Shom C Nautical Chart – Antarctic Ocean

The Shom C nautical chart is a flat paper chart, generally supplied rolled, designed for navigation and route planning in the southern regions covered by the French Hydrographic and Oceanographic Service (Shom). It is particularly relevant to the Southern Ocean, approaches to Antarctica, the French Southern and Antarctic Lands, and the maritime areas surrounding the Antarctic continent.

Navigating in the Antarctic Ocean

Navigation in Antarctic waters presents very specific challenges. Distances are enormous, weather conditions can change rapidly, sea ice and icebergs can affect navigation, coastlines are often difficult to access, and port infrastructure is extremely limited.

Selecting the appropriate nautical chart therefore requires careful consideration of the geographical area, the scale of the chart, the intended type of navigation and the areas through which the vessel will travel.

A Shom C chart provides a paper representation of the maritime environment, including soundings, depth contours, shoals, rocks, reefs, wrecks, channels, navigable passages, aids to navigation, lights, landmarks, ports, installations, anchorages and other information required for marine navigation.

Shom C format for long-distance navigation

The Shom C chart is a flat paper chart, generally supplied rolled in a protective tube. This format is particularly suitable for large-scale route planning on a chart table and for long-distance voyages.

Depending on the geographical area, Shom C charts can be used to prepare routes linking the southern Atlantic, southern Indian Ocean and southern Pacific Ocean with the waters surrounding Antarctica.

They can therefore be relevant to voyages departing from or approaching:

• southern Argentina and Tierra del Fuego;

• the Falkland Islands;

• southern Africa;

• the southern Indian Ocean;

• southern Australia and Tasmania;

• New Zealand;

• Terre Adélie;

• the Antarctic Peninsula;

• the Ross Sea and other Antarctic regions.

The choice of chart should always be based on the intended route and the scale required for the different phases of navigation.

The Southern Ocean

The Southern Ocean surrounds Antarctica and connects the southern parts of the Atlantic, Indian and Pacific Oceans. It forms the principal maritime environment between the temperate southern latitudes and the Antarctic continent.

For vessels approaching Antarctica, routes may originate from South America through the Drake Passage, from southern Africa through the southern Atlantic and Indian Oceans, or from Australia and New Zealand towards the Ross Sea.

The geographical extent of the Southern Ocean means that a single chart is rarely sufficient for an entire voyage. General or offshore charts are useful for the overall route, while larger-scale charts are required when approaching coastlines, islands, straits, channels, stations or anchorages.

Terre Adélie and the French Antarctic sector

Terre Adélie is an important French Antarctic sector. The Dumont-d’Urville station is located on Île des Pétrels, within the Pointe-Géologie archipelago.

The surrounding waters include the Somov Sea, the D’Urville Sea and the maritime areas off the coast of Terre Adélie.

For a voyage approaching the French Antarctic sector, the choice of nautical chart must take into account the scale required for offshore navigation as well as the more detailed requirements associated with approaching the coast, islands, channels and installations.

A Shom chart can therefore form part of the overall cartographic documentation used for route preparation towards Terre Adélie.

French Southern and Antarctic Lands

The southern Indian Ocean is also an important area for French maritime and scientific navigation. The French Southern and Antarctic Lands include several isolated island groups, including:

• the Kerguelen Islands;

• the Crozet Islands;

• Amsterdam Island;

• Saint-Paul Island.

Port-aux-Français, located on the Kerguelen Islands, is an important scientific and logistical base. It should not be confused with a conventional commercial port.

On the Crozet Islands, the Alfred-Faure station on Possession Island is another important scientific base.

Because these islands are isolated and exposed to demanding weather conditions, navigation requires careful preparation and appropriate chart scales. Offshore charts may be combined with larger-scale coastal and approach charts depending on the route.

Antarctic Peninsula and Weddell Sea

The Antarctic Peninsula is one of the most accessible Antarctic regions from South America. Voyages generally cross the Drake Passage before reaching the South Shetland Islands, the Bransfield Strait and the Antarctic Peninsula.

The Weddell Sea lies to the east of the Antarctic Peninsula and is characterized by extensive areas of sea ice and demanding navigation conditions.

Depending on the route, navigation may involve:

• the Drake Passage;

• the South Shetland Islands;

• the Bransfield Strait;

• the Antarctic Peninsula;

• the Weddell Sea;

• channels between Antarctic islands;

• coastal approaches and anchorages.

