Kurt Struyts explains: “A depth survey is like a land survey, but under water. We map out the depth of the bottom with sonar equipment aboard the Echo. We do this to ensure the safety of navigation. Of course, if we allow ships of a certain depth, we must also ensure that the bottom is deep enough.

With depth soundings, we also monitor dredging operations. In addition, we occasionally assist in retrieving sunken objects, such as lost cargo, fenders or a bicycle. Thanks to the sonar equipment, we can track a grabbing crane live in 3D.”

Surfing along on the waves

In 1986, the Port Authority was still using single-beam sonar to measure the distance to the bottom. Today, we use multi-beam sonar equipment to more accurately map the surface of the bottom. The principle of a sonar is that you send sound waves to the bottom. For every ‘ping’, every audio signal we send, we receive 1,024 signals. With single-beam, this is just one signal. On average, with both multi-beam and single-beam, we do 30 to 50 pings per second.

A depth map from 1986, made with a single-beam sonar.

Dredge trace detection

There are some places where the bottom changes little. For the Zandvliet-Berendrecht lock complex, on the other hand, it does.

Today we use multi-beam sonar equipment to create a more accurate depth map.

On the colour chart, therefore, you can see a lot of dredge trace marks. Traffic and lock movements cause the slush to move faster towards the docks. So we monitor that very closely.
Source: Port of Antwerp Bruges