WRT54G as long range receiver on boat

Discussion in 'Cisco/Linksys Wireless Routers' started by scuttlebutt, May 20, 2008.

  1. scuttlebutt

    scuttlebutt Guest

    Hi there,

    I live on a sailing boat, and frequently come across networks I just can't quite reach with standard equipment. I was wondering, with a Linksys router and firmware upgrade, could I raise a good quality aerial up my mast, and use the router as a long range WIFI transciever? I can't recall what the technical term is, but a rudimentary description would be that the router connects to an available distant network, and then shares the wireless signal locally within the boat -

    Is that possible? I saw a megayacht today with a Lobo 912R unit on the mast (the mast was on the ground for repair) and it got me thinking about a poormans WIFI setup...

    Thanks, sb
  2. HennieM

    HennieM Network Guru Member

    You sure can. The secret is the antenna and minimizing signal loss. The general rule is to get as strong an antenna as you can, as a strong antenna increases both transmit and received signals. I'll mention some introductory info here, but you'll have to google and read up quite a bit to get to terms with all the details in play.

    Two basic antenna scenarios I can think of:

    1.1) If you use the wireless only when docked - i.e. the boat is fairly stationary both i.t.o. movement and orientation - you can go with a directional antenna which focuses your transmitted signal and the signal received from the distant network. The antenna most suitable for this setup would be like a grid or dish. As such antennas typically have beam widths of less than 10 degrees, you would have to devise a mechanism to swing around and elevate this antenna so you can focus it on the remote access point.

    1.2) If you can't live with such a small margin, you might consider a panel-, patch-, or even a Yagi antenna. These typically have beam widths in the 30 to 40 degrees, but you would still require rotation capabilities.

    2) Alternatively you can go with a strong omni-directional antenna. This antenna spews your signal in a horizontal donut around the antenna, so it would not require rotation nor elevation. However, omnis of reasonable size, have much lower strength than directional antennae. They are also not very neighbor friendly as you are blasting your signal all over... ;)

    The choice of antenna and how strong a signal you can transmit is further dictated by where you are at any point in time. In ETSI waters (I would think the same applies on water as on land), your total transmitted signal may never be stronger than 20dBi. In FCC waters, the narrower your beam width, the stronger the signal you can transmit. (The laws are a bit more complicated than that, so you'll have to check it ;)

    To get the signal to your antenna from say a Linksys WRT54GL router, you would screw off the little pigtail, and connect that antenna connector, via cable, to your antenna on the mast. You lose a LOT of signal through this cable, the connectors used, etc., so you want to use good cable (like LMR195) AND keep the cable as short as possible. A way to do that, is to mount your WRT in a watertight (but not too small, as you have some heat) enclosure on the mast near the antenna, and then run power and a UTP cable down from the WRT to your laptop or network in the cabin. (You can also run network and power over the same UTP - search Power over Ethernet [PoE]).
    Dunno if lightning is a factor on a boat, but keep that in mind w.r.t. cables etc.

    Once you have your WRT54GL, you should load 3rd party firmware like Tomato, which would allow you to (i) scan for APs, (ii) focus your antenna based on signal strength received from the distant AP, (iii) set your WRT in the correct mode to function as a wireless client, and (iv) play with the transmit power and other settings when needed. Stock firmware can't do this.

    I seem to recall that somebody on this site did a boat thing, so search this site.
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