Not many things escape the wrath of saltwater, and casters are no exception. A caster and salt water are a challenging mix because a caster has a lot of moving parts. And the last thing you want to enter the picture is corrosion. The caster’s swivel section, wheel bearings, and all the exposed metal parts are areas where you need to choose carefully.
When choosing your wheel, consider both the core material and the polyurethane you choose. Cast iron cores rust very quickly when used in or near saltwater. For this reason, aluminum is your best bet for the wheel core. In addition, you can also use a metal core that is encapsulated by polyurethane.
When choosing what polyurethane to use, MDI and TDI are the two main diisocyanates used in the production of polyurethane. Of the two, TDIs do better in saltwater applications. TDI will hold its form at higher temperatures and has a better bounce back rate from compression as well.
316 stainless steel is the ideal metal to use when in saltwater applications, offering improved corrosion resistance. The downside is that it is very expensive. Nickel plating will hold up the best next to stainless steel.
Powder coating the rig is another viable option. The only downside is when the powder coating chips, allowing saltwater to infiltrate behind the powder coating and break down the steel. Zinc plated casters are a much cheaper option. However, these types of casters won’t last long in saltwater environments.