The transducer is the most expensive part of the system and the part most likely to be hurt by a mistake. This lesson covers the rules Furuno publishes for lowering, raising and retracting it.
At a glance
- 20 knots maximum with the transducer down
- Under 18 knots to raise or lower it
- Check the water depth before you lower
- Auto retraction is on by default
About 7 minutes. Part of Run the CSH-10.
Before you lower it
Check the water depth first. If the water is too shallow the transducer can touch the seabed and be damaged. Furuno also warns against transmitting with the transducer out of the water. Slow the boat to less than 18 knots before you lower or raise it; the manual repeats this in both the lowering and raising procedures.
What the lights and the screen tell you
On the hoist, an LED flashes while the transducer is moving and stays lit once it is fully down or fully up. On the display, the transducer position indicator is green when retracted, red while it is moving and yellowish brown when it is protruded. If the boat is too fast during a lower or raise, a SHIP SPD ALARM message appears.
The two speed limits
- 20 knots is the limit with the transducer lowered.
- 18 knots is the limit while it is being lowered or raised.
Those are the CSH-10 figures in the Operator's Manual. Other models differ, so check your own manual.
Auto retraction
Auto retraction is on by default. When the boat's speed goes over the speed an operator has set, the sonar raises the transducer by itself. Two cautions from Furuno: it works from the speed data the sonar receives, so if that external data is wrong it may act at a different real speed, and you should always get below 18 knots yourself regardless of the setting.
What speed should it be set to? Furuno's annual service sheet lists the auto retraction speed as 15 knots. Some installers and captains quote a lower figure; this site's older pages used about 12 knots. Treat 15 knots as the published checklist value and have your installer confirm the setting on your boat.
Powering off
Retract the transducer before you turn the power off. The Operator's Guide adds that if power is cut while it is protruded, the unit is raised and retracted automatically.
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: Safety notes (p. iii), sections 1.3.2 and 1.3.8
- CSH10 Operator's Guide: Hoist operation
- CSH10 Recommended Annual Service: Performance checks
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.