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"GPS Instant Navigation"
is aptly described in its title. The book is intended
as a tool for skippers, who can use it to plan route
selection, plot waypoints and adapt them to electronic
charting.
Written by Kevin Monahan (a Canadian coast guard officer
with over 20 years’ experience) and Don Douglass
(a longtime cruiser of the Northwest) this reference
book starts with basics of navigation and leads, chapter
by chapter, to more advanced concepts and techniques.
The book touches on waypoint realization, understanding
GPS accuracy and navigating using differential GPS (DGPS).
Information in the book is so current that it even touches
on the U.S. Department of Defense’s removal of
selective availability in May of this year. The book
retails for $29.95.
Dear FineEdge.com,
I wonder if you could answer a question for me. I have
been trying to pinpoint some spots on a topo map but
the reference numbers (long/lat) I have been given I
don’t understand, e.g. 50.075 N, 125.742 W. The
positions are on land and I assume it (degrees/minutes/seconds)
works the same way as on the ocean. The numbers I found
were on the web site: www.for.gov.bc.ca/protect/LargeFires1999.htm
I have the book "GPS waypoints, British Columbia
Coast" but it could not help me on this matter.
Hope you can,
Adam
Dear Adam,
The coordinates from the web-site you visited are expressed
in decimal degrees. You ar probalby most familiar with
positions in degrees, minutes and seconds. To convert
decimal degrees to degrees and decimal minutes, you
simply multiply the portion of the latitude (or longitude)
after the decimal by 60. For instance 50.075N becomes
50 degrees plus (0.075 x 60) = 4.5 minutes. The latitude
then reads 50 degrees 04.5 minutes (or 50 degrees, 04
minutes, and 30 seconds).
However, when you try to plot the position on the topographical
map you will most likely encounter difficulties because
the map probably uses Universal Transverse Mercator
(or Military) grid coordinates, which use Northings
and Eastings. Our book "GPS Instant Navigation
(2nd Edition)" discusses UTM on page 48.
Check the topo map again to determine if it is marked
with degree or minute ticks in the margins. In most
cases topographical maps will only show whole minute
ticks in the margins--they normally do not show the
parts of a minute of latitude or longitude, so you will
have to interpolate to estimate the proper position.
The US Army Corps of Engineers has posted a free program
which converts between various coordinate systems. You
can obtain it at http://crunch.tec.army.mil/software/corpscon/corpscon.html
or you can perform the conversion using a GPS receiver.
Simply enter the lat/long co-ordinates as a waypoint,
and then change the display from NAD 27 (or NAD83) to
UTM coordinates. You should then be able to read the
UTM coordinates of the waypoint directly from the GPS
.
Thanks for you inquiry and good luck.
FineEdge
Kevin Monahan
To submit your review,
ask a question, or share your experience with this book,
Email: reviews@fineedge.com.
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