need a large chart table to open them out on.
They are not usually used in the cockpit.
Electronic Charts : The first electronic
charts were only available individually and to
move to another area you had to select another
chart. Fortunately we can now scroll seamlessly
from one chart to another with most plotters and
laptops. Garmin, C Maps, and Navionics are
perhaps the most popular providers although
there are others. As with paper charts, accuracy
is still an issue. When navigating in harbours or
close to land or reefs extra care is needed to
avoid grounding.
Chart Plotters : Electronic charts installed
on chart plotters can be fitted in the cockpit,
beside the helmsman and can be viewed day or
night. When linked to a GPS receiver they can
show your boat on the screen as you travel in
The Portland Plotter (the Breton Plotter is very similar)
real time. This visual display in the cockpit is very
reassuring and helpful. If your chart plotter also
has a radar display built in, you can overlay the
appear quite small. On a coastal radar information onto the chart. This is helpful to check the accuracy of the chart.
chart the minutes will appear much Any difference in the overlay picture would indicate an inaccurate chart. Some
longer, depending on the scale of the plotters are quite complex to operate, as they can show more than just charts and
chart. On a harbour chart there may perhaps radar. Tidal stream, height and time information is available. While some
be a separate scale for representing can show aerial photos of harbours, and 3D images of the land surrounding them.
distance.
In the UK the main provider of paper
charts is the British Admiralty. Admiralty
charts are available for most sea areas
of the world with few exceptions. As
well as charts for navel and commercial
use, they produce Leisure charts,
chart folios of popular areas and Tough
charts that are on special material that
will cope with water and rough usage.
Imray publish charts for areas where
yacht cruising is popular, eg the UK,
Caribbean and Mediterranean. Many
developed countries of the world
produce their own charts. Most of
these charts are of good quality but the
symbols differ occasionally. It is worth
remembering that the accuracy of all
charts should be treated with suspicion
as many were drawn using a sextant
to provide positional fixes, and not the
GPS system. In remote areas this is a
more common problem.
Raymarine’s popular E120 with (clockwise from top left) chart software, 3D chart
software display, on board camera display and visual depth sounder display all on
The main reason for using paper charts
one screen with the option to full screen any one item
is that they can still be used if all power
on board is lost. Or the electronic
plotter develops a fault. They also give Computers : Laptop computers can be loaded with chart management
an instant overview of the area they software, which will allow the laptop to be used on board in a similar way to a
cover, without the need to manipulate chart plotter. The same additional information is available as it is on the chart
the chart area on a chart plotter screen. plotters. Some of these programs will allow you to lay internet weather forecasts
The main disadvantages are that a large onto the chart display. Some chart management programs are very complex,
library of paper charts will be heavy and whilst some are more basic and easy to use. With the most basic systems only
perhaps awkward to store. They also charts may be available, without the extra information.
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JUNE 2009 : MULTIHULL REVIEW 19
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