Yes, but there aren't many 48V DC appliances -- radios, lights, gauges, etc. Many larger boats have 24V DC systems, and there are quite a few boat electronics

Yes, but there aren't many 48V DC appliances -- radios, lights, gauges, etc. Many larger boats have 24V DC systems, and there are quite a few boat electronics that run on either 12V or 24V (though you will still need either a 24->12v converter for many things, or be able to tap 12v from the battery bank).