Whether it is a whistle or a foghorn, the ship’s horn is one of the sound signalling devices on a ship. It broadcasts sound signals to warn of an obstacle or certain dangers such as banks or reefs. Find out in this article all you need to know about this maritime signalling instrument.
Focus on the ship whistle
The ship’s whistle is part of the ship’s horn, a maritime signalling equipment that is compulsory for ships over 12 m. This accessory is not a mouthpiece, but a fixed piece of equipment. It must comply with the sound level, frequency and range standards in force.
Concerning the use of the ship’s whistle
During navigation, a ship may change direction or stop. Be aware that these manoeuvres can last several minutes. Therefore, this vessel must inform other observable vessels of its intentions. To inform about changes of speed and manoeuvres, it is sufficient to apply the code of sound and light signals.
Every mechanically propelled vessel can broadcast these signals by means of a whistle.
- One short tone ( = E ) : “I am going to starboard” ( = E flag ) ;
- two short tones ( = I ): “I am going to port” ( = flag I ) ;
- three short tones ( = S ): “I am going astern” ( = S flag );
Each vessel may repeat the whistle signals several times during the manoeuvre.
In addition, if a vessel does not understand the intentions of another vessel, it may give a signal (minimum five short tones).
What about the technical characteristics of the ship’s whistle
A ship’s whistle or horn should have a fundamental frequency of between 70 and 700 Hz. This frequency is lower if the ship is large.
For example, a ship of more than 200 m in length should blow at a frequency of 70 to 200 Hz.
The whistle should be placed in a place where no part of the vessel obstructs the propagation of sound. The whistle must be placed as high as possible to achieve the maximum range. In addition, this regulation ensures that the sound level is kept clean while avoiding risks and dangers to passengers’ hearing aids.
All about the foghorn
As part of a ship’s horn, the foghorn is a device that emits a prolonged low-pitched sound. It is used in low visibility conditions to warn mariners of certain dangers.
In addition, every modern foghorn often emits laser beams to examine visibility. When the laser informs of low visibility, the foghorn is triggered by a computer. It continues to sound until visibility improves.
On the other hand, the sounds of the foghorns are largely low. This is because low tones are transmitted in a better condition and provide more warning.