[FAQ] What are the Different Types of Alarms on Ships?


Ship emergency signals and alarms can help us tackle a crisis or avoid an emergency efficiently and in the right way.

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

Types of Alarms on Ships

These are the different types of emergency alarms or signal onboard ship that is 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 general alarm system activation point is located in the navigation bridge. 

2) Fire Alarm on the Ship:

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 ships 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

3) Man Overboard Alarm:

When a man falls overboard, the man overboard alarm sound signal is activated on the ship.

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 in the bridge, attached by the side of the lifebuoy. When thrown in the water, it will emit smoke and light to draw the ship’s crew or other ship around the vicinity.

4) Abandon Ship Alarm:

When the emergency on board ship goes out of hand, and the ship is no longer safe for the crew on board ship, 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 ship. 

However, the alarm sounded similar to a general alarm; 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 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 to
  • Try to locate the fault due to which the alarm is coming
  • Rectify the fault or switch the standby equipment if needed

6) Machinery Space Alarm:

The ship’s engine room is fitted with different machinery, which is continuously monitored for its 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 common 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 concerning to
  • Try to locate the fault due to which the alarm is coming
  • Rectify the fault or switch the standby machinery if needed

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

8) Cargo Space CO2 Alarm:

The ship’s cargo spaces are also fitted with a fixed firefighting system that has a different alarm when operated. 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 alarms in a ship 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 cargo hold are shut

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 silent sounded in a pirate attack emergency. 

When the SSAS is activated, no alarm is sounded on board the ship nor alert other vessels in the vicinity. Instead, this signal notifies different coastal authorities or competent authorities, whose proximity the ship is presently operating via a global satellite system to inform about the piracy.

Did you subscribe to our daily newsletter?

It’s Free! Click here to Subscribe!

Source: marine insight 


  1. Muchas gracias por la info, muy completa y entendible
    Tengo una duda si me pudieran ayudar, en que parte del SOLAS O FSS O LSA aparece el tipo de alarma qué se debe emitir de forma manual para cada siniestro (abandono, incendio, hombre al agua, etc) de ante mano muchas gracias