Water Column page
To achieve correct echo information, the current environmental parameters must be known to the EK80 system. The Water Column page collects these parameters. These must be defined to match the current conditions.
How to open
This page is opened from the Environment dialog box. The Environment dialog box is opened from the Setup menu.
Description
In order to obtain accurate depth readings and fish echoes, it is very important that the sound speed through the water is
set correctly. Several parameters are required to calculate the correct sound speed value. If these parameters are not known to you, use the default value 1494 m/s. This is a typical mean value for sound speed in salt water. In fresh water we suggest that you set the sound speed value to 1450 m/s.
Details
Conditions
Use this setting to set up the EK80 system for operation in fresh or salt water.
Sound travels with different speeds in salt and fresh water. For this reason, it is important that the EK80 system knows your water profile. The default setting is Salt.
Fresh water/salt water settings, temperature, salinity, acidity and depth as well as operating frequency for each transducer
are all used for calculating absorption. The absorption value is in turn used for each sample.
Parameters
Use these settings to provide manual values.
Fresh water/salt water settings, temperature, salinity, acidity and depth as well as operating frequency for each transducer
are all used for calculating absorption. The absorption value is in turn used for each sample.
Temperature
Provide the current water temperature. Once the salinity and temperature information is provided, the EK80 system calculates the sound speed and absorption.
Salinity
Provide the current salinity. Once the salinity and temperature information is provided, the EK80 system calculates the sound speed and absorption.
Acidity
The equations used by the EK80 system to calculate the absorption requires a value for acidity. Unless you have any specific reasons to apply a specific value, use the default value of 8 pH.
Depth
The equations used by the EK80 system to calculate the absorption and the sound speed requires a value for depth. This is the current depth under the keel.
Latitude
The equations used by the EK80 system to calculate the sound speed requires a value for latitude. This is the vessel’s geographical latitude. For increased accuracy, you are permitted to provide a manual latitude. Unless you have any specific reasons to apply a specific value, use the default value of 45 degrees.
Sound Speed
In order to obtain accurate depth readings and fish echoes, it is very important that the sound speed through the water is
set correctly. The value of Sound Speed is used to convert between time and range, for all samples. The operator determines the method of obtaining the Sound Speed value.
Calculated
Select Calculated to allow the EK80 system to calculate the sound speed and the absorption based on the parameters you have supplied.
Manual
This option allows you to input the sound speed manually. This can be relevant if neither a sound speed sensor nor a CTD (Conductivity Temperature Depth) sensor is available.
Profile
Select Profile to collect the sound speed data from the source file provided by a CTD (Conductivity Temperature Depth) sensor. Go to the Profile page to select the profile to be used.
Absorption
The absorption curve is calculated and drawn using the parameters provided.