To answer pschoonfeld's question, the Ubiqiti PicoStation2 can act as a wireless repeater in WDS (wireless distribution system) mode. However, this only works with another compatible WDS device configured specifically to talk WDS with your device. In short, it won't work with the shore Access Point you are connecting to.
Instead, you generally have to have your boat's high-powered WiFi station connect to a shore access point, and bridge or route the traffic to the hard-wire Ethernet port. Then, if you want to distribute wirelessly onboard, you need a second WiFi unit, for which many use a Linksys WiFi router.
The alternative to this is to use a WiFi unit with dual radios (in think Engenius makes one) or something like the Engenius EOC-2610, which has a feature called Universal Wireless Repeater that uses a single radio for both the shore connetion and it's own access point.
I have an Engenius EOC-2610 configured this way. The only thing I don't like with it so far is that it needs 48Vdc.
Instead, I am trying out a Ubiquiti PicoStation2, even though it doesn't have a Universal Wireless Repeater feature, as I think it will run on the boat's 12Vdc system. Does anybody know where I can buy a Power-Over-Ethernet injector that will wire directly into the boat's 12Vdc system?