Ushuaia in Argentina and Punta Arenas in Chile are major departure and support points for Antarctic voyages. They are not Antarctic ports themselves but are important logistical bases for vessels preparing to cross towards the Antarctic Peninsula.

Access from Australia and New Zealand

Australia and New Zealand provide another major access route towards Antarctica.

Hobart in Tasmania, Christchurch and Dunedin in New Zealand are important logistical and maritime departure points for voyages towards the Ross Sea and other Antarctic sectors.

Routes may lead towards:

• the Ross Sea;

• Ross Island;

• McMurdo Sound;

• Scott Base;

• McMurdo Station.

The geographical distance between these regions makes appropriate offshore and general charts particularly important during the initial stages of route planning.

Information provided by a Shom C nautical chart

A Shom C paper chart can contain a wide range of hydrographic and navigational information, including:

• soundings and depth information;

• depth contours;

• shoals and shallow areas;

• rocks and reefs;

• wrecks;

• channels and navigable passages;

• aids to navigation;

• lights and light characteristics;

• landmarks;

• ports and maritime installations;

• anchorages;

• restricted or regulated areas;

• geographic information required for route planning.

The chart should be read together with the relevant nautical publications and current navigational information.

Sea ice and icebergs

Sea ice is one of the major factors affecting navigation around Antarctica.

It is important to distinguish between different types of ice, including:

• pack ice;

• ice fields;

• icebergs;

• growlers and smaller fragments of floating ice;

• seasonal ice zones.

Ice conditions can change rapidly and are not necessarily represented on a nautical chart in real time. A nautical chart provides hydrographic and geographic information; current ice conditions require additional, up-to-date sources.

For this reason, Antarctic voyage preparation generally combines nautical charts with weather information, ice information, current data, local navigation information and appropriate nautical publications.

Choosing the appropriate chart scale

Scale is particularly important when planning an Antarctic voyage.

A small-scale chart can be used to obtain an overview of a large area of the Southern Ocean and to plan an offshore route over hundreds or thousands of nautical miles.

Larger-scale charts become necessary when approaching:

• the Antarctic coastline;

• islands and archipelagos;

• straits and channels;

• bays;

• anchorages;

• scientific stations;

• logistical installations;

• coastal navigation areas.

A complete voyage may therefore require several chart scales rather than a single nautical chart.

Shom C, Shom L, Shom G, Shom Z and Shom Raster

Shom format	Physical or digital format	Main characteristics	Typical use
Shom C	Paper, flat and generally rolled	Standard nautical chart	Offshore route planning and coastal navigation
Shom L	Paper, folded	Standard nautical chart, easier to handle and store	Coastal navigation and route planning
Shom G	Paper, folded	Nautical chart with additional sedimentological information	Study of seabed characteristics, fishing and professional applications
Shom Z	Paper, flat and generally rolled	Chart with a Zonex overlay showing exercise and firing areas	Navigation requiring awareness of military exercise areas
Shom Raster	Digital, GeoTIFF	Digital reproduction of a nautical chart	Use with compatible navigation and charting software

The different Shom formats are complementary rather than interchangeable. The appropriate choice depends on the vessel, the navigation system, the geographical area and the stage of the voyage.

Shom Raster digital nautical charts

The Shom also provides digital raster nautical charts in GeoTIFF format. These are digital images derived from nautical charts and can be used with compatible software.

Shom raster products are georeferenced and use WGS84 and Mercator projection. The available scales cover several levels of navigation, from general and ocean passages to coastal areas, ports and anchorages.

For Antarctic route preparation, digital charts can therefore complement paper charts and other navigational documentation.

Preparing an Antarctic voyage

A long-distance voyage towards Antarctica should be prepared using several types of documentation.

Depending on the route, the preparation may include:

• general charts covering the Southern Ocean;

• offshore passage charts;

• coastal charts;

• charts of islands and archipelagos;

• charts of straits and channels;

• charts covering approaches to scientific and logistical stations;

• information concerning sea ice;

• sailing directions;

• nautical atlases;

• navigational guides;

• relevant notices and corrections.

The chart portfolio should be determined according to the complete route rather than solely according to the final destination.

Main ports and navigation points

Several ports and maritime bases can play an important role in Antarctic route planning:

• Ushuaia, Argentina;

• Punta Arenas, Chile;

• Port Stanley, Falkland Islands;

• Cape Town, South Africa;

• Hobart, Australia;

• Christchurch, New Zealand;

• Dunedin, New Zealand;

• Port-aux-Français, Kerguelen Islands;

• Dumont-d’Urville, Terre Adélie;

• McMurdo, Ross Sea.

