For the purpose of clarity with regard to this article, let us classify the marine distress signals under two sections:
1) Pyrotechnic Signals and,
2) Non-Pyrotechnic Signals
Pyrotechnic Signals
These are the means capable of undergoing self-contained and self-sustained exothermic chemical reactions for the production of heat, light, gas, smoke and/or sound.
Non-Pyrotechnic Signaling
As opposed to pyrotechnic signaling, these are the methods used without the necessity of an exothermic reaction to attract attention at the time of distress. Following are the means of non pyrotechnic signaling used onboard ships:
1. Orange Signal Flag: Listed under the Annex IV of the IMO International Regulations For Preventing Collisions At Sea, this signal consists of a square flag which has above or below it a ball or any other object that resembles a ball.
2. Marker Dyes: In accordance with the Annex IV as mentioned above, a dye marker may be used for the purposes of distress signaling.
Find the marine parts you need and answers to all your marine parts questions at Raritan Engineering.
3. SOS: The universally known SOS as per the Morse Code which basically is the most widely known way to communicate distress.
4. Radio Signals: As part of the GMDSS, radio signaling is a method of communicating distress at sea. A distress alert may be sent by the Digital Selective Calling methods transmitted on the VHF channel 70 or the following MF/HF frequencies:
- 5 kHZ
- 5 kHZ
- 5 kHZ
- 6312 kHZ
- 12577 kHZ
- 5 kHZ
5. Mirrors: Better known as a Heliograph, a mirror might be used while onboard and mostly on a survival craft to reflect the sunshine towards the entity that one needs to attract the attention of.
6. Continuous sounding on the fog signaling apparatus onboard is a way to communicate distress
7. When the word “Mayday” is communicated verbally via radiotelephony, it indicates distress
8. As per the International Code of Signals (INTERCO), the flag NC indicates distress
9. Slowly and repeatedly raising and lowering arms outstretched to each side indicates distress
10. A ship to shore distress alert which is transmitted by the ship’s satellite communication system (INMARSAT) or any other mobile satellite service also termed as the ship earth station.
11. Signals transmitted by the Emergency Position Indicating Radio Beacon (EPIRB) indicate distress
12. Signals transmitted by the Search and Rescue Radar Transponder (SART) also indicate distress
The INTERCO and the IAMSAR Vol III must be read thoroughly to familiarize oneself with myriad means to communicate and assist in times of distress.
Pyrotechnic signals are visual and attract immediate attention to the casualty of the distressed vessel or persons. However, with the advancement of technology, quicker and better means of communicating distress have come about and the ship’s crew must be thorough with each and everyone of them.