Eye4Software Hydromagic

Hydrographic Survey Software

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Draft and sound velocity corrections

If you are not going to use either draft or sound velocity corrections, make sure both check boxes are unchecked and click "Next" to proceed to the next step.
Keep reading if you want to use one of these corrections.

Dynamic draft and sound velocity corrections

Sound velocity corrections

An echosounder calculates depth by sending a pulse and measuring the time it takes to get to the ocean floor and back.
With this time and the speed of sound through the water, the depth is calculated.

For fresh water, the speed of sound is 1500 meters per second, however, for salt water this speed depends on the salinity, temperature and depth.
Using the sound velocity correction option you can correct your sounding for salt water. Please do not use this function if this correction is already used in the echosounder.

Sound velocity corrections

Dynamic draft corrections

Dynamic draft corrections can be used to correct the downwards 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 what we call dynamic draft, and depends on the speed of the vessel. You can correct for this motions by creating dynamic draft correction table (speed versus draft).

Dynamic draft corrections