SEAMANSHIP Words by Geoff Linter
Basic Navigation 
and Passage 
Planning
Navigation at sea is the process of planning and undertaking a
voyage from one location to another. The ability to navigate is a
fundamental part of good seamanship. As competent seamen in
today’s world we must learn to navigate with today’s technology,
with GPS systems, chart plotters or laptops. However, we must also
learn the basic skills of navigation on paper charts.
he Global Position finding System or GPS
T
has changed the way most navigators
keep aware of their vessel’s position.
Couple this with ever more sophisticated
Chart Plotters that show us our boat on the moving
chart display, and you have a seductive way of
navigating. However, as safety conscious seamen,
we must be careful not to put too much trust in this
incredible technology.
In the Bristol Channel not long ago the lifeboat was
called out to a yacht that had GPS failure. The skipper
was simply unable to navigate his way to a safe harbour
without it.
To navigate effectively at sea we will need an up to date
Chart Table onboard Geoff’s Ocean Twins
chart of the correct scale for the area we are sailing.
Simplistically there are two families of chart available to
us. Paper charts and electronic charts. A plastic instrument known as a Breton or Portland Plotter
incorporating a compass/direction feature is perhaps the
Paper Charts: These are available in various
easiest tool to use for chart plotting. Combine that with a
scales, with detailed harbour charts, coastal passage
pair of dividers for measuring distance, a soft 2B lead pencil,
making charts and large area charts covering oceans, or
and a hand bearing compass and you have the tools for
perhaps the entire UK. All have their uses. A Latitude
paper chart navigation.
and Longitude reference is normally printed around the
edges, enabling us to “fix” our position on the chart if we
All of the charts will contain a large amount of information.
know our current Lat and Long, perhaps from the GPS.
Often in symbol form and it is important to be able to decode
We could also plot our position by taking compass
the symbols. This allows us to know where to find rocks,
bearings from conspicuous objects on land that are
wrecks, overfalls and so on…. The Admiralty produce a
also shown on the chart. Perhaps a church spire or
chart 5022 that is in book form. This decodes the symbols
gas tower. Drawing three bearing lines on the chart that
for us. In order to measure the distance on the chart we
converge, will often form a small triangle known as a
use the latitude scale down the side. One degree of latitude
“cocked hat” with our estimated position (EP) within that
contains sixty parts, or minutes. Each minute equals one
triangle.
nautical mile. On an overview chart these minutes will
18  MULTIHULL REVIEW : JUNE 2009
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