New Transducers 250C Manuale Utente

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If you are unfamiliar with basic sonar or need help determining what 

appears on the graph, this section may benefit you. This section 

is intended to teach the novice user how the Fishfinder 250/250C 

operates and how it can help improve fishing productivity.
To understand what the unit is displaying, it is important to have 

a general knowledge of how the unit works and how it determines 

what to display. Basically, the unit operates by transmitting 

sound waves toward the bottom of a lake, stream, or seabed in a 

cone-shaped pattern. When a transmitted soundwave strikes an 

underwater object such as the bottom, a piece of structure, or a fish, 

sound is reflected back to the transducer. The transducer collects the 

reflected sound waves and sends the data to the unit to be processed 

and displayed on the graph. The underwater data is displayed on the 

graph in the order it is returned (first returned = first on the graph). 
Generally speaking, if the only thing between the transducer and the 

bottom is water, the first strong return will come from the bottom 

directly below the transducer. The first strong return sets the bottom 

level. Weaker secondary returns provide the detailed data. 
The Fishfinder 250 displays sonar returns as shades of gray; stronger 

returns are darker, and weaker returns are lighter. On the Fishfinder 

250C, sonar returns appear as red (strongest), orange (strong), 

yellow (medium), green (weaker), and blue (weakest).

The diagram below shows an underwater scene as it would appear 

on the graph.

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The fish in the diagram is currently in a dead zone and is not 

detected by the sonar. The fish is in the coverage area of the 

transducer, but the first strong return set the bottom level above the 

fish. The first strong return to reset the bottom level below the fish 

will enable the fish to be detected.
The following pages will show how this data can help you improve 

your fishing.