Boat wiring starts with the right wire. This collection covers marine-grade electrical cable for 12V and 24V installations: tinned single-core and twin-core cable in the common cross-sections, heavier battery and starter cable, and the multi-core cables used for lighting circuits and instrument runs.
The word that matters is tinned - each copper strand is coated so salt air can't creep along the cable and corrode it from within, which is exactly how untinned automotive cable fails afloat. Size cable to the load and the length of the run (voltage drop matters at 12V: go a size up on long runs), use proper crimped and heat-shrunk terminals rather than twisted joints, and fuse every positive feed close to the battery. Wired that way, a boat's electrics stay reliable for decades.
Frequently asked questions
Why do boats need tinned cable?
Tinned copper strands resist the corrosion that salt air drives along ordinary cable, preventing the green, high-resistance decay that causes flickering lights and mystery failures in untinned automotive wire.
What size cable do I need for 12V boat wiring?
Size by both current and cable length - voltage drop is significant at 12V, so long runs need a larger cross-section than the current alone suggests. Aim for under 3% drop on critical circuits, going up a size when in doubt.
Can I use household or automotive cable on a boat?
It will work briefly, but untinned copper corrodes quickly in the marine environment and solid-core household cable fractures with vibration - marine tinned multi-strand cable is the reliable choice.
