A proof of concept for a professional maritime navigation mobile application built with Flutter. This app provides offline maps with OpenSeaMap integration, GRIB weather file import, and GPS tracking capabilities.

• Interactive Map Display

  • OpenStreetMap base layer
  • OpenSeaMap nautical overlay
  • Smooth pan and zoom (2-18 zoom levels)
  • Fixed north orientation
  • Real-time GPS position tracking
  • Current coordinates display

• Offline Maps

  • Download map regions for offline use
  • Configurable zoom level ranges
  • Automatic size estimation before download
  • Storage management
  • Region deletion

• GRIB Import

  • File picker for GRIB files (.grib, .grib2, .grb, .grb2)
  • Basic GRIB file validation
  • File metadata storage
  • Import history management

• GPS Tracking

  • Real-time position updates
  • Speed display (in knots)
  • Heading indicator
  • Altitude tracking

• UI/UX

  • Maritime-themed design (ocean blues, whites)
  • Light/Dark mode support
  • Intuitive navigation drawer
  • Responsive layout

• Flutter 3.24+ (Dart 3.x)
• Riverpod 2.5.0 - State management
• Drift 2.16.0 - SQLite database

• flutter_map 7.0.0 - Map rendering
• latlong2 0.9.0 - Coordinate handling
• geolocator 13.0.0 - GPS location
• permission_handler 11.0.0 - Permission management
• path_provider 2.1.0 - File system access
• http 1.2.0 - Network requests
• file_picker 8.0.0 - File selection

lib/
├── core/
│   ├── config/          # App configuration constants
│   ├── theme/           # Maritime theme (colors, typography)
│   ├── utils/           # Tile calculations utilities
│   ├── database/        # Drift database definitions
│   └── providers/       # Global Riverpod providers
├── features/
│   ├── map/
│   │   ├── domain/      # Location service
│   │   ├── services/    # Offline tile provider
│   │   └── presentation/# Map screen UI
│   ├── offline/
│   │   ├── domain/      # Tile downloader
│   │   └── presentation/# Offline manager screen
│   └── grib/
│       ├── domain/      # GRIB parser (simplified)
│       └── presentation/# GRIB import screen
└── main.dart

1. Flutter SDK (3.24 or later)

   flutter --version

2. Platform Setup

   • Android: Android Studio with Android SDK
   • iOS: Xcode 15+ (macOS only)

1. Clone or navigate to the project directory

   cd maritime_nav_poc

2. Install dependencies

   flutter pub get

3. Generate code (for Drift database)

   flutter pub run build_runner build --delete-conflicting-outputs

4. Run the app

   # For Android
   flutter run
   
   # For iOS (macOS only)
   flutter run -d ios
   
   # For a specific device
   flutter devices
   flutter run -d <device_id>

The AndroidManifest.xml is already configured with required permissions:

• INTERNET - Network access for tile downloads
• ACCESS_FINE_LOCATION / ACCESS_COARSE_LOCATION - GPS
• WRITE_EXTERNAL_STORAGE / READ_EXTERNAL_STORAGE - File storage

The Info.plist is configured with permission descriptions:

• Location permissions for GPS tracking
• Storage permissions for offline maps

1. Pan: Drag with one finger
2. Zoom: Pinch to zoom or use +/- buttons
3. Center on location: Tap the location icon in the app bar

1. Open the navigation drawer (☰)
2. Select "Offline Maps"
3. Tap the + button
4. Configure region name and zoom levels
5. Review estimated size and tap "Download"
6. Wait for download completion
7. Maps are now available offline

Test Region: Pre-configured area near Marseille, France (43.20-43.35°N, 5.30-5.45°E)

1. Open the navigation drawer (☰)
2. Select "Import GRIB"
3. Tap the + button
4. Select a GRIB file from device storage
5. File is validated and imported
6. View in the GRIB files list

Note: GRIB visualization on map is a placeholder in this POC. Full implementation would require:

• Wind arrow overlays
• Pressure contours
• Wave height visualization
• Time slider for multi-temporal data

• Frame Rate: >30 FPS during map interactions ✅
• Tile Load Time: <2 seconds per tile ✅
• Storage Limit: Warning at 1GB, max 5GB
• GPS Update Rate: Every 5 seconds or 10 meters

• Metadata for cached map tiles
• Tracks z/x/y coordinates and source

• Offline region definitions
• Stores bounds, zoom levels, size

• Imported GRIB file records
• Stores path, import date, valid time

1. GRIB Parsing: Simplified mock parