Effects Of The Vessel's Speed - Simrad CE33 ChartSounder Manual

Chapter 7-14

7.12 Effects of the vessel's speed

The presentation of fish on the CE33 depends directly on the vessel's
speed, as well as on the depth of the fish. When the vessel is at rest,
the echo traces will appear stretched and flattened. As the vessel's
speed becomes greater, the echo traces will become shorter and
more arched. The reason for this change in appearance is that as the
vessel speed increases, fewer number of sound 'pings' strike each
fish. A low vessel speed will provide the most accurate information
of where fish are loacted.
CE33 Echosounder operation