You want the easy way or the post grad geek way?
The simple way: The EOC-3220 has a feature called "Universal Wireless Repeater". You link it to a shore side access point and it gives wifi Internet access to all the computers on the boat. The 3220 also has a simple polling feature that lets you see what access is available and choose which one you want to connect to. Very simple to set up but the downside is that all the router tasks are handled by the shore side router so once out of range there is no network on the boat.
NOTE: The EOC-3610 and the new EOC-2610 is more powerful but it does not have the Universal Wireless Repeater feature.
The Geeky way: The EOC-3220, 3610 or the 2610 can be set up as a bridge. In this configuration you have a router on the boat, wired or wireless, that manages the local network and the 3220 serves the same purpose as your cable or DSL modem at home, to connect an on boat network to any shore side access point for Internet access. This gives you a private, always on local network on the boat that has Internet access when you are in range of an access point.
The downside is that it can take a 3rd degree black belt geek to set it up. Fairly good description of the basic process on the link given previously. The trick, however, which is not covered is to set up the local router so the 3220 doesn't see the router or any of the wifi devices on the boat and connect to itself. It's called the Whopp bird effect. * I have set up a couple. The cost is about $250 for the 3220 and a router and a couple thou for hair transplants and Rogaine.
*Whopp bird, aka Swan Swivel, Zuni bird: A bird that flies in ever decreasing circles until WHOPP! It flies up it's own ass and disappears.
