Originally Posted by tucker99
Cables on boats in salt water often corrode under the plastic sheath. That happens where the sheath gets a cut or the like and salt mist does it's damage.
If the cables are just gummed up, a solvent and lubricant may help but getting a 20 foot cable lubed is a lot different than a three foot motorcycle cable.
FYI, WD-40 is not a lubricant. It is a penetrating solvent and dissolves a lot of things. Ofter it seems to work because it dissolves old gummed up grease and turns it into softer old grease
It does help to coat the exposed ends of control cables to reduce moisture penetration and corrosion but once the metal sheath or inner core start to corrode, it's time for new cables.