A Guide To Different Types of Alarms on Ships

A maritime emergency at sea does not come with an alarm. Still, ship emergency signals and alarms can help us tackle a crisis or avoid an emergency efficiently and effectively.

Emergency signals or alarms on a ship are installed throughout the vessel’s various systems and machinery to notify the crew about dangerous situations that can arise from different types of emergencies onboard the ship.

Emergency alarms are of the audible and visual type to ensure that a person can listen to the audible alarm when working in an area where seeing a visual alarm is not possible, and vice versa.

It is a standard practice in the international maritime industry to have an emergency alarm on the ship for a particular warning that is similar for all seagoing vessels, no matter in which seas they are sailing or to which company they belong.

Diagram of Different Alarms on Ship

This commonness helps the seafarer know and understand the type of warning/ emergency or ship emergency alarm well, and helps tackle the situation faster.

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Types of Alarms on Ships

These are the different types of emergency alarms or signals onboard a ship that are installed to give audio-visual warnings:

1) General Alarm

The general emergency alarm on the ship is recognised by 7 short ringings of the bell, followed by a long ring, or using the ship horn signal of 7 short blasts, followed by 1 long blast.

The general alarm in a ship is sounded to make the crew aware that an emergency has occurred, such as fire, collision, grounding, or a scenario that can lead to abandoning the ship, etc.

The vessel’s general alarm system activation point is located in the navigation bridge. Once the general alarm signal onboard is activated, i.e. seven short one long blasts (7 short 1 long blast), every ship crew must follow the instructions and duties listed in the muster list and proceed to the designated muster station.

Action to be taken by the crew once the ship’s general alarm is sounded:

• Proceed to the designated muster stations
• Listen to the Public Addressing (PA) system for the type of emergency (usually announced by OOW, Chief Officer or Captain) leading to the general alarm on a ship.
• Once the nature of the emergency is known, the crew member must re-group as per the Squad and take corrective action to tackle the situation as per the muster plan.

Related Reading:

• Guide to Handle Different Emergency Situations On a Ship
• Importance of Fire Drills On Ships

2) Fire Alarm on the Ship

Whenever there is a fire detected on the vessel by its crew, they should raise the alarm signal onboard the ship by pressing the nearest fire switch or by loudly and continuously shouting “FIRE FIRE FIRE”. The ship’s fire alarm signal is sounded as the continuous ringing of the ship’s electrical bell or the continuous sounding of the ship’s horn.

The fire signal must be a continuous blast of the whistle or electrical bell for not less than 10 seconds. However, in most of the vessels, the fire signal is rung continuously on the alarm bell.

Once the master decides to dismiss the crew from fire stations, the general alarm will be sounded three times, followed by three short blasts of the ship’s whistle.

Action to be taken by the crew once the ship’s fire alarm is sounded:

• Proceed to the fire station
• Confirm the location of the fire
• Perform the duty listed in the muster list as per the team assigned

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3) Man Overboard Alarm

There have been many situations when a crew member working on the ship-side or a passenger on a cruise ship fell into the water at high seas. When a man falls overboard, the man overboard alarm sound signal is activated on board the vessel.

The MOB alarm signal comprises the vessel’s internal alarm bell for 3 long rings to notify the crew onboard, along with 3 long blasts on the ship whistle to inform the other ships in the nearby vicinity.

A man overboard signal comprising light and smoke can also be mounted on the bridge, attached to the side of the lifebuoy. When thrown in the water, it will emit smoke and light to draw the ship’s crew or other ships around the vicinity.

Action to be taken by the crew once the ship’s MOB alarm is sounded:

4) Abandon Ship Alarm

When the emergency on board a ship goes out of hand, and the vessel is no longer safe for the crew on board, the signal for abandon ship is given verbally by the master to the station in charge of the crew on the ship’s Personal Addressing (PA) system.

More than six short blasts and one prolonged blast on the ship’s whistle, and the same signal on the general alarm bell is used as an abandon ship alarm or sound signal onboard the ship. However, the alarm sounded is similar to a general alarm, and everybody comes to the emergency muster station where the master or his substitute (Chief Officer) gives a verbal order to abandon the ship.

