Found an article in the "Atlantic" from 2014 which discusses how the Navy was/is using ships as floating prisons. And one from USA Today. Apparently John Kelly is a proponent of keeping the bad guys off the soil until they can get to court. While these article discuss non-US citizens, as long as the accused are comfy, the idea still holds water….arg arg arg.
https://www.usatoday.com/story/news/world/2017/11/28/u-s-coast-guard-operating-secret-floating-prisons-pacific-ocean/900462001/
https://www.theatlantic.com/international/archive/2014/06/americas-floating-prisons/373577/
The Atlantic archived = http://archive.fo/FfpFN