43 Post questions

120Vac/50A is an older electric service.
Most newer marinas do not offer this service any more.

Usually, a new 120-240Vac/50A male plug in installed on the shore service cord end.
This allows one of the two 120Vac lines to be used from the dock pedestal with the 50A service rating.

I have witnessed others using a new 120Vac/30A male plug also but that kind of defeats the utility and service of the 50A equipment already installed onboard. Probably pops the dock breaker often also.

Here is guide to help identify the plugs;
https://www.marinco.com/en/resources/quick-charts/qc-standard-cordsets

If you are not comfortable with electricity, please consult or hire a qualified electrician when making any modifications to your shore power needs.

Our Bertram originally came with a 120Vac/50A and a 240Vac/50A service. The thought was the 120V lead powered the important stuff; lights, battery chargers, outlets and the 240v lead powered the frills; A/Cs, range, water heater and laundry.
At first, I did modify the 120V/50A to a 240V/50A end but after adding more A/Cs to the boat, I converted that whole panel to 240V/50 Service.
At marinas, I have to make sure 2 X 240V/50A service or a 4 pin 100A service is available.
Never had a problem.

Lotts of great Post Kids on Yacht Forums. Give them time to chime in with the best answers on the rest of your questions.

Your pic is a 240Vac/50A connect.
The standard marina connect.
Check Marinco lead from post #3

That does look like a dual lead, 120Vac/50A panel.
Branch A & B are the two legs of 120Vac each.

In zooming in on the panel, It looks like no 240Vac appliances in use.

It maybe better described as all 120Vac appliances working on dual 120Vac legs.

I'm sure this gen-set is 240Vac also, Just like the sore power connect, supplying two, 120Vac lines.

Either way works fine.
I guess to help ensure the 2, 120Vac leads keep a balanced load on the gen-set, just a bad asp single 120Vac output would be easier.

You have to remember the theory of AC electricity. 240Vac is two 120Vac levels stacked on each other.
There is more into it with cycle phasing but usually invisible and does not require any additional thought (single phase theory).
You don't need to have 240Vac loads to run that way.

As I described our Bertram in post #3, that original 120Vac/50A service & panel, I had to split into 2, 120Vac legs to help keep the gen-set (also providing juice to the 240Vac options) load balanced.
Or else all the 120Vac stuff would be on just one leg of the two. That was the tip to just make it a second 240Vac panel and run the same shore power service and cords.
I'm still adding and changing that updated panel. Added a 240Vac ( 2 x 120Vac) inverter, updating the 2 ROs to 240Vac and yet another A/C unit.

Looking forward to the Post Kids to return from their boating weekend and help the OP answer the rest of his questions.

Post Kids are Cool,
71s Rule..

Hopefully the surveyor or previous owner answered some of your questions.
Remember to have the boat surveyed out very well including an engine tech going thru the engines and gen-set.

What engines are in her? 671s?