Darn Trailer Brakes is locking up !

[RidgeRunner]

That sucks, can you feel the brakes dragging? Looks like the brakes ain't working 100% in the second picture. Normal wear on the first. Rust on the rotors is a pain, it happens on mine with the boat just sitting in the yard. The fact that there is still rust visible on the friction surface on the inboard side of the rotor is a good indication something is wrong. The rust gets machined off by the pads and should disappear after several miles of stop and go driving. My brake calipers are off some GM car or truck, they slide in and out on bushings to keep in proper alignment with the rotor. IMO, that is the critical point to maintain on the type I have. The bushings ride on the slides which are the two bolts that bolt the calipers to the caliper bracket. I like the disk brakes much better than the drum style that I have owned because they are simple. The only other moving part to the disk brake setup is the piston in the actuator and the brake piston in the caliper, neither one should be affected much by salt water, only the outside of the brake piston would get wet when dunked, there is a rubber boot there to prevent water intrusion to the back side of the piston.(where it rides in the caliper bore)