These locations do not all have the same function. Some are conventional ports, while others are scientific or logistical bases with very different access conditions.

How to choose a Shom C Antarctic nautical chart

When selecting a Shom C chart for an Antarctic voyage, several criteria should be considered:

• the geographical area covered;

• the planned route;

• the departure and destination points;

• possible stopovers;

• the chart scale;

• straits and channels along the route;

• areas potentially affected by sea ice;

• coastal approaches;

• anchorages;

• the chart edition and correction status;

• complementary nautical publications;

• the availability of additional weather and ice information.

For a long-distance Antarctic voyage, chart selection should be considered as a coherent set covering all stages of navigation.

Conclusion

The Shom C Antarctic nautical chart is a flat paper chart, generally supplied rolled, designed for route planning and navigation in the Southern Ocean, around Antarctica and in the southern maritime regions covered by Shom.

It is particularly relevant to voyages involving Terre Adélie, the French Southern and Antarctic Lands, the Antarctic Peninsula, the Weddell Sea, the Ross Sea and the major maritime approaches to Antarctica.

Because Antarctic navigation involves enormous distances, rapidly changing weather, sea ice, icebergs and limited coastal infrastructure, selecting the appropriate chart scale is essential.

A Shom C chart should therefore be considered as one component of a complete navigational portfolio, alongside appropriate coastal and approach charts, nautical publications, atlases, weather information, ice information and other current navigational data.

Frequently Asked Questions

What is a Shom C Antarctic nautical chart?

A Shom C Antarctic nautical chart is a flat paper nautical chart, generally supplied rolled, designed for route planning and navigation in the Southern Ocean, around Antarctica and in the southern maritime regions covered by Shom.

What is a Shom C chart used for?

It is primarily used for offshore route planning and navigation over large maritime areas. Depending on its scale, it can also contribute to coastal route preparation.

Which regions can be covered by Shom C Antarctic charts?

Depending on the chart, the coverage can include the Southern Ocean, approaches to Antarctica, Terre Adélie, the French Southern and Antarctic Lands, the Antarctic Peninsula, the Weddell Sea, the Ross Sea and other southern maritime regions.

Does a Shom C chart cover Terre Adélie?

Shom nautical chart coverage includes French Antarctic maritime areas. The appropriate chart and scale depend on the specific route and geographical sector concerned.

Which ports are commonly used for Antarctic voyages?

Ushuaia and Punta Arenas are major departure and logistical points for voyages towards the Antarctic Peninsula. Hobart, Christchurch and Dunedin are important access points for routes towards the Ross Sea. Cape Town can also serve as a southern maritime departure point depending on the voyage.

What is the Southern Ocean?

The Southern Ocean surrounds Antarctica and connects the southern sectors of the Atlantic, Indian and Pacific Oceans. It is the principal maritime environment surrounding the Antarctic continent.

Why is sea ice so important for Antarctic navigation?

Sea ice, icebergs and other forms of floating ice can affect route selection, access to coastal areas and the safety of navigation. Conditions can change rapidly, so current ice information must complement the nautical chart.

What is the difference between a Shom C and a Shom L chart?

Both are paper nautical charts. Shom C charts are generally supplied flat and rolled, whereas Shom L charts are folded. The choice depends mainly on handling requirements, storage and the intended use of the chart.

What is a Shom G chart?

A Shom G chart is a nautical chart containing additional sedimentological information concerning seabed characteristics. It can be particularly useful for applications requiring information about seabed sediments.

What is a Shom Z chart?

A Shom Z chart includes a specific overlay showing military exercise and firing areas. Such information is important when planning navigation through potentially regulated maritime areas.

What is a Shom Raster chart?

A Shom Raster chart is a digital raster representation of a nautical chart. Shom digital raster products are available in GeoTIFF format and are intended for use with compatible software.

Is one chart sufficient for an Antarctic voyage?

Usually not. The enormous distances involved mean that several chart scales and geographical areas may be required, from general offshore charts to larger-scale coastal and approach charts.

Which complementary documents should be used?

Depending on the voyage, complementary documentation may include sailing directions, nautical atlases, navigational guides, current notices, weather information, ice information and other official navigational publications.