Draft and sound velocity corrections

More information on sound velocity and dynamic draft corrections can be read below. If you are not going to use either draft or sound velocity corrections, make sure both checkboxes are unchecked and click the "Next" button to proceed to the data correction page.

When applicable, set up sound velocity and dynamic draft corrections on this page.

Sound velocity corrections

An echo sounder calculates depth by sending a pulse and measuring the time it takes to reach the ocean floor and return. With this time and the speed of sound through the water, the depth is calculated.

For freshwater, the speed of sound is 1500 meters per second; however, for saltwater, this speed depends on salinity, temperature, and depth (pressure). Using the sound velocity correction option, you can correct your sounding for saltwater. Please do not use this function if this correction is already used in the echo sounder. To generate a sound velocity correction file, click the 'Editor...' button to start the sound velocity file editor.

Use the sound velocity editor to generate or alter sound velocity profile files when applicable.

Dynamic draft corrections

Dynamic draft corrections can be used to correct the downward motion of the ship.

For instance, when using a speedboat, you may notice that when the speed increases, the rear of the ship lowers while the front raises. This is known as dynamic draft and depends on the speed of the vessel. You can correct for this motion by creating a dynamic draft correction table (speed versus draft). To generate a dynamic draft correction file, click the 'Editor...' button to start the dynamic draft correction file editor.

Use the dynamic draft editor to generate or alter dynamic draft profile files when applicable.