The Saltwater Kit with zinc plate and 10′ wire is made for use in saltwater applications to slow corrosion and lengthen the life of your boat lift. It is as simple as bolting the wire onto the inside flange of the I-beam that is closest to the dock and tossing the zinc plate into the water.
Saltwater is a very corrosive environment because the salt that is present is a good conductor of electricity. It creates a lot of free ions which speed up the oxidation of iron (a main component of the steel a boat lift is made of). This oxidation is what we know as rust. Any part of the lift that is underwater is subject to corrosion.
Different metals give up electrons to become ions easier than others. Metals with more negative electrode potential are more likely to give up electrons and become corroded. Some elements like zinc have fewer negative electrodes than steel, meaning it is more ready to give up electrons and become corroded compared to steel.
If you introduce an element like zinc to the steel, it becomes what we call a sacrificial anode and saves the steel by getting corroded first. The sacrificial zinc plate of the saltwater kit will slow corrosion and extend the life of your boat lift.