Furuno's public servicing sheet and installation guide keep returning to the same few weak points: a dry shaft, a worn guide, a spent zinc. This lesson summarizes what Furuno says to look at and how often.
At a glance
- Check cables, connectors and mains monthly
- Change the zinc yearly and whenever the boat is hauled
- Grease every 6 months in the manual, every 2 months in Furuno USA's service sheet
- Dry-dock yearly and clean the dome
About 8 minutes. Part of Own it in the CSH-8L MK2 course.
Monthly
Check the cables, the rear connectors, the grounds and the ship's mains voltage. Check the grease cotton for signs of water leaking in. Clean with a dry, soft cloth, with no chemicals and no spray paint or sealant near plastic parts.
Zinc
Change the zinc yearly or whenever the boat is lifted. Corrosion at the joint between transducer and shaft can cost you the transducer or flood the boat.
Grease
The Operator's Manual says to grease the grease points and the raised main shaft every six months. Furuno USA's 2025 servicing sheet is more frequent: grease the stainless shaft and the hoist worm and spur gear about every two months.
Yearly
Replace the grease cotton yearly. Inspect the U-gasket, which, not the grease cotton, keeps the water out. Check the tank guide and the main body flange, where idle boats can corrode the bronze insert onto the shaft. Furuno's yearly list also includes the trackball assembly.
The dome
Haul out yearly, clean the dome, and apply one coat of anti-foul. Furuno names two products, Seatender 20 and Chugoku Sea Grand Prix 660HS, and says not to mix or overcoat them. Furuno USA also lists alternatives that are water-based with no metals, solvents or alcohol. Never use solvents, sandpaper, a pressure washer or a steel scraper; use a wooden edge, soap and a Scotch-Brite pad.
The usual weak points
Furuno's servicing sheet and installation guide point to the same list: a corroded flange insert on idle boats, a worn tank guide, an over-tight grease-cotton retainer straining the hoist motor, a pinched transducer cable at the top of the shaft, line or kelp wrapped around the shaft, and a neglected zinc. Each is cheaper to find at haul-out than at sea.
Check yourself
Three questions
Sources
- CSH5LMK2 CSH8LMK2 Operator's Manual: Chapter 8
- CSH5LMK2 CSH8LMK2 Annual Servicing (Furuno USA tech tip): All items
- CSH8LMK2 Installation Guide: Notes
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.