ATLAS North America Proprietary
Sea Scan® ARC Explorer™ Manual
1 of 1
Page: 10
Issue: 4.2.1
2SFT1-0001
Manual
2.2.1.3
Prop Wash
Prop W ash shows in the waterfall when the churning waves and air bubbles produced by the ship's
propellers are picked up in the transducer's beam.
Figure 9: The effects of prop wash
This problem occurs mainly when a towed system is in shallow water. In deeper water, the
transducer's beam should be out of the propeller's wash, and the picture quality will improve. A
shallow-water solution to this problem is to tow the system ahead of the propeller from either the
front or sides of the ship.
2.2.1.4
Shadows
Shadows are produced when the sound waves transmitted from the sonar don't bounce off anything,
so there's no signal to return to the transducer.
Figure 10: A rock viewed from directly above
Depth sounders bounce their signals straight down, so the rock in this image is viewed only from the
top down.
However, just as the sun reveals shadows, sonar shadows are produced by the absence of sound.
