wrote in
:

But I want to be able to access WiFi Internet service, such as available
through the companies that are offering WiFi at marina's, and I want to
be able to access this from any pc on my wired boat-network.


The device you are looking for is a wireless router with point-to-
multipoint access, such as:
http://www.keenansystems.com/store/c...roducts_id=24&
osCsid=10e3853817a6eb3903e357bb5714a47e

The point to multipoint bridge acts as a wireless repeater to connect your
little notebook's pitiful low-powered PCMCIA wireless card to any area wifi
nodes within its range. This particular unit runs the full FCC limit of
200 milliwatts of power and can be configured to an external high gain
antenna, such as:
http://www.keenansystems.com/store/c...roducts_id=19&
osCsid=10e3853817a6eb3903e357bb5714a47e
an 8.5 dBi (about 6.5 dB stronger than a simple vertical dipole) that
remotely mounts to a 2" pipe atop your mast, if you're so inclined. At 50'
this should give you 5 miles of coverage area from your repeater to a wifi
node ashore....quite a bit further than the 300' you can get from the
notebook.

The unit has a single RJ-45 10/100 Ethernet LAN port which you would hook
to your system router's WAN port, similar to connecting a router to cable
or DSL modem at home. This will light up all your wired computers aboard
with access to the repeater via Ethernet, while simultaneously and
independently hooking up your wireless devices through the repeater to the
wifi, without being wired to the boat LAN.

As 2400 Mhz is NOT coax cable friendly at such a high frequency, it's best
to wire Ethernet up to the top of the mast where the antenna is and mount
this repeater in a weatherproof enclosure right under the antenna stick.
This nearly eliminates RF losses between the unit and its external antenna.
The Ethernet cabling to your router can be very long, indeed, with no loss
you can measure. There is also an Ethernet power injector that will
provide 48VDC to the mast-mounted repeater right through the Ethernet cable
the data comes through:
http://www.keenansystems.com/store/c...Path=3&product
s_id=16
As the use of this injector runs off 115VAC, you'll have to provide some
kind of inverter power if you want to run it away from the dock off your
house batteries. If you have 12VDC atop the mast you can switch on
independently from the nav lighting, using a 3A 12V IC regulator bolted to
the metal weatherproof box off your DC boat power will provide direct DC
power to the 11V port on the repeater without inverter or Ethernet
injector.....

As of 2 days ago, there seems to be an out-of-stock situation at this
vendor, but you can hunt around the net for the model number and buy it
from whomever you like.....

One of the regular posters here and I have been emailing each other in
plans to simply put the repeater and 8.5 dBi antenna atop his mast with no
Ethernet wiring to extend the range of his laptops on the boat, wirelessly.
It's a great idea because everyone I know who has a little notebook
wireless on their boat nearly has to be on top of a marina repeater to get
reliable service....