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Commercial/Military Marine Horns & Whistles

 

IMO Requirements

What are the international requirements for marine horns (ship's whistles)?

The 1972 Intemational Regulations for Preventing Collisions at Sea ('72 COLREGS), ANNEX III, entered into force by the International Maritime Organization (IMO), specifies the technical requirements for sound signal appliances on marine vessels. Frequency range and minimum decibel level output is specified for each class of ship. The class is determined by the vessel's length. Sound pressure level intensity at a distance of one meter from the horn is stipulated, which determines the theoretical range of the horn, although the actual range will, under many conditions, be much greater than this. This information is displayed in the following table:

 
Whistle Class
 		 Length of Vessel in Meters
 		 Limits of Fundamental Frequency
 		 Minimum Sound Pressure Level Measured in 1/3 Octave Band at 1 Meter
 		 Audibility Range in Nautical Miles
 
I > 200 70-200 Hz 143 dB 2
II 75 -200 130-350 Hz 138 dB 1.5
III 20 - 75 250-700 Hz 130 dB 1
IV < 20 250-700 Hz 120 dB 0.5

Certificates of Conformity
Certificates for Kahlenberg Horns have been issued by the U.S. Coast Guard, ABS, and the British MCA, among others, confirming their compliance with the '72 COLREGS.

Installation
The '72 COLREGS also give recommendations relating to the installation of whistles with which installers and operators should be familiar.

Selection

 
Kahlenberg Whistles in Each Class

 


 
Class I Class II Class III Class IV
Vessel Length Over 200 Meters (656 Ft.) Vessel Length 75-200 Meters (246-656 Ft.) Vessel Length 20-75 Meters (65-246 Ft.) Vessel Length Under 20 Meters (65 Ft.)
S-203C
S-203CHT
KPH-130 (Electric) 		S-216C
S-216CHT
S-203C
S-203CHT
D-4A
Q-4
T-4A
KPH-130 (Electric)

S-2
S-2CV
S-2CHT
D-1
D-2
D-2CVL
T-1
T-2
T-3A
Q-3A

F-2
F-3
KDT-123
O2M
KB-20 (Electric)

S-0A
D-0A
T-0A
 

 

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last updated 4th July 2007