Echo sounder

Question 1

Describe how an echo sounder measure the range of he sea bed. With the aid of a diagram

Answer 1

An echo sounder measures the range of the seabed by sending out sound waves, typically in the form of a pulse. These waves travel through the water and bounce off the seabed. The device then detects the time it takes for the sound wave to return (echo) to the sensor. Using the speed of sound in water and the time taken for the echo to return, the echo sounder calculates the distance to the seabed. This data is then used to create depth profiles or maps of the ocean floor.

Question 2

2 standard frequencies for echo sounder and who each might be better and where

Answer 2

Two standard frequencies for echo sounders are typically 50 kHz and 200 kHz.50 kHz: This lower frequency is better suited for deeper water and can penetrate through thicker layers of sediment. It’s ideal for deep-sea exploration or mapping where the depth is significant.200 kHz: This higher frequency provides higher resolution and is better suited for shallower waters or areas where fine detail is needed, such as near shorelines, reefs, or shallow water navigation.The choice between these frequencies depends on the specific application and the depth of the water being surveyed.

Question 3

Two advantages and 2 disadvantages of electromagnetic log over doppler log.

Advantages of Doppler log

Answer 3

Advantages of an Electromagnetic Log over a Doppler Log:

1.	Accuracy in Shallow Water:
2.	No Dependence on Water Conditions: Electromagnetic Logs do not rely on the physical properties of water, such as density or salinity, to measure speed.

Disadvantages of an Electromagnetic Log compared to a Doppler Log:

1.	Installation Complexity:
2.	Limited Accuracy at High Speeds

Doppler
Can read SOG
Can also read athwartship speed
Accurate is shallow water

Question 4

State TWO potential sources of error of a Doppler Log when Calculating speed.

Answer 4

1. Environmental conditions ex water salinity and density
2. Instrument calibration

Question 5

Advantages and disadvantages of electromagnetic log.

Answer 5

Advantages

Simple
Low maintenance
Accurate at low speeds
Insensitive to fouling
No moving parts

Disadvantages

1. Cost
2. Installation
3. Limited to speed through water
   Not easy to access for maintenance
   Required calibration for different water salinities and temperatures