2 seamanship secrets
If you’re using British Admiralty Charts, order Chart 5011, “Symbols and Ab-
breviations Used on Admiralty Charts,” from the United Kingdom Hydrographic
Offi ce (Tel: + 44 (0)1823 723366, e-mail: [email protected], website: http://www
.ukho.gov.uk/amd/standardNavigationalCharts.asp).
Chart No. 1 and Chart 5011 are not nautical charts, but they provide the keys
to interpreting virtually every printed or electronic nautical chart you are likely to
use. Let’s check out the must-knows from these amazing dictionaries of nautical
symbology. (Note: unless otherwise indicated, all symbols discussed apply to charts
throughout the world.)
Chart Tints and Coloring
A darker shade of blue could mean danger for you.
—Anonymous MarinerCartographers use fi ve color backgrounds on most nautical charts. Th ree of these
represent above-tide and intertidal land masses and two represent water areas.
(Some other colors are used on foreign charts, but for now, we will concentrate
on U.S charts.)
Buff. Most land areas show a dull yellowish color. Th is buff -colored
topography remains visible at all stages of the tide. Elevated regions, such as
cliff s and mountains, off er excellent visual and radar targets for landfall and
positioning.
Gold. Th is distinctive tint, which shows up as a darker hue of buff , indicates
highly developed areas. If you need repairs, reprovisioning, or just a night
on the town, lay your course for these areas.
Green. Look just inside, along, or just off any coastline. Green tinting indicates
areas that cover or uncover with the tide, such as marshland, mudfl ats,
sandbars, and oyster beds. At low tide such areas may or may not be visible;
they may remain covered on a higher-than-normal neap low tide (the
low tide at the time of the quarter moon, when low-water heights average
higher than normal). At high tide, however, they’re completely underwater.
Give green-tinted areas a wide berth.
White. White is the primary background color for deeper water. Th e white
areas on a chart indicate water deep enough for most small craft. Never
assume, however. Always check out any area you plan to travel to and make
sure it’s safe.
Blue. Blue denotes shoal water. Depths decrease as the shade of blue darkens.
Study the depth marked on the chart inside any blue-tinted area before
deciding to pass that way. Also examine the curve that oft en encloses an