系统与操作指南
Bonding and grounding on fiberglass yachts
DC negative, bonding bus, and galvanic protection on GRP cruisers — what owners should verify.
Overview
On fiberglass yachts, the DC negative (battery return) connects to engine block and often a bonding bus linking underwater metals. Bonding is not the same as shore earth — confusion causes stray-current corrosion.
What gets bonded
| Item | Typical bond |
|---|---|
| Engine block | DC negative return |
| Through-hulls (bronze) | Bonding bus + sacrificial zinc |
| Shaft / prop | Via shaft brush or collar zinc |
| SSB radio ground | Separate RF ground plane — not always bonding bus |
Owner checks
- Zinc consumption — rapid loss suggests galvanic or stray current
- Continuity — meter check from zinc to bonded fittings after haul-out
- Isolation transformer — on shore power reduces marina galvanic issues
See through-hulls and shore power basics.