The fish estimate mark lets you put a circle on a school and read its length, width and area. It is a way to compare one school with another, and this lesson shows how far to trust it.
At a glance
- Fish Estimate Mark 1 and 2
- Gives length, width, area and an estimate index
- New data appears after 5 transmissions
- Needs vessel speed, course and heading
About 6 minutes. Part of Run the CSH-10 in the CSH-10 course.
Placing the mark
The CSH-10 has two fish estimate marks, which you can register to function keys from the Mark menu. Put the cursor on a school and size the circle with the wheel knob until it covers the echo. The mark then reports the school's length, width and area, plus an estimate index.
What the index means
Furuno describes the index as a ratio for comparing two schools. It is not a weight, a tonnage or a species. If one school scores twice another on the same screen under the same settings, that is a useful hint about which is bigger, and nothing more.
Give it time and data
New estimate data appears after five transmissions, so a fresh mark reads blank for a few pings. Like target lock, the mark needs vessel speed, course and heading, so check the inputs lesson if it stays empty.
Compare like with like
Echo strength depends on tilt, gain, pulse length, power and how far away the school is. To compare two schools fairly, measure them at similar range and tilt with the same program selected, and repeat the measurement a couple of times. Use the estimate with the fish marks and the echo colors, not instead of them.
Check yourself
Three questions
Sources
- CSH10 Operator's Manual: Section 3, fish estimate marks
- CSH10 Operator's Guide: Marks
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.