Both statements are wrong... You can not inspect a foreign build boat to carry more than 12 pax but running OUPV charters is legal on foreign built boats... The 32v system on older Hatteras is fine... 32v parts are a non issue. What you get is solid fiberglass tanks instead of limited life alum or worst, heavy duty copper plumbing, etc
Every older 32 volt Hatteras I've run had a 12 volt battery bank for the generator and electronics from the factory.
And in the course of looking at dozens before buying my boat, not to mention my boat itself, and in the course of meeting several owners, I have never seen one that come from the factory that way. Newmar 32-12 converters were used and the gensets were 32 volt and started from the non-house bank. So obviously, there is no "rule" in that regard.
I think they started using 12 volt for the generator and common electronics bank around 1975. Newmar converters were used for the gauges and electronics.....the one I ran was a 1979 that had a 12 volt bank, so did a 1988 75' that was 24 volt engine. 12 volt gen. If not, it would be easy to do, 12 volt starter and alternator on the gen, 12 volt battery charger......and whallah.......
24, 12 volt Hi, I worked on a steel harbor tug years ago with 24 volt starting system for it's single 8V detroit and 12 volt for the electronics. The batteries were in series with one another. There was only one engine and one battery bank. In that case the 12 volts was picked off the 24 volt system. I think the 24 volt system was bonded to the hull on the NEG side but the 12 volts was ( + ) & ( - ) isolated in it's own cable. As I remember it worked fine. Was that a No No ?
No worries I ran an alloy Roamer the same way. the top battery was only used to make the 24vdc for starting, the bottom was a good 12vdc for everything on the boat. AS LONG, as nothing tried to use the top battery for a 12vdc source. For hits and giggles, My current ship has a 32vdc system. 8 volt batteries x 4 in series. My old 24vdc radar taps off of the third 8 volt battery on the port bank.
Um, no. There is no difference of the US build requirement between a SPV and a UPV under the Jones Act for a vessel engaged in coastwise trade (e.g. carriage of passengers). It may be easier to get an administrative waiver for an UPV, but I haven't heard that.