I also have a Vizio Smart TV. I think that the problem is how your marina does authentication. There are several ways to do it:

No authentication- Open, just click on the router name and away you go.

Local password protection- The router asks for a password. You supply the one given to you by the marina and then connect. The Vizio handles this one nicely. It is how I connect my Vizio to my local password protected wifi router.

Remote (for lack of a better term) authentication- The router is not password protected, so it looks open to you. Burger King, Duncan Donuts, etc use this method. But you can't do anything until you open your browser, click on some URL and then an authentication menu pops up- sent by the IP provider not the local wifi router. Some only ask that you accept their terms- Burger King. Others ask for a password and your acceptance of those terms. Hotels seem to have most of these schemes, and I suppose the people who sell IP systems to hotels also target marinas. I don't think Vizio can handle this type of authentication as it does not have a generic browser, but I could be wrong.

David