Anyone here, at any price, succeeded in doing what I thought to be a
manifestly simple, analogous to HAM repeaters, job of being able to surf
wifi-ish (no wire from my laptop to whatever gear) from my deck or dink or
wherever I am within range of my mast top, seeing the available (with
amplification and better antenna) shore points as amplified by the setup,
and choosing from those available without having to manually (over url)
configure the hardware each time?

I'm going to setup just this type of rig sometime this summer. I'm going to
use an old PC laptop running linux to do it. The goal being to pick up a
shore-based WiFi network and "repeat it" to on-board PCs. The only
"complicated" part is how to tell this router PC to connect to the on-shore
access points. If you're willing to do the 'command line dance' it's just a
matter of knowing which wlanconfig setups to use. But I seem to recall
seeing a couple of web page setups that could be used to do it as well. As
in, surf from the on-board PCs to a server page on this router and use that
to tell it which of the detected access points to use and start routing.
I'll certainly summarize whatever progress I make with it but it'll be at
least another two weeks before I can get back into it.

Meanwhile, if you've got an old laptop that's got at least 64mb of RAM and a
Pentium 233mHz then take a look at getting it setup with "Damn Small Linux"
http://www.damnsmalllinux.org

-Bill Kearney