As a metal boat owner, I don't have a choice. The boat looks like a series
of Faraday cages, with metal watertight doors pulled down against very thin
gaskets and all the thru bulkhead fittings of minimum size. There will be no
3" gaps; one of the advantages of metal is that you have a good chance of
keeping fire and flood in one compartment if you're careful.

Even if I had a choice, however, I'd probably stick with wire. A boat is
not a house or office. Aside from alternators, we have a variety of sources
of potential interference -- radios (150 watt sideband and 25 watt VHFs),
radar, and so forth. 802.11 "should" ignore all of that. But "should" is a
big word at sea. Although the 10baseT pairs could also act as antennas and
could pick up RFI, my instinct is that it's a safer choice.

As for using either the AC or DC lines, I have the same objection. And even
in relatively small boats, the AC system is usually split bus (so you can
plug in two 120V 30A lines to a dock), so you have to do some capacitive
coupling.

Of course in saying all of this, I do have the advantage that we're doing a
major refit, and it's very easy to lay in an extra conduit for the network
(actually it isn't even extra as we'll have a conduit for phone and
signaling anyway). Certainly if I were adding a network to an existing boat
that wasn't well set for easy access everywhere (that's another topic), I'd
certainly take a shot at using wireless and test the hell out of it at the
dock.


--
Jim Woodward
www.mvFintry.com


..
"Larry W4CSC" wrote in message
...
On Sat, 8 Nov 2003 00:36:32 +0100, "Meindert Sprang"
wrote:

"Larry W4CSC" wrote in message
...
Why do I keep dreaming of an 802.11g network interface on every piece
of electronics NMEA connects by wires, now? Hell, with broadband, I
could overlay the color radar display from the Raymarine right all the
computer screens aboard!

Well, do "steel hull" or "aluminum hull" ring a bell? Apart from that,
you
have to bring power to the electronics anyway, so whats wrong with an
extra
pair for data?

Meindert

The DC power is already in every space I ever install an instrument.
I don't have to pull a wire through the bilge or engine room or
overhead to get it. It's already there, plenty of it.

As for your comment about wireless in metal hulls, try running a 2400
Mhz WiFi in a steel hull. 2400 Mhz flows right through hatches and
other openings over 3" wide. But most people, here, don't have, or
more accurately, wouldn't have a metal hull. Your argument to defend
your turf is moot. Networking on metal boats could simply be added to
the DC circuitry, like the powerline routers are doing now....though
they'd have to operate above 24 Mhz to keep interference with the HF
radios down. We've fooled around with a powerline router system with
wall brick terminals that have Ethernet jacks on them, from Netgear.
Every AC jack on the dock becomes a wideband internet connection
across the marina. Works great! That could be added to the existing
AC or DC power lines in metal boats.....USING TCP/IP NETWORKING, not
some idiotic, proprietary protocol designed to prevent you from
hooking A company's equipment to B company's equipment....you
know....like we have now.




Larry W4CSC

"Very funny, Scotty! Now, BEAM ME MY CLOTHES! KIRK OUT!"