Cut back a suspect wire on an older boat and you often find green copper well beyond the visible damage. Salt laden air wicks along the strands inside the insulation, so the corrosion you can see is rarely the full extent of it.
Corroded conductors add resistance. Resistance means voltage drop, heat and unreliable operation, and in the wrong place, a fire risk. It is worth taking seriously even when everything still works.
A house is dry, still and stable. A boat is damp, salty, constantly moving and full of dissimilar metals. Untinned copper, the standard in domestic wiring, has no protection against that, so it corrodes from the cut end inwards.
Tinned marine cable, fine stranded for flexibility, with adhesive lined heatshrink over correctly sized crimps, resists exactly the conditions that destroy domestic cable. It is more expensive per metre and dramatically cheaper over the life of the boat.
Terminations matter as much as cable. A perfect cable with a bad crimp is still a bad circuit.
When we find green wiring, we cut back to bright copper, which is often further than expected. Patching at the visible point leaves corroded conductor buried in the run, and the fault comes back the following season.
Where a whole loom shows the same condition, replacing sections is usually better value than repeatedly repairing it.
Ventilation, keeping joints high and dry, supporting cable properly, and using the right materials in the first place are what stop it happening again. So does fixing the deck leak above the locker, which is frequently the real cause.
It can be dangerous. Corroded conductors run hotter and drop voltage, and in a high current circuit that is a genuine fire risk, so it is worth assessing properly.
Surface cleaning a terminal helps briefly, but corrosion inside the strands cannot be cleaned out. The reliable repair is to cut back to good copper and remake the connection properly.
No. Often it is confined to particular runs or areas near a leak. An inspection tells you whether it is localised or systemic before you commit to anything.
We assess how far the corrosion runs, repair or replace in tinned marine cable and deal with the damp that caused it.