Chart Work
Capt. Priya Ranjan ■ Symbols and Various Other Topics
What is Wreck?
A shipwreck is the wreckage of a ship that is located either beached on land or
sunken to the bottom of a body of water.
Cartographers place these onto charts to warn large ships or commercial
fishing vessels to take extra care.
What is Wreck?
What is Wreck?
Detour Around These Dotted Wrecks!
Look for fishbone symbols enclosed by dots (middle illustration). Dots around
a wreck always indicate danger.
These wrecks are close enough to the surface to threaten all vessels.
Note the dangerous wreck to the north has no description.
All parts of this dangerous wreck will stay below the sea surface, even at low
tide.
Look at the dangerous wreck to the south and you see the abbreviation "Mast"
in slanted letters has been placed next to the wreck symbol.
This wreck will show just its mast above the sea surface at low water.
Look in the title block of your nautical chart (the summary of information
located beneath or near the chart title) to find the low water datum specified
for your nautical or electronic chart.
What is Wreck?
What is Wreck?
Ships anchor with hundreds of feet of chain, so these deep sea wrecks could
foul an anchor.
If the big ship anchor gets stuck inside a wreck, the ship might find it
impossible to weigh (pull in) their anchor.
And huge commercial fishing trawlers sometimes drag their nets along the
seabed.
These deep water wrecks could snag a net.
This could cause great danger and "trip" the fishing vessel (capsize it).
Or the fishing vessel skipper would have to cut away the net, costing him or
her tens of thousands of dollars in lost gear and equipment.
What is wreck?
Which Wrecks are Safe to Sail Across?
If you see just a fish-bone symbol without dots (far left illustration), this
means the wreck will be safe to cross.
You can draw a sailing course line across bare fish-bones all day long without
worry.
Note the two fishbone symbols southwest of lighted buoy "PP".
What is wreck?
What is Wreck?
Beware of Half-Hulls at the Surface
Stay far away from black hull symbols (far right illustration).
These wrecks show their deadly heads just above the surface at low water
datum (in some cases you will not see these until you are on top of them).
Half-hull symbols (Ajax Reef) signal a serious hazard. Stay well clear to avoid
catastrophe!
Note the slanted abbreviation "PA" next to the wreck.
This means "Position Approximate".
This wreck could shift position in storms, tidal surge or in high winds.
Note the small open circle with the vertical letters "pile" nearby.
Vertical letters tell you that this pile should be visible, even at high tide.
What is Wreck?
Beware of Half-Hulls at the Surface
Stay far away from black hull symbols (far right illustration).
These wrecks show their deadly heads just above the surface at low water
datum (in some cases you will not see these until you are on top of them).
Half-hull symbols (Ajax Reef) signal a serious hazard. Stay well clear to avoid
catastrophe!
Note the slanted abbreviation "PA" next to the wreck.
This means "Position Approximate".
This wreck could shift position in storms, tidal surge or in high winds.
Note the small open circle with the vertical letters "pile" nearby.
Vertical letters tell you that this pile should be visible, even at high tide.
What is Wreck?
What is Wreck?
What is Dumping ground at sea?
Marine Dumping has been defined as the deliberate disposal at sea of wastes
or other matter from vessels, aircraft, platforms or other man-made structures,
as well as the deliberate disposal of these vessels or platforms themselves.
Ocean Dumping. ... Dumping involves depositing all the waste materials from
factories and industries, tankers and ships and sewerage waste materials into
the oceans and seas.
Some of the materials emitted by the industrial wastes and sewage wastes
contain materials like mercury, cryolite and DDT
What is Dumping ground at sea?
What is a spoil area in the ocean?
Spoil areas as defined on charts and maps are simply the areas where the spoil has
been discarded.
Sometimes the spoil deposit will stand only a foot or two taller than the surrounding
sea floor, other times large islands will be formed of spoil material.
A "spoil area" is a location where approval has been granted to dump dredged
material.
When they deepen a channel, the stuff that comes off the bottom is known as
"dredged spoils".
What is a spoil area in the ocean?
What is a spoil area in the ocean?
What is a spoil area in the ocean?
What is a spoil area in the ocean?
What is Foul Ground on a chart?
Foul Ground is an area over which it is safe to navigate but which should be avoided
for anchoring, taking the ground or ground fishing
For example: remains of wreck; cleared platform.
What is Foul Ground on a chart?
What is Foul Ground on a chart?
What is Foul Ground on a chart?
What are fish havens?
Fish havens are artificial shelters made up of rocks, rubble, subway cars, ships, airplanes,
specially designed concrete structures, and other objects placed on the sea floor to attract fish
and enhance their habitat.
They are often located near fishing ports or major coastal inlets.
Consisting of rigid materials and projecting above the bottom, they can impede surface
navigation and foul anchors.
Thus, all fish havens are labeled with the abbreviation "Obstn”.
The Corps specifies an "authorized minimum depth" for each, which is the shallowest depth to
which objects may project toward the surface.
What are fish havens?
What are fish havens?
“Fish haven,”
The "Fish Havens" are areas where artificial reef structure is allowed.
This is important from a commercial fisherman's standpoint--they don't want
to hang up nets or trawls on the obstructions.
On the other hand, no depths or bottom contours are "Guaranteed" because
artificial reefs are allowed.
Most places require a permit, both state and federal for reef formation.
What are fish havens?
“Fish haven,”
The fish haven designation means that commercial fishing activities are not
allowed in that area.
They are often located near fishing ports or major coastal inlets.
Indicates to deep draft vessels that there may be obstructions not on the chart.
Fish havens are artificial shelters to attract fish and enhance their habitat.
A circle is used to depict fish havens that are too small to show their actual
size on the nautical chart.
What is PA on nautical chart?
"PA" means Position Approximate, labelled next to objects that have a higher
margin of survey error than those indicated earlier.
"PD" means Position Doubtful and refers again to the position of the object.
Stay clear of any area on your navigation chart marked by these
abbreviations.
PA - Position Approximate.
PD - Position Doubtful.
What is PA on nautical chart?
What is PA on nautical chart?
Buoyage System
Buoyage System
Buoyage System