Action to be taken by the crew once Abandon ship is announced or sounded:

• Carry your lifejacket/ immersion suit to the designated muster station
• Carry any additional items (Blanket/ ration/ water, etc.) as stated under the duty in the muster list
• Avoid taking longer routes and routes going from inside the accommodation to the muster station
• Wait for the master’s order to abandon the ship

5) Navigational Alarm

In the navigation bridge, most of the navigational equipment and navigation lights are fitted with failure alarms. If any of these malfunctions, a ship alarm signal on the bridge will be sounded whose details (location, equipment affected, type of problem etc.) will be displayed on the notification screen provided on the bridge navigation panel.

Action to be taken by the crew once the navigational alarm is sounded:

• Check which equipment the alarm is concerning
• Try to locate the fault due to which the alarm is coming
• Rectify the fault or switch the standby equipment if needed

Related Reading

• What is Bridge Navigational Watch & Alarm System (BNWAS)?
• What is Integrated Bridge System (IBS) on Ships?

6) Machinery Space Alarm

The ship’s engine room is fitted with different machinery, which is continuously monitored for operation using a control and monitoring system.

The machinery in the engine room has various safety devices and alarms fitted for safe operation. If any machinery malfunctions, a standard engine room alarm is operated, and the problem can be seen in the control room alarm panel, which will display the alarm.

Action to be taken by the crew once the engine room alarm is sounded:

• Check which machinery/system the alarm is related
• Try to locate the fault due to which the alarm is coming
• Rectify the fault or switch the standby machinery if needed

Related Reading

12 Ways to Master the Engine Room Watch Keeping Procedure

7) Machinery Space CO2 Alarm

The machinery space is fitted with a CO2 fixed fire extinguishing system. The audible and visual alarm for the CO2 fixed firefighting system is entirely different from the machinery space alarm and other ship alarm signals for easy reorganisation.

The audible alarms shall be located to be audible throughout the protected space when all machinery is operating. The alarms should be distinguished from other audible alarms by adjustment of sound pressure or sound patterns.

The alarm should activate upon opening the release cabinet door, which is used to open and release the CO2 bottle banks.

Action to be taken by the crew once the navigational alarm is sounded:

8) Cargo Space CO2 Alarm

The ship’s cargo spaces are also equipped with a fixed firefighting system, which operates with a distinct alarm. The audible and visual alarm for the CO2 fixed firefighting system is entirely different from other ship alarms; the audible alarm should be distinguished from other ships’ alarms by adjusting sound pressure or sound patterns.

Action to be taken by the crew once the navigational alarm is sounded:

• Take a headcount of the crew
• Ensure the cargo hold is sealed and no crew is inside
• Ensure all the ventilation systems for the cargo hold are shut

Related Read:

 8 Mistakes You Should Never Make While Handling CO2 Fire Fighting System

9) Ship Security Alarm System

As per the SOLAS Chapter XI regulation XI-2/5, all ships shall be provided with a ship security alert system. The Ship Security Alarm system (SSAS) is silently sounded in a pirate attack emergency. When the SSAS is activated, no alarm is sounded on board the ship, nor are alerts sent to other vessels in the vicinity. Instead, this signal notifies different coastal authorities or competent authorities whose proximity to the ship is presently operating via a global satellite system to inform them about the piracy.

Different Alarm signals of the vessel are clearly described in the muster list, along with the actions to be taken, so that all crew members can perform their duties promptly in an actual emergency.

It is of extreme importance that a seafarer knows the different types of alarms in a ship and recognises which emergency they represent.

Listen to Real Sound Of Different Types of Alarms on Ships:

Related Read: 

• The ISPS Code For Ships – An Essential Quick Guide
• What is Bridge Navigational Watch Alarm System (BNWAS)?
• Bridge of a Ship: Design And Layout
• Different Entries To Be Made In Bridge Log Book of The Ship
• Sprinkler System: Automatic Fire Detection, Alarm and Extinguishing System on Ship

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About Author

Raunek Kantharia is a marine engineer turned maritime writer and entrepreneur. After a brief stint at the sea, he founded Marine Insight in 2010. Apart from managing Marine Insight, he also writes for a number of maritime magazines and websites.

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