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10 A fuse Installing DepthSounders, Weather
Systems, and Autopilots
D
epth sounders, weather monitoring systems, and autopilots are three areas in
marine electronics where we have seen dramatic improvements and increased
sophistication over the last ten years. Depth sounders and particularly fishfinders
have evolved from the old Si-Tex paper drum recording units that were a mainstay among
serious fishermen for some time to the full-color LCD display units of today. Side-
scanning and even forward-searching depth-sounding capabilities are now available for
those who feel the need for that level of underwater probing. As for weather monitoring,
the old wind vane and cup masthead sensors in use for decades are being replaced with
ultrasonic sensors that have no moving parts to wear out or get broken by errant seagulls.
Autopilots have gotten more powerful, and draw less electrical current than they used to,
enabling offshore cruisers to consider using electric autopilots instead of wind vane
controlled self-steering systems (which are always a concern due to battery capacity limi-
tations). They are now relatively easy to interface with GPS, thus not only automatically
steering your boat, but taking you where you want to go quite accurately.Depth Sounders
Depth sounders and fishfinders are echo-sounding systems used to determine the depth of
water under your boat or to find targets (many units combine the two systems). They are
similar to most of the devices discussed in Chapter 14 in that they have a display, transmit
and receive signals, and use cables. They are different in that instead of an antenna, depth
sounders have a transducer, which for most recreational systems transmits at a frequency
of 50 kHz or 200 kHz. (Lowrance—www.lowrance.com—recently began advertising
dual-frequency units transmitting at 80 kHz or 200 kHz.)
Depth sounders can be simple devices that only tell you the distance to the bottom or
they can be feature rich with, for example, various alarms (shallow/deep water, warning),
forward scanning, and the ability to provide pictures or a graphic contour of the bottom.
Some include SeaTalk or NMEA capabilities and can be networked to your autopilot,
GPS, radar, or chartplotter. They range in price from $100 to $3,500.CHAPTER
15
Copyright © 2007 by Edwin R. Sherman. Click here for terms of use.