CHART ACCURACY
CHART ACCURACY BY NAUTICAL AREAS FROM THE IHO ( International Hydrographic Organization )
Maritime chart accuracy is crucial for safe and efficient navigation. Accurate charts provide essential information about water depths, hazards, and navigational aids, enabling mariners to plan voyages and avoid potential dangers. This accuracy directly impacts the safety of vessels and crew, the protection of marine environments, and the overall efficiency of maritime operations
| Country / Territory | Typical Near‑Shore ZOC | Likely Accuracy Level | Notes |
|---|---|---|---|
| Anguilla | B / C | Medium–poor | Some UKHO offshore surveys; nearshore gaps remain |
| Antigua & Barbuda | B / C | Medium–poor | UKHO modern sonar offshore, limited coastal detail |
| Aruba | A2 / B | High–medium | Dutch surveys cover main ports well |
| Bahamas | A2 / B | High–medium | Commercial channels better than inter-island shallow zones |
| Barbados | B | Medium | General survey coverage; limited recent coastal data |
| Belize | B / C | Medium–poor | Some recent work near Belize City, older data offshore and reef zones :contentReference[oaicite:2]{index=2} |
| Cayman Islands | A1 / A2 / B | High–medium | Strong port and harbor survey coverage |
| Cuba | B / C | Medium–lower | National HO data uneven; some older sketch surveys |
| Curacao | A2 / B | High–medium | Offshore and port zones well surveyed |
| Dominica | B / U | Medium–unassessed | Limited hydrographic resources; some offshore data missing |
| Dominican Republic | B / C / U | Medium–poor / unassessed | Spotty coastal coverage; gaps in many areas |
| Grenada | B | Medium | Port approaches surveyed; limited nearshore resolution |
| Guadeloupe | B / C | Medium–poor | French surveys offshore stronger than coastal zones |
| Haiti | C / U | Poor / unassessed | Hydrographic coverage limited; many areas unassessed |
| Jamaica | B / C | Medium–poor | Old coastal surveys; infrequent updating |
| Martinique | B | Medium | Some French coastal survey data; older scale maps |
| Montserrat | B | Medium | UKHO mapped offshore; nearshore data limited |
| Puerto Rico & USVI | A2 / B | High–medium | NOAA/NGA surveys; good coastal confidence in many areas |
| Saba, Sint Eustatius & Sint Maarten | B / C | Medium–poor | Dutch/Caribbean HO data moderate |
| Saint Kitts & Nevis | B | Medium | Some UKHO survey support; missing shallow-water detail |
| Saint Lucia | B / C | Medium–poor | Spotty depth coverage; ports better than open coast |
| Saint Vincent & the Grenadines | B | Medium | Port areas surveyed; islands and reefs less detailed |
| Suriname | B / C | Medium–poor | Government ENC production expanding; gaps offshore |
| Trinidad & Tobago | B / C | Medium–lower | Industrial port zones better than open shelf |
| Turks & Caicos | B / C | Medium–poor | Limited coastal resolution; offshore better charted |
SOUTH PACIFIC CHART ACCURACY
| Country / Territory | IHO Grade | Overall Quality | Notes |
|---|---|---|---|
| Australia | B | Medium–poor | ~45 % adequately surveyed; significant resurvey & unsurveyed areas |
| Fiji | C | Poor | ~25 % adequate; majority requires resurvey or never surveyed |
| Kiribati | C | Poor | 0 % adequate; fully unsurveyed by modern standards |
| New Caledonia (France) | A | Good | ~100 % adequate; best coverage in region |
| New Zealand | B | Medium | ~30 % require resurvey; ambiguity in adequacy reporting |
| Papua New Guinea | A | Good | ~72 % adequately surveyed; strongest among Pacific islands |
| Solomon Islands | C | Poor | ~60 % adequate; ~30 % require resurvey; many unsurveyed |
| Tonga | C | Poor | 0 % adequate; ~90 % require resurvey or unsurveyed |
| Tuvalu | C | Poor | ~60 % adequate; ~90 % unsurveyed or need resurvey |
| Vanuatu | C | Poor | ~40 % adequate; large resurvey gap (~55 %) |
| Samoa | C | Poor | Limited modern survey; largely unsurveyed or old coverage |
| Cook Islands | C | Poor | Minimal modern bathymetry coverage reported |
| Niue | C | Poor | Minimal hydrographic survey coverage |
| Wallis and Futuna | C | Poor | Very limited or no modern survey data |
| American Samoa | A | Good | NOAA-managed; Pago Pago Harbour likely meets Special / Order 1a quality |
| French Polynesia | C | Poor | Patchy and outdated surveys in many areas |
| Pitcairn Islands | C | Poor | Virtually no modern surveys; highly limited data |
| Galápagos (Ecuador) | B | Medium–poor | Ports partly surveyed; offshore mostly Order 2 or older data |
SOUTH AMERICA
