Gain is how loudly the sonar listens. Too little and you miss fish; too much and the screen fills with noise. The CSH-10 lets you set it separately for near and far water.
At a glance
- Gain: 0.0 to 10.0, usually 3 to 7
- Near gain and far gain: 0 to 10, below 5 reduces and above 5 increases
- Near and far distances are set in the System menu
About 7 minutes. Part of Run the CSH-10.
Overall gain
The GAIN key sets the overall gain from 0.0 to 10.0. Furuno says a setting between 3 and 7 is usually suitable. Start in the middle, then raise it until faint echoes appear and back it off when the screen starts to fill with speckle.
Why near and far are separate
Water close to the boat usually returns strong echoes and noise, while distant water returns weak ones. Near gain controls the area inside the near gain distance and far gain controls the area beyond the far gain distance, both from 0 to 10. A value below 5 reduces gain and above 5 increases it. The two distances themselves are set in the System menu.
A note on defaults
Furuno's manual describes the default near and far gain area as within 300 m, while its AGC description uses 270 m. Where documents differ, the numbers on your own unit and your installer's settings win.
Watch it done
Furuno USA publishes these CSH-10 videos. They play from YouTube when you press play.
Operator Orientation Part 6: near gain, far gain, AGC near and AGC far
Check yourself
Three questions
Sources
- CSH10 Operator's Manual: Sections 1.3.7 and 2.1
- CSH10 Explanation of User Settings: Near gain and far gain
This lesson summarizes Furuno's public documents in our own words. Limits and settings differ by model and software version, so your own manual and your installer have the last word. OmniCSH is an independent project, not a Furuno program.