How many sailboats have you ever seen with CrMo anything on it? None? There's a reason for that. Powdercoated or not, the marine environment will destroy CrMo in short order. Especially in salt water.
After a good powdercoating job the material choice would really be unsubstantial environmental wise. There would be no corrosion or rust to be heard of. Again we use crmo on dune buggies, hell even jeep's, that spend 90% of there life covered in wet mud. We had one at the shop for over a year that was caked in mud and grime. Cleans right off. The powdercoating is key. If it where not to be powdercoated than you would be absolutely right.