Boating and Sailing.pdf - Moja ladja

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Part 3: Getting from Point A to Point B: Marine Navigation
In Living Color
You can also view the depths in color. Cathode Ray Tubes (CRTs) are not space guns but
color depth finders. They function much like a small television set and are about as big—
the box on these machines is three to six times larger than a typical LCD. That size factor
kept them out of most small recreational boats as did the price, from $1,000 and up.
Fortunately, recent tech advances now provide LCD color depthfinders/GPS units that
are much smaller than CRTs. In fact, they’re about the size of black and white LCD
machines but with far more features. They’re still fairly costly; prices start at around
$1,100, but if you’re serious about bottom-fishing, you’ll want one.
The nice thing about color units is that they show different colors for bottom, bait, and
gamefish, making it easy to sort things out at a glance, even when traveling fast. The
screens are much brighter than black and white LCDs, too, making it easier to read them
in sunlight.
A Handy Extra: Radio Direction Finders
Radio Direction Finders (RDFs) are a useful extra tool for those who spend a lot of time
offshore and frequently make long coastal cruises where a backup to the GPS is a great
comfort.
RDFs are basically moveable radio antennas that provide readouts indicating the direction
from which the strongest and weakest signal on a given station comes. Using this information
and a marine chart that lists the location of the broadcasting station, boaters can
determine lines of position (LOPs). Do it for two or more stations and you have the location
of your boat where the LOPs cross.
Radar Shows It All
Radar is rarely used on smaller recreational boats because its high cost ($1,500 to $3,000),
but on larger boats used regularly offshore and in inclement weather, it’s a basic part of
the navigational tool kit. Radar is similar to sonar, but it operates above the surface and
sends out radio waves rather than sound pulses to measure distance.
Radar can draw the shape of a coastline, show the presence of other boats ahead, and
measure both distance and bearing to anything appearing on the screen. It’s a great asset,
particularly at night or in low visibility.