Building brushless motors that work when submerged in salt water is almost trivial. The only parts that matter with respect to corrosion is the insulation on th

Building brushless motors that work when submerged in salt water is almost trivial. The only parts that matter with respect to corrosion is the insulation on the windings and the material the bearings are made from. The rest you can just paint with whatever you'd normally use to avoid corrosion.