Step 1 - REMOVE THE SALT!!!
Then remove as much of the coating as possible. Abrasive blast to near white metal if you can, then re-clean the surface.
Apply a coat 2+ mils thick [enough to fill the profile and cover the peaks by at least a 1/2 mil] high quality polyamide epoxy that is surface tolorant.
Let it dry /cure per direction, rinse of any surface contamination and allow the suface to dry then apply another 4 - 12 mils of polyamide epoxy.
Again do the dry and rinse thing between each consecutive coat.
For the life expectancy desired, consider flouropolymer urethane as a topcoat or at a minimum a high solids (60%+) acrylic aliphatic urethane.

Consider a 80 to 100% solids polyamide or polyamine epoxy. Over near-white abrasive blast.

I agree with above response, but note that no paint will last where walked on in a salty environment.  Better to use fiberglass grating or a high grade stainless.

This earlier thread may be useful:
PAINT COATING SYSTEMS ON US NAVY DESTROYERS
thread332-88537

The links still work; click "Approved Exterior Ship Coatings" and select "4 Non-Skid Walk."