Planning
Map every device, its amp draw, distance from battery, and required wire gauge before running a single wire. Group circuits by function: nav lights, fish finders, bilge pump (always-on), accessories (switched). A hand-drawn schematic prevents expensive mistakes.
Wire Selection
Tinned marine-grade copper only. ABYC standards require tinned for all below-deck and exposed applications. Size gauge for circuit length and current using ABYC tables.
- Primary wire for most power runs
- Duplex for short runs where pos/neg travel together
- Battery cable for main connections
- All wire must be UL/SAE marine rated
Connections
Ratcheting crimp with adhesive-lined heat-shrink terminals creates gas-tight waterproof connections. Never wire nuts, tape, or push-in connectors on a boat — they fail from vibration and moisture within months.
Never Use
Wire nuts, electrical tape, or push-in connectors on a boat. These fail in marine environments within months.
Distribution
Fuse panel or breaker panel in a dry, accessible location. Single large-gauge feed from battery through main fuse to panel bus bar. Individual fused circuits to each device. Label everything.
Key Takeaway
Tinned wire, crimped heat-shrink connections, properly sized fuses, labeled distribution panel — the four non-negotiables for marine wiring.
Frequently Asked Questions
What wire for boats?
Tinned marine-grade copper with heat-shrink crimp terminals. Size per ABYC tables.