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Frequently Asked Questions
1. How do I purchase a nautical chart?
CHS offers a wide range of products (both paper
charts and electronic charts)
and services for navigational needs of the commercial shipper.
Electronic Navigational Charts (ENCs) are distributed under the trademark
Digital Ocean®, by Nautical Data International,
Inc. (NDI), the official distributor of digital hydrographic products
for CHS.
CHS products are available from over 700 authorized
chart dealers across the country.
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2. What are notices to mariners?
Notices to Mariners
are bulletins, detailing newly discovered hazards to shipping, and changes
in aids to navigation such as lights and buoys. They are issued monthly
in collaboration with, and through the offices of the Canadian
Coast Guard.
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3. What is the
difference between a raster and vector electronic chart?
Many of the CHS marine charts are available in digital form (vector or
raster). The raster navigational charts (RNCs) are an electronic image of
the paper charts, and, as such, provide no more information than that
which is available on the paper chart. However, features on vector charts,
which CHS encapsulates as Electronic Navigational Charts (ENCs), can
contain additional attribution that is not available on the paper or
raster charts. For example, a wharf appears as an image on a raster chart,
but the vector system can identify it as a wharf and attach attributes to
the wharf, such as height, length, age, and ownership. This data might
otherwise be available only by consulting the relevant printed Sailing
Directions
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4. What is the difference between a hydrographic chart and a
topographic map?
A hydrographic chart (also known as a nautical chart or marine chart)
is specifically designed to meet the requirements of marine navigation
by showing the depths of water, the nature of the bottom, elevations,
configuration and characteristics of the coast, dangers, and aids to navigation.
A topographic map focuses on the horizontal and vertical positions and
features of the land. A topographic map uses contours or comparable symbols
to show mountains, valleys, and plains.
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5. Are there any nautical charts of my lake?
Unfortunately, the Canadian Hydrographic Service does not produce hydrographic
charts of many inland waters. Due to budget limitations we are restricted
to charting only some of the largest of Canada's inland waterways, as
well as our coastal waters.
However, a provincial agency may have charted the lake you are interested
in or they may know of some private company that has produced a chart.
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6. What is chart datum?
Chart Datum is the datum surface to which depths on a published chart,
all tide height predictions, and most water level measurements are referred.
On most Canadian coastal charts the lower low water, large tide, has been
adopted as chart datum. For non-tidal water, the chart datum is set during
low-stage years. (Source: Canadian Tidal Manual published by CHS).
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