ENC Charts MCP Server

An MCP (Model Context Protocol) server for Electronic Navigational Charts (ENC) data, providing programmatic access to NOAA electronic navigational charts with S-57 format parsing capabilities.

Overview

This MCP server enables AI assistants to access and analyze electronic navigational charts from NOAA. It automatically downloads, caches, and parses S-57 format chart data, making it available through a standardized API. The server supports coordinate-based chart discovery, feature extraction, and navigation-focused queries.

Features

• S-57 Chart Parsing: Full support for IHO S-57 format electronic navigational charts
• NOAA Integration: Automatic chart discovery and downloading from NOAA REST APIs
• Coordinate-Based Queries: Find and retrieve charts based on GPS coordinates
• Smart Caching: Efficient local caching with configurable size and age limits
• Feature Filtering: Extract specific navigation features (lights, buoys, depths, etc.)
• 172 Object Classes: Complete support for S-57 object catalog
• Depth Analysis: Filter features by depth ranges for navigation safety
• Spatial Queries: Bounding box filtering for area-specific data

Prerequisites

• Node.js: Version 18 or higher
• Python: Version 3.7 or higher (for S-57 parsing)
• GDAL Python Bindings: Required for chart data parsing

Installation

Install the MCP server globally via npm:

npm install -g enc-charts-mcp

Installing GDAL Dependencies

The server requires GDAL Python bindings for S-57 chart parsing:

macOS:

# Using Homebrew
brew install gdal
pip3 install gdal==$(gdal-config --version)

Ubuntu/Debian:

sudo apt-get update
sudo apt-get install gdal-bin libgdal-dev
pip3 install gdal==$(gdal-config --version)

Windows:

# Using conda (recommended)
conda install -c conda-forge gdal

Verify Installation

# Check if the server is installed
enc-charts-mcp --version

# Test GDAL availability
python3 -c "from osgeo import ogr; print('GDAL installed successfully')"

Configuration

Environment Variables

The server supports the following environment variables:

Variable	Description	Default
ENC_CACHE_DIR	Directory for chart cache	./cache/charts/
ENC_CACHE_MAX_SIZE_GB	Maximum cache size in GB	10
ENC_CACHE_MAX_AGE_DAYS	Cache expiration in days	7

Claude Desktop Integration

Add the following to your Claude Desktop configuration file:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "enc-charts": {
      "command": "npx",
      "args": ["enc-charts-mcp"],
      "transport": {
        "type": "stdio"
      },
      "env": {
        "ENC_CACHE_DIR": "~/.enc-charts/cache",
        "ENC_CACHE_MAX_SIZE_GB": "20",
        "ENC_CACHE_MAX_AGE_DAYS": "14"
      }
    }
  }
}

Note: Adjust the cache directory path based on your preferences. The server will automatically create the directory if it doesn't exist.

Quick Start

After installation and configuration, restart Claude Desktop. You can then use the ENC charts tools in your conversations:

1. Find charts for a location:

   Use the get_chart tool with coordinates: 
   lat: 37.8, lon: -122.5 (San Francisco Bay)
   

2. Search for charts in an area:

   Use search_charts with a bounding box to find all charts 
   between San Diego and Los Angeles
   

3. Get navigation features:

   Get all lights and buoys from chart US5CA12M
   

Available Tools

get_chart

Retrieve chart features for a specific area by chart ID or coordinates.

Parameters:

• chartId (string, optional): Chart identifier (e.g., "US5CA12M")
• coordinates (object, optional): GPS coordinates
  • lat (number): Latitude (-90 to 90)
  • lon (number): Longitude (-180 to 180)
• boundingBox (object, optional): Geographic bounds filter
  • minLat, maxLat, minLon, maxLon (numbers)
• featureTypes (array, optional): S-57 object classes to include
• depthRange (object, optional): Depth filter in meters
  • min, max (numbers)
• includeNearby (boolean, optional): Include nearby features
• limit (integer, optional): Maximum features to return (default: 100, max: 1000)
• offset (integer, optional): Number of features to skip for pagination (default: 0)

Example Request:

{
  "coordinates": { "lat": 37.8, "lon": -122.5 },
  "featureTypes": ["LIGHTS", "BOYLAT", "DEPARE"],
  "depthRange": { "min": 0, "max": 20 }
}

Example Response:

{
  "chartId": "US5CA12M",
  "features": [
    {
      "id": "LIGHTS.123",
      "type": "LIGHTS",
      "geometry": {
        "type": "Point",
        "coordinates": [-122.5295, 37.8156]
      },
      "properties": {
        "COLOUR": ["1"],
        "LITCHR": 8,
        "SIGPER": 4,
        "VALNMR": 18
      }
    }
  ],
  "featureCount": 42,
  "totalFeatures": 150,
  "hasMore": true,
  "limit": 100,
  "offset": 0,
  "source": "NOAA ENC"
}

search_charts

Search available charts by various criteria.

