Wreck search methods
Underwater obstructions (UWH) are investigated in wreck search with modern sonar systems. The systems include a side scan sonar (SSS) and a multibeam echo sounder. The SSS provides an image of the seabed and the objects lying on it. With the multibeam echo sounder, a 3D terrain model is created when the object is crossed during surveying and the lowest water depth at the UWH and the surrounding bottom is determined.
Historical: Wreck search in the past
Single beam echo sounder (SBES)
Using the single beam echo sounder, the depth is determined by emitting a sound signal.
An acoustic impulse is emitted vertically by the sonar. This impulse reaches the seafloor and is reflected from there. The sonar receives the reflected sound impulse and calculates the current water depth over the runtime.
Multibeam echo sounder (MBES)
A high-resolution three-dimensional model of the seabed and underwater obstructions is created by using a multibeam echo sounder. Instead of a single sound signal, several impulses are emitted simultaneously within a certain opening angle transverse to the direction of travel. The area covered by this signal depends on the opening angle of the sensor and the depth of the water.
Side scan sonar
A side scan sonar (SSS) makes it possible to image the seafloor and the objects on it similar to a photograph.
Sound impulses are emitted, which are backscattered differently depending on the condition of the seabed. From the reflection intensities it is possible to create a photo-like image of the seabed and of objects.
In addition to the location and extent of underwater obstacles, it is also possible to calculate the height above ground using the shadow cast.
To identify the underwater obstructions (UWH), an attempt is made to have each new object (UWH) examined by a diver. The use of divers results in a further independent deep measurement procedure with which the previously determined depth of the SBES/MBES can be controlled.
Diving on BSH ships
Underwater photograph of the diver
Remotely Operated Vehicle
As development of the Remotely Operated Vehicle (ROV) progresses, they are also increasingly being used in wreck detection. The ROVs are equipped with high-resolution cameras and also enable an optical inspection of the underwater obstacles.