Range is the first thing you change and the easiest to misuse. Pick the scale for the job and know what it costs you.
At a glance
- 21 range scales from 50 m to 2,000 m
- Sound travels about 1,500 m per second in seawater
- During target lock the range changes automatically
About 6 minutes. Part of Run the CSH-10.
The scales
The default range scales, in meters, are 50, 60, 70, 85, 100, 125, 150, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 1000, 1200, 1600 and 2000. Use the RANGE key to step up or down.
How long does an echo take?
Sound travels through seawater at roughly 1,500 meters per second, a little faster in warm, salty water and slower in cold or fresh water.
Why bigger range means a slower picture
The sonar has to wait for an echo to come back before the next ping. Sound moves about 1,500 meters per second, so an echo from 400 m takes roughly half a second to return and one from 2,000 m takes more than two and a half. The manual's manual TX interval setting reflects this: it fixes the ping rate according to the sonar range.
Choosing a range
A practical habit, not a Furuno rule: search wide to find the activity, then step the range down as you close on a school so it fills more of the screen and you get a faster picture. If you are in shallow water, a very long range mostly paints the bottom.
A special case
While target lock is active the range changes automatically and, by default, you cannot change it by hand. The target lock lesson covers this.
Watch it done
Furuno USA publishes these CSH-10 videos. They play from YouTube when you press play.
Operator Orientation Part 1: initial settings, P settings and manually moving the hoist unit
Check yourself
Three questions
Sources
- CSH10 Operator's Manual: Section 1.3.6
- CSH10 Explanation of User Settings: TX interval
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.