Boat Rewiring

When a boat's wiring has been added to over years, patched after faults or simply aged in salt air, a rewire is often more sensible than chasing one fault after another. We carry out full and partial boat rewiring at the berth or in the yard, from Brighton to Southampton, with a written quote agreed first.

A rewire is not about new cable for its own sake. The aim is a system where every circuit is protected, sized for its load, routed where it can be inspected and labelled so you or the next electrician can follow it. That is what makes faults rarer and easier to find.

This page covers rewiring as a job in its own right. If the electrics are one part of a wider refit with lithium, inverters and new electronics, our yacht refit electrics page is the better starting point.

Signs a boat needs rewiring rather than repair

One fault is a repair. A pattern usually points to the wiring itself:

Full rewire or partial rewire

A partial rewire replaces the worst areas, often the main battery cables, the distribution panel and the circuits that live in the bilge or forepeak, while keeping wiring that tests sound. A full rewire replaces everything from the batteries outward. Which suits depends on what testing shows and how long you plan to keep the boat. We will tell you plainly what is worth keeping.

How a boat rewiring job is planned

We start by tracing and testing what is there and agreeing what the boat must run. From that comes a circuit list, cable sizes based on load and run length, and a protection plan. Marine-grade tinned cable is used throughout, with crimped and sealed terminations, supported runs and a new or rebuilt distribution panel where needed. When the work is finished it is tested and labelled, and you get a documented record of the circuits.

Boat wiring basics owners often ask about

Most boat circuits are 12 or 24 volt DC from the batteries. Boats with shore power or an inverter also have 230 volt AC, which is a separate system with its own protection and earthing and must never be mixed into DC wiring. Cable gauge is chosen for the current and the length of the run, because voltage drop over a long run to the bow can leave equipment underpowered even when the fuse never blows.

Fitting a rewire around the boat's season

Rewires are easiest when the boat is laid up and lockers can be emptied, but partial work can often be done afloat between trips. Tell us when the boat is free and we will plan the sequence so the essential circuits are back in use as early as possible.

Yacht refit electrics · Boat electrical repairs · Marine electrical installation

Frequently asked questions

What is a boat wiring harness?

It is a bundle of cables made up for a particular job, such as the engine instruments or a lighting run. On older boats a failed harness is often better replaced than repaired joint by joint.

What gauge is boat wiring?

There is no single gauge. Each cable is sized for the current it carries and the length of the run, so a long feed to the bow may need heavier cable than a short one of the same load.

Is boat wiring AC or DC?

Most of it is low-voltage DC from the batteries. Boats with shore power, a generator or an inverter also have a separate 230 volt AC system with its own protection.

How do you troubleshoot boat wiring?

Methodically, from the supply to the load: checking voltage under load, then each connection and protective device in turn. Guessing and swapping parts tends to cost more than proper testing.

What does it cost to rewire a boat?

It depends on the size of the boat, how much is replaced and access. After an assessment we give a written, itemised quote.

Talk to us about a rewire

Send the boat details and a few photos of the panel and battery area, and we will arrange an assessment and written quote.