Well, on a high security application, I would use wlok padlocks. The
316 series stainless that they use should be highly resistant to saltwater.
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The cheapest lock's that do well in corrosive enviroments are probably the warded master locks...with a heavy greasing with a water resistant grease (aluminum bearing), they do pretty well. I would certainly reccomen that route over a cheap import pin tumbler lock in bad conditions. Not very secure, but ok in some applications.
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