Green posts are a contact failure
Salt spray on lead terminals makes a crust that looks like a battery problem and measures like a cable problem. Voltage at the posts can look fine while the starter sees a weak connection. Cleaning, cutting back to bright metal, and using terminal hardware that actually clamps are the repair. 33 CFR 183.420 says each battery terminal connector must not depend on spring tension for its mechanical connection. Wing-nut hope and a spring clip are not that connector.
The box is wet and it still has to vent
The same federal section requires that metallic objects cannot contact ungrounded terminals, and that hydrogen can leave the boat. A gasketed Gulf console that keeps spray out also holds gas in if there is no vent path. We look at both: corrosion on the posts, and whether a flooded battery is charging in a sealed well.
Washdown is not a maintenance program
Hosing the cockpit after a day in Naples or Tampa Bay keeps the deck clean. It also drives water toward hatches. Dielectric grease on clean posts, covers that still fit, and a switch that is not sitting in the bilge do more than a weekly blast. We do not sell a magic spray as a substitute for a crimped lug.
AGM does not skip terminal care
Sealed batteries still have lead posts. Salt does not care that the cells cannot spill. Vibration on a Grady-White or Contender then works a loose lug. Heat in the console cooks whatever is left. Chemistry and corrosion are parallel jobs.
On a Gulf visit
We come to the lift or trailer. Bring a photo of the posts before you scrub them so we can see the damage. Lee County, Naples, and Tampa salt boats are this article. Inland lakes without salt air are a different corrosion story — usually just neglected clamps.
Switch studs and charger plugs
The posts are the obvious green. The battery switch studs and the charger plug on the transom are the next places salt lives. We clean those in the same visit on Gulf boats. A bright post into a green switch is a new bottleneck. Terminal grease goes on clean metal, not on top of crust.
Sources
If this is the job on your boat, see how we replace batteries at the boat. We come to you — Florida towns and counties.