Parameters:

• query (string, optional): Search by name or area
• scale (object, optional): Scale range filter
  • min, max (numbers)
• boundingBox (object, optional): Geographic search area
• format (string, optional): Chart format ("S-57" or "S-101")
• limit (integer, optional): Maximum charts to return (default: 50, max: 100)
• offset (integer, optional): Number of charts to skip for pagination (default: 0)

get_chart_metadata

Get detailed information about a specific chart.

Parameters:

• chartId (string, optional): Chart identifier
• coordinates (object, optional): GPS coordinates to find chart

get_object_classes

Get information about S-57 object classes and their representations.

Parameters:

• category (string, optional): Filter by category
  • Options: "navAids", "depths", "areas", "infrastructure", "natural", "hazards"
• search (string, optional): Search by acronym or description
• includeAttributes (boolean, optional): Include standard attributes

Data Sources

NOAA ENC Online

The server integrates with NOAA's Electronic Navigational Chart services:

• XML Product Catalog: Charts metadata from https://www.charts.noaa.gov/ENCs/ENCProdCat.xml
• Chart Downloads: Individual S-57 format ZIP files from https://www.charts.noaa.gov/ENCs/
• Update Frequency: Weekly for most charts
• Coverage: US waters and territories
• No Authentication Required: All NOAA resources are publicly accessible

Charts are automatically downloaded on-demand when queried by coordinates and cached locally for performance. The XML catalog is cached for 24 hours to reduce API calls.

How It Works

1. Chart Discovery: The server queries NOAA's XML product catalog to find charts based on coordinates or search criteria
2. Automatic Download: Charts are downloaded on-demand from NOAA when requested
3. Local Caching: Downloaded charts are cached locally to improve performance
4. S-57 Parsing: Chart data is parsed from S-57 format using GDAL Python bindings
5. Feature Extraction: Navigation features (lights, buoys, depths, etc.) are extracted and returned as GeoJSON

S-57 Object Classes

The server supports all 172 standard S-57 object classes. Key categories include:

Navigation Aids

• LIGHTS - All lighted aids (lighthouses, beacons, lit buoys)
• BOYLAT - Lateral buoys (port/starboard markers)
• BOYSAW - Safe water buoys
• BCNLAT - Lateral beacons
• DAYMAR - Day marks

Depth Information

• DEPARE - Depth areas with ranges
• DEPCNT - Depth contour lines
• SOUNDG - Individual soundings
• DRGARE - Dredged areas

Areas & Boundaries

• FAIRWY - Navigation channels
• ANCHRG - Anchorage areas
• RESARE - Restricted areas
• TSSLPT - Traffic separation schemes

Hazards

• OBSTRN - Underwater obstructions
• WRECKS - Shipwrecks
• ROCKS - Rocks and reefs

Usage Tips

Efficient Chart Queries

1. Use Feature Filtering: Specify featureTypes to reduce response size
2. Apply Bounding Boxes: Limit geographic scope when possible
3. Leverage Pagination: Use limit and offset for large datasets
4. Cache Warming: Frequently accessed areas benefit from pre-downloading

Common Feature Types

• Navigation Aids: LIGHTS, BOYLAT, BOYSAW, BCNLAT
• Depths: DEPARE, DEPCNT, SOUNDG
• Hazards: OBSTRN, WRECKS, ROCKS
• Areas: FAIRWY, ANCHRG, RESARE

Common Use Cases

1. Navigation Planning

Find charts and extract navigation aids for route planning:

// Get charts for Golden Gate area
{
  "coordinates": { "lat": 37.8199, "lon": -122.4783 },
  "featureTypes": ["LIGHTS", "BOYLAT", "BOYSAW", "BCNLAT"],
  "includeNearby": true
}