| Country | IHO Grade | Overall Quality | Notes |
|---|---|---|---|
| Argentina | B | Medium | ~40–45 % adequately surveyed; southern channels partially modernized, offshore needs resurvey |
| Brazil | B | Medium | ~30–40 % adequate; major ports and shipping lanes modern, Amazon delta poorly charted |
| Chile | A | Good | ~70 % adequate; SHOA maintains modern surveys in ports, Patagonian channels, fjords |
| Colombia | B | Medium | ~30 % adequate; Caribbean ports modern, Pacific coast largely outdated |
| Ecuador (mainland) | B | Medium–poor | ~25–30 % adequate; major ports (Guayaquil, Esmeraldas) surveyed, coastal areas mixed |
| Peru | B | Medium | ~30–40 % adequate; Callao & major ports modern, offshore data older |
| Uruguay | B | Medium | ~40 % adequately surveyed; Montevideo and Río de la Plata approaches updated |
| Venezuela | C | Poor | <10 % adequate; major ports surveyed, offshore and Orinoco Delta outdated or unsurveyed |
| French Guiana | B | Medium–poor | Limited SHOM coverage; Kourou approaches adequate, rest Order 2 or older |
| Suriname | C | Poor | Minimal modern bathymetry; coastal charts largely reconnaissance quality |
| Guyana | C | Poor | Very limited survey coverage; mostly based on early lead-line data |
| Falkland Islands (UK) | B | Medium | Some modern UKHO coverage around Stanley; offshore largely Order 2 |
NORTH AND CENTRAL AMERICA
| Country / Territory | IHO Grade | Overall Quality | Notes |
|---|---|---|---|
| United States (continental) | A | Good | NOAA maintains full modern coverage; ports & approaches Special / Order 1a |
| Canada (Atlantic & Pacific) | A | Good | Canadian Hydrographic Service with ~70% adequate surveys; Arctic coasts less covered |
| Mexico (Pacific & Gulf) | B | Medium | ~30–40% adequate; major ports surveyed, many offshore areas outdated |
| Belize | B / C | Medium–poor | Main channels charted; reefs & outer atolls often based on older data |
| Guatemala | C | Poor | Minimal modern hydrographic work; mostly reconnaissance surveys |
| Honduras | C | Poor | Coastal charts mostly outdated; Bay Islands partially surveyed |
| Nicaragua | C | Poor | Limited modern survey; many coastal areas unsurveyed |
| Costa Rica | B / C | Medium–poor | Some port areas charted; Pacific coast lacks modern bathymetry |
| Panama | B | Medium | Canal & main ports modern; Caribbean and Pacific coasts less reliable |
| El Salvador | C | Poor | Very limited modern coverage; charts largely based on old surveys |
| Bahamas | B | Medium | Main channels updated, many shallow banks & cays outdated or based on Lidar |
| Cuba | B | Medium | Ports charted; offshore reefs often rely on Soviet-era data |
| Dominican Republic | C | Poor | Minimal modern surveys; some port approaches improved |
| Haiti | C | Poor | Almost no modern hydrography; charts based on early 20th-century data |
| Jamaica | B / C | Medium–poor | Kingston Harbor modern; outlying coasts outdated |
| Puerto Rico (US) | A | Good | NOAA coverage with modern Special / Order 1a surveys |
| Turks & Caicos | B / C | Medium–poor | Limited coastal resolution; offshore better charted |
| Cayman Islands (UK) | B | Medium | Main harbors modern; offshore deep areas Order 2 |
MEDITERRANEAN
| Country / Territory | IHO Grade | Overall Quality | Notes |
|---|---|---|---|
| Spain (Mediterranean coast & Balearics) | A | Good | IH Spanish Hydrographic Office maintains modern Special / Order 1a surveys in ports and approaches |
| France (Mediterranean & Corsica) | A | Good | SHOM coverage; ports, channels, and approaches fully modernized |
| Italy (mainland & islands) | A | Good | IIM surveys; major ports and coastal routes Special / Order 1a |
| Monaco | A | Good | Fully modern hydrographic coverage due to SHOM collaboration |
| Malta | A | Good | Comprehensive modern surveys; Valletta harbor Special Order |
| Greece | B | Medium | Main shipping routes and Piraeus well surveyed; many islands & Aegean approaches older data |
| Turkey (Mediterranean coast) | B | Medium | Main ports and straits modern; many coastal areas outdated |
| Cyprus | B | Medium | Ports surveyed; offshore coastal shelves partially outdated |
| Albania | C | Poor | Limited modern survey; reliance on historical charts |
| Montenegro | B | Medium | Kotor Bay updated; other coastal zones less surveyed |
| Croatia (Adriatic) | A | Good | Extensive modern hydrographic coverage; major ports Special / Order 1a |
| Slovenia | A | Good | Short coastline fully modernized |
