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:
-
Find charts for a location:
Use the get_chart tool with coordinates: lat: 37.8, lon: -122.5 (San Francisco Bay) -
Search for charts in an area:
Use search_charts with a bounding box to find all charts between San Diego and Los Angeles -
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 coordinateslat(number): Latitude (-90 to 90)lon(number): Longitude (-180 to 180)
boundingBox(object, optional): Geographic bounds filterminLat,maxLat,minLon,maxLon(numbers)
featureTypes(array, optional): S-57 object classes to includedepthRange(object, optional): Depth filter in metersmin,max(numbers)
includeNearby(boolean, optional): Include nearby featureslimit(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 areascale(object, optional): Scale range filtermin,max(numbers)
boundingBox(object, optional): Geographic search areaformat(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 identifiercoordinates(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 descriptionincludeAttributes(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
- Chart Discovery: The server queries NOAA's XML product catalog to find charts based on coordinates or search criteria
- Automatic Download: Charts are downloaded on-demand from NOAA when requested
- Local Caching: Downloaded charts are cached locally to improve performance
- S-57 Parsing: Chart data is parsed from S-57 format using GDAL Python bindings
- 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 buoysBCNLAT- Lateral beaconsDAYMAR- Day marks
Depth Information
DEPARE- Depth areas with rangesDEPCNT- Depth contour linesSOUNDG- Individual soundingsDRGARE- Dredged areas
Areas & Boundaries
FAIRWY- Navigation channelsANCHRG- Anchorage areasRESARE- Restricted areasTSSLPT- Traffic separation schemes
Hazards
OBSTRN- Underwater obstructionsWRECKS- ShipwrecksROCKS- Rocks and reefs
Usage Tips
Efficient Chart Queries
- Use Feature Filtering: Specify
featureTypesto reduce response size - Apply Bounding Boxes: Limit geographic scope when possible
- Leverage Pagination: Use
limitandoffsetfor large datasets - 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:validateto check your installation
Claude Desktop Issues
Server not appearing in Claude
- Ensure the package is installed:
npm list -g enc-charts-mcp - Check your config file path is correct
- Restart Claude Desktop after configuration changes
- 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_GBin 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 reloadnpm run build- Build TypeScript to JavaScriptnpm run test- Run unit testsnpm run test:e2e- Run end-to-end testsnpm run test:all- Run all test suitesnpm run lint- Run ESLintnpm run typecheck- Run TypeScript type checkingnpm run format- Format code with Prettier
GDAL Validation
npm run gdal:detect- Check if GDAL is properly installednpm run gdal:validate- Validate GDAL installation and environmentnpm 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:
totalFeaturesortotalCount: Total number of available itemshasMore: Boolean indicating if more results existlimit: Number of items returnedoffset: 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