White vinegar will effectively dissolve salt in the workings of marine hardware fittings. The part needs to be fully immersed in the vinegar for at least 24 hours (or longer depending on how much salt built-up there is) then flushed with fresh water and re-lubed as prescribed by the manufacturer. The mild acid of the vinegar can breathe new life into rope clutches, zippers, cam cleats, end fitting pistons and and a host of other common deck equipment. For tiller extensions and long twist-lock poles you can dam off a section of a rain gutter and fill it with vinegar (unless you have a very big bucket and a lot of vinegar!) so the pole is fully immersed.
This is where the old saying “If it doesn’t work, piss on it” came from. The uric acid from urine would free up frozen blocks, hinges and other deck equipment on the old sailing and merchant ships.
It is also good to pour vinegar into your head system about every month or so to help keep calcium deposits from building up inside of hoses and fittings. Fill the head bowl and then pump only long enough to draw the vinegar into the hose lines then stop and let it sit a while.