| Bosnia & Herzegovina | C | Poor | Small coastal stretch; outdated data, minimal surveys |
| Egypt (Mediterranean coast) | B | Medium | Ports & approaches (Alexandria, Port Said) modern; offshore data mixed |
| Libya | C | Poor | Very limited modern surveys; ports partially updated |
| Tunisia | B | Medium | Main ports updated; many coastal stretches require resurvey |
ATLANTIC ISLANDS
| Country / Territory | IHO Grade | Overall Quality | Notes |
|---|---|---|---|
| Azores (Portugal) | A | Good | IHPT maintains modern surveys in main ports and approaches; offshore generally Order 2 |
| Madeira (Portugal) | A | Good | Modern multibeam surveys in Funchal & approaches; outer areas partially older data |
| Canary Islands (Spain) | A | Good | Modern Special / Order 1a in major ports; offshore shelves partially older Order 2 |
| Cape Verde | B / C | Medium–poor | Main ports surveyed; many islands and offshore areas outdated or reconnaissance quality |
| Ascension Island (UK) | B / C | Medium–poor | Georgetown harbor surveyed; offshore limited modern data |
| Saint Helena (UK) | B | Medium | Jamestown area modernized for new harbor; rest of coastline older data |
| Tristan da Cunha (UK) | C | Poor | Minimal hydrographic coverage; largely unsurveyed |
| Bermuda (UK) | A | Good | Modern NOAA/UKHO collaboration; Special / Order 1a in channels and harbors |
| Falkland Islands (UK) | B | Medium | Stanley harbor updated; much offshore still Order 2 |
| South Georgia & South Sandwich (UK) | C | Poor | Remote, mostly unsurveyed; limited reconnaissance around key anchorages |
NORTHERN EUROPE
| Country | IHO Grade | Overall Quality | Notes |
|---|---|---|---|
| Norway | A | Good | Extensive modern multibeam surveys; fjords & coastal shipping lanes Special / Order 1a |
| Sweden | A | Good | Swedish Maritime Administration maintains full modern coverage in major ports & archipelagos |
| Finland | A | Good | Nationally managed Special / Order 1a in Gulf of Finland and key routes; outer archipelago partly older Order 2 |
| Denmark | A | Good | Danish Hydrographic Office maintains modern charts in all shipping lanes and ports |
| Germany (North Sea & Baltic) | A | Good | BSH maintains Special / Order 1a in main ports and shipping channels; offshore Order 2 |
| Netherlands | A | Good | Modern hydrographic coverage; Wadden Sea and approaches fully resurveyed |
| Belgium | A | Good | Small coastline; fully modernized port and approaches |
| United Kingdom | A | Good | UKHO maintains extensive Special / Order 1a coverage; some Scottish west coast gaps improving |
| Ireland | B | Medium | Main ports and routes modernized; much west coast and offshore shelf older Order 2 |
| Iceland | B | Medium | Main harbors modern; significant offshore areas require resurvey |
| Faroe Islands (DK) | B | Medium | Main ports surveyed; many fjords and offshore approaches older data |
| Greenland (DK) | C | Poor | Vast areas unsurveyed; only key harbors and approaches covered |
🧭 Interpretation Guide: ZOC Categories
From IHO S‑67 and S‑57:
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A1 (6★): Very high accuracy — ± 5 m horizontal, depth tolerance ~0.5 m (95% CI); full seafloor search
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A2 (5★): High accuracy — modern surveys with multi‑beam or mechanical sweep; good depth precision but slightly less positional accuracy than A1
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B (4★): Medium accuracy — modern echo sounder surveys without full sweep; position ± 50 m, depth up to ~2 m variance; uncharted hazards unlikely but possible.
-
C / D (3★ or fewer): Poor accuracy or unassessed — limited or opportunistic data; positional variance up to 500 m, depth anomalies expected; hazards may not be charted
⚠️ Key Considerations for Mariners
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Many Caribbean areas still rely on older or opportunistic surveys, especially around smaller islands or remote locations.
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The Mach‑Caribbean ENC scheme (MACHC region) shows coverage gaps and inconsistent ENC scales or navigational purposes across different providers
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Always activate the ENCs “ZOC” display in ECDIS to visualize CATZOC ratings before planning or changing routes (especially important nearshore).
- In ZOC B or lower areas, adopt higher safety margins for under‑keel clearance and cross‑track distance; assume possible uncharted depth featu
