- Joined
- Jan 1, 2000
- RO Number
- 3238
- Messages
- 4,831
While looking for information regarding the New Orleans lightship(s), I encountered a maritime term I was unfamiliar with:
submarine bell
It was used aboard light ships to produce an identifying signal underwater.
Here is a reference to the device:
http://oceanexplorer.noaa.gov/history/readings/subsignaling/subsignaling.html
-----------
The submarine bell in use on the lightships is actuated by compressed air stored in a reservoir. The actuating wheel has projections mounted on it so that when the wheel revolves a number of strokes follow each other, the different intervals being peculiar to the different signal stations so that the captain of a ship by counting the strokes of the bell can determine what lightship is producing the sound.
In order to receive the sound, it has been found absolutely necessary to suspend the microphone in a tank of water, for this is the only method of cutting out the water noises and the noises due to machinery, etc., on board the ship, which otherwise drown out the sound of the bell.
One of these small water tanks, containing a microphone of a special type, is attached to each side of the bow inside of the ship. From each tank wires are run to a device which is called the indicator box, so arranged that by throwing the handle to one side, the starboard microphone is connected to the telephone, and throwing the handle to the other side, the port microphone is connected.
It will be obvious that once the bell is picked up, the captain has only to turn his vessel until the sound is heard with equal intensity on each side, to know that his ship is then pointing in the direction from which the sound is coming, and in this way he can take compass bearings of the nearest lightship or lighthouse fitted with a bell
----------------
Interesting.
For the most part, lightships are gone, so assume that this system is no longer used.
( It certainly is not a popular search on The Big Search Engine )
submarine bell
It was used aboard light ships to produce an identifying signal underwater.
Here is a reference to the device:
http://oceanexplorer.noaa.gov/history/readings/subsignaling/subsignaling.html
-----------
The submarine bell in use on the lightships is actuated by compressed air stored in a reservoir. The actuating wheel has projections mounted on it so that when the wheel revolves a number of strokes follow each other, the different intervals being peculiar to the different signal stations so that the captain of a ship by counting the strokes of the bell can determine what lightship is producing the sound.
In order to receive the sound, it has been found absolutely necessary to suspend the microphone in a tank of water, for this is the only method of cutting out the water noises and the noises due to machinery, etc., on board the ship, which otherwise drown out the sound of the bell.
One of these small water tanks, containing a microphone of a special type, is attached to each side of the bow inside of the ship. From each tank wires are run to a device which is called the indicator box, so arranged that by throwing the handle to one side, the starboard microphone is connected to the telephone, and throwing the handle to the other side, the port microphone is connected.
It will be obvious that once the bell is picked up, the captain has only to turn his vessel until the sound is heard with equal intensity on each side, to know that his ship is then pointing in the direction from which the sound is coming, and in this way he can take compass bearings of the nearest lightship or lighthouse fitted with a bell
----------------
Interesting.
For the most part, lightships are gone, so assume that this system is no longer used.
( It certainly is not a popular search on The Big Search Engine )