ELECTRONICS
Channels 1 through 11 are currently available for use by
wi-fi networks using the 802.11b or 802.11g standard.
Devices using the 802.11g standard operate with a
maximum speed of 54 megabits per second (Mbps),
while those using 802.11b are limited to a top speed of
11Mbps. As a comparison, the maximum data rate for a
dial-up Internet connection is 54kbps; a cable modem
peaks at 20Mbps. But the maximum raw-data transfer
rates for these connections can be misleading. Due to
the overhead required for processing, a typical useful
data transfer rate or throughput is almost always less
than the maximum rating. For a wi-fi connection, expect
about 4.3Mbps for networks utilizing the 802.11b
standard and 19Mbps when 802.11g is used. A radio
signal transmitted on a frequency of 2.4GHz is more
or less limited to line-of-sight signal paths between the
transmitter and the receiver. Signals at this frequency
will penetrate some distance through wood, plastic,
and other nonmetallic substances, but not without being
diminished in strength. This doesn’t mean that a
wi-fi signal can penetrate the earth’s surface or travel
underwater, but it will usually pass through a fiberglass
or wood boat structure, even though it will suffer some
loss in strength in the process. Wi-fi transmissions on
the 2.4GHz ISM band are limited to a maximum of
1 watt, but most wi-fi adapters operate well below
this constraint.
THE MARINA WI-FI ENVIRONMENT
A typical marina environment is tough on wi-fi
signals. The signal path is littered with masts, light
posts, and the structures of surrounding boats. From a
radio standpoint, it’s often full of noise and interference
produced by everything from engine alternators to
microwave ovens to other networks. The usual approach
is to place a laptop with a built-in wi-fi adapter on the
chart table below decks; however, this often produces
frustratingly marginal results at best. In theory, a weak
wi-fi signal should be as good as a stronger one, but, as
a rule, the reality is somewhat different. Weak signals
have the irritating habit of dropping out occasionally,
usually at some critical juncture, causing the connection
to be lost for a few moments. Even if the connection
is reasonably steady, the operating speed of a weak
