Glossary Term
Bonding System
The bonding system is the network of conductors that electrically interconnects selected non-current-carrying metal parts of a yacht. In boat and yacht standards, bonding conductors connect metal parts to the vessel’s bonding system so that those parts remain at the same electrical potential. Within yacht practice, that usually includes underwater metals such as through-hull fittings, seacocks, rudder gear components, struts, and other protected metallic items.
Its purpose is tied to corrosion control and electrical safety, but it is not intended to act as the normal current return path for the DC system. ABYC guidance states that bonding and DC grounding conductors are not to be used as battery negative return conductors. That distinction is central on superyachts with mixed metals, shaft equipment, stabilizers, and complex underwater fittings, where poorly planned bonding can either weaken cathodic protection or create stray-current trouble instead of preventing it. Most rectification work sits in the electrical and electronic scope even though the symptoms often appear first on metal hardware outside the switchboard.
Bonding-system decisions are rarely visible to guests, but they show up clearly over time in corrosion patterns, anode consumption, and the condition of underwater fittings. When a yacht goes through refit, shaft work, underwater metal replacement, or electrical-system changes, the bonding layout deserves the same level of review as the visible mechanical work around it.