2. Anchorage Analysis

Find suitable anchoring spots with depth information:

// Search for anchorages with specific depth range
{
  "chartId": "US5CA12M",
  "featureTypes": ["DEPARE", "ANCHRG", "SOUNDG"],
  "depthRange": { "min": 5, "max": 15 },
  "boundingBox": {
    "minLat": 37.8,
    "maxLat": 37.82,
    "minLon": -122.52,
    "maxLon": -122.5
  }
}

3. Hazard Detection

Identify navigation hazards in an area:

// Get all hazards near a route
{
  "coordinates": { "lat": 32.7157, "lon": -117.1611 },
  "featureTypes": ["OBSTRN", "WRECKS", "ROCKS", "UWTROC"],
  "includeNearby": true
}

4. Chart Discovery

Find all available charts for a region:

// Search charts between San Diego and Los Angeles
{
  "boundingBox": {
    "minLat": 32.5,
    "maxLat": 34.0,
    "minLon": -118.5,
    "maxLon": -117.0
  },
  "scale": { "max": 50000 }  // Detailed charts only
}

Troubleshooting

GDAL Installation Issues

"GDAL Python bindings not found"

• Ensure Python 3 is in your PATH
• Match GDAL versions exactly: pip install gdal==$(gdal-config --version)
• On macOS, use Homebrew: brew install gdal
• On Windows, use conda for easier installation

"Failed to parse S-57 chart data"

• Verify GDAL is properly installed: python3 -c "from osgeo import ogr"
• Check that Python 3 is in your PATH (the server specifically uses python3)
• Some charts may require newer GDAL versions
• Run npm run gdal:validate to check your installation

Claude Desktop Issues

Server not appearing in Claude

1. Ensure the package is installed: npm list -g enc-charts-mcp
2. Check your config file path is correct
3. Restart Claude Desktop after configuration changes
4. Verify the npx command works: npx enc-charts-mcp --version

"No charts found for coordinates"

• Verify coordinates are in US waters (NOAA coverage area)
• Check internet connection for NOAA API access
• Try different coordinates or use a known chart ID

Cache Issues

Clearing the cache

# Default cache location
rm -rf ~/.enc-charts/cache/*

# Or your custom cache directory
rm -rf $ENC_CACHE_DIR/*

Disk space issues

• Adjust ENC_CACHE_MAX_SIZE_GB in your config
• Charts can be 10-100MB each
• Consider storing cache on a drive with more space

Development

Running Locally

# Clone the repository
git clone https://github.com/tonybentley/enc-charts-mcp.git
cd enc-charts-mcp

# Install dependencies
npm install

# Build the project
npm run build

# Run in development mode (with hot reload)
npm run dev

# Run production build
npm start

Development Commands

• npm run dev - Run in development mode with hot reload
• npm run build - Build TypeScript to JavaScript
• npm run test - Run unit tests
• npm run test:e2e - Run end-to-end tests
• npm run test:all - Run all test suites
• npm run lint - Run ESLint
• npm run typecheck - Run TypeScript type checking
• npm run format - Format code with Prettier

GDAL Validation

• npm run gdal:detect - Check if GDAL is properly installed
• npm run gdal:validate - Validate GDAL installation and environment
• npm run test:integration:check - Verify GDAL before running integration tests

Performance Considerations

• Charts can be 10-100MB each
• Initial downloads may take time
• Cache warming recommended for frequently accessed areas
• Spatial queries optimized for bounding boxes

Pagination

To prevent response size issues, the get_chart and search_charts tools implement pagination:

• get_chart: Returns up to 100 features by default (max: 1000)
• search_charts: Returns up to 50 charts by default (max: 100)

Use the limit and offset parameters to page through large result sets:

// First page
{ "chartId": "US5CA12M", "limit": 100, "offset": 0 }

// Next page
{ "chartId": "US5CA12M", "limit": 100, "offset": 100 }

The response includes pagination metadata:

• totalFeatures or totalCount: Total number of available items
• hasMore: Boolean indicating if more results exist
• limit: Number of items returned
• offset: Number of items skipped

License

ISC

Source Code

The source code is available on GitHub.

Contributing

Contributions are welcome! Please open an issue or submit a pull request on GitHub.

Acknowledgments

• NOAA for providing free electronic navigational charts
• IHO for the S-57 standard specification
• GDAL contributors for S-57 format support