The direction (set) and speed (drift) of water movement from tide or ocean currents, obtained from current tables, USCG broadcasts, or NOAA predictions.
• Time Elapsed: Hours since the LKP. Multiply leeway speed and current speed by elapsed time to get distance traveled in each direction.

The two drift vectors (leeway and current) are added vectorially to produce a total drift from the LKP. The result is the datum. The USCG uses the SAROPS (Search and Rescue Optimal Planning System) computer model for operational searches, but the exam tests the conceptual understanding of drift components.

6. Helicopter Rescue and Rescue Swimmer Operations

Vessel Responsibilities During Helicopter Rescue

When a USCG helicopter is conducting a rescue from your vessel, the master's responsibilities are significant. Proper coordination prevents injury to crew, swimmers, and aircrews.

• Establish radio contact: Contact the helicopter on VHF Channel 16 or as directed by the USCG. They will give approach and procedure instructions.
• Steady course and speed: Maintain a steady course — typically into the wind or as directed by the aircrew — so the helicopter can hover in a stable position relative to the vessel.
• Clear the deck: Remove all antennas, rigging, and other obstructions from the designated hoist area. Secure or remove any loose gear that could be blown by rotor wash.
• Ground the rescue device: Allow the hoist hook or rescue basket to touch the deck or water before touching it with your hands. The static electricity buildup from a hovering helicopter can deliver a severe shock.
• Do not secure the hoist cable: Never tie or secure the hoist cable to the vessel. If the helicopter must move suddenly, a secured cable can capsize the vessel or crash the aircraft.
• Illumination: At night, illuminate the hoist area with deck lights but avoid shining lights directly at the helicopter — it will blind the pilots.

USCG Rescue Swimmer Operations

USCG Aviation Survival Technicians (ASTs), commonly called rescue swimmers, deploy from helicopters to assist distressed persons in the water or on vessels where direct hoist is not possible. Key points for mariners:

• The rescue swimmer is in command of the rescue once in the water — follow their instructions
• Do not swim toward the helicopter or attempt to grab the hoist cable in the air
• If multiple survivors are in the water, the rescue swimmer will determine the order of rescue — do not fight for priority
• Panicked survivors can be sedated by the rescue swimmer if necessary for safety
• Once in the rescue basket or direct hoist harness, cross arms over chest and stay still

Hoist Devices

USCG helicopters use several hoist devices depending on the situation:

• Rescue Basket (Stokes Litter): An open metal basket into which an injured or incapacitated survivor can be loaded. Used when the survivor cannot assist in their own rescue.
• Billy Pugh Net: A circular net device that multiple survivors can cling to for simultaneous hoist. Less commonly used today.
• Rescue Strop (Horse Collar): A loop harness placed under the survivor's arms and behind the back. Requires the survivor to be conscious and able to follow instructions.
• Direct Hoist with Rescue Swimmer: The swimmer attaches to the survivor using a harness system and both are hoisted together.

7. Abandon Ship and Life Raft Deployment

When to Abandon Ship

The decision to abandon ship is the master's responsibility and should not be made prematurely. The general rule is: stay with the vessel as long as it is safer than the water. A vessel, even a disabled or sinking one, is easier to spot by searchers than persons in the water. Abandon ship only when:

• The vessel is sinking and further delay will prevent safe abandonment
• Fire cannot be controlled and is threatening the survival of the crew
• The vessel is breaking apart and cannot support the crew
• A hazardous material situation makes remaining aboard more dangerous than the water

Do NOT abandon ship because the vessel is disabled, out of fuel, or taking on water that can be controlled. These situations warrant a Pan-Pan or Mayday call and waiting for rescue — not abandonment.

Pre-Abandonment Actions

Before abandoning, complete as many of these steps as conditions allow:

1. Transmit a Mayday on VHF Channel 16 with DSC distress alert on Channel 70
2. Activate the EPIRB — either manually or confirm it will float-free
3. Sound the abandon ship alarm (seven or more short blasts followed by one long blast)
4. All crew dons survival suits (immersion suits) and life jackets
5. Assemble crew at muster stations
6. Take the SART, PLBs, portable VHF radio, flares, water, and first aid kit if possible
7. Prepare and launch life rafts

Life Raft Deployment Procedure

Inflatable life rafts are either stored in a cradle with a hydrostatic release (Category I vessels) or in a valise/canister that must be manually deployed. For manual deployment:

1. Carry the raft container to the leeward (downwind/downwave) side of the vessel
2. Secure the end of the painter line to a strong point on the vessel
3. Throw the canister or valise overboard — do not open it first
4. Pull the painter line sharply to trigger CO2 inflation (approximately 30 seconds)
5. If the raft inflates upside-down, right it using the righting straps on the hull
6. Board the raft — use the boarding ladder if available; enter feet-first from the water if necessary
7. Assist other survivors aboard before cutting the painter line
8. Cut the painter only when the vessel is about to sink or create suction — a painter kept taut keeps the raft close for remaining survivors
9. Once clear, deploy the sea anchor to reduce drift and maintain position near the LKP

Life Raft Survival Priorities

Once in the life raft, survival priorities in order are:

• Activate signaling devices: EPIRB (if not already active), SART, signal mirror, flares. Begin signaling immediately — the best chance of rescue is in the first hours.
• Treat injuries: Hypothermia is the primary killer. Minimize exposure by closing the raft canopy, keeping survivors out of the water in the raft, and huddling for warmth.
• Water before food: Ration fresh water immediately. Do NOT drink seawater — it accelerates dehydration. Most rafts carry emergency desalination equipment or ration packs.
• Maintain watch: Station a lookout at all times for aircraft and vessels. Prepare signals before potential rescuers are overhead — reaction time is measured in seconds.

Frequently Asked Questions

Key Terms Reference