Interconnecting Ethernet Switches
If you need it, even more complex arrangements are possible

You can interconnect Ethernet switches, and, if you use optical fiber rather than wire, the distances between switches jump to distances more like those on an aircraft carrier rather than a fishing vessel. It's unlikely, but you just might have a difficult enough path, between points on a large vessel, to need this.

A more likely reason to want such interconnection is that the cable path would go across a source of electrical noise, such as the engines or generators, optical fiber is essentially immune to "static".

Are there different groups of users on your boat, or other facilities such as fish processing plants?