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A Fathometer is used in ocean sounding when the depth of water is considerably deep and keeps a continuous and precise record of the depth of water under the boat or ship on which it is placed. It is an echo-sounding device in which water depths are determined by measuring the time it takes for vibrations produced by sound waves to travel from a location near the top of the water to the bottom and back. Depending on the kind of water being utilised, it is calibrated to read depth in line with the velocity of sound in that water. A fathometer may either visually represent the depth of the water or graphically indicate the depth of the water on a roll that is continually rotating and can produce a virtual profile of that water body. The fathometer meaning is derived from the word fathom. Fathom is a unit of water depth. Herbert Grove Dorsey invented and patented the first practical fathometer in 1928.
Working of fathometer
Fathometer working is quite simple and accurate compared to older methods of distance measuring of water bodies like the lead lines. A fathometer contains the following parts:
1. Transmitting and receiving oscillators ( for sending and receiving the sound waves )
2. Recorder unit ( for the recording of data)
3. Transmitter / Power unit. (power supply)
The distance between the signal’s leaving pulse and its return is calculated by multiplying half of the time between the signal’s outgoing pulse and its return by the sound speed in the water, roughly 1.5 kilometres per second. When using echo-sounding for precise applications such as hydrography, it is necessary to measure the sound speed, which is commonly accomplished by submerging a sound velocity probe into the water. Echo sounding is a special-purpose use of sonar that is used to find the bottom of any water bodies.
m. If the velocity of sound in water is v and the time interval between the transmitter and receiver is t, the depth h is given by,
h = ½ vt
The Fessenden Fathometer was one of the earliest commercial echo- machines, and it made use of the Fessenden oscillator to create sound waves. Submarine Signal Company fitted this for the first time aboard the M&M liner S.S. Berkshire in 1924.
The fathometer is more accurate because it obtains a sounding that is exactly vertical. The vessel’s speed causes it to diverge significantly from the vertical. The precision of 7.5 cm is possible in ports and harbours when the water is at normal levels and conditions. When there is a strong current, and the weather is not conducive to taking soundings with the lead line, a fathometer may be employed (an Old device to measure the depth of water). The fathometer has a higher sensitivity than the lead line.
Uses of fathometer
Fathometer echo sounding is a technique that is often employed in fishing. Variations in elevation are often associated with areas where fish gather. In addition, schools of fish will be recorded. Fishfinder is an echo-sounding instrument, similar to a fathometer, that is used by both recreational and commercial fishermen to locate fish and other marine life.
This fathometer is installed on almost all ships and submarines in order to get an idea of the depth of water bodies and the morphology of rocks and seabeds in the area surrounding the ships and submarines.
It may also be used to measure the rise and fall of the tides in areas where the water is shallow.
The lead line is also one of the techniques for measuring the depth of water bodies, but it takes time and cannot be used in bad weather, so it has limited applications. The fathometer, on the other hand, can be used in bad weather and provides a more accurate result in a shorter period of time, making it more useful.
The same technique as the fathometer is used to send out sonic pulses in order to identify underwater things.
When it comes to submarines, a fathometer is quite important. Along with shoal water protection, other peacetime applications include identifying fish, assessing the thickness of ice in Arctic areas, and mapping the ocean’s surface.
A fathometer, also known as a Sonic depth finder, may be used to create a profile of the ocean bottom by recording thousands of soundings each hour over a long period of time. The use of echo sounders in oceanography and survey work to locate underwater pinnacles and shoals is common practice among hydrographers.
Conclusion
A fathometer is a device that uses echo sounding to measure the depth of the ocean or any other water bodies. Fathom is the unit for measuring the depth of any water body. A fathometer is more useful compared to conventional instruments to measure the depth because it can be used in bad weather and is more accurate with only an error of ± 7 cm. A fathometer is also used to locate the iceberg below the sea surface and schools of fish.
