Thin Clients with Ethernet
You don't always need the additional computers to have full capabilities and cost as much

A "thin client" does not run a full copy of an operating system like Windows. It has only enough processing and memory to manage the display and human input for a session with an application. These are quite common, for example, at the different desks in a hotel: reservations, kitchen, bell captain, etc.

Thin clients, suitable for boat use, may physically look like only a flat-screen display, perhaps with a bit larger case than usual. You may not even need a keyboard or mouse; a number of thin clients have touch-sensitive screens that you've probably seen in restaurants for entering orders.

What if you have to run cable a long distance, or over electrical noise sources such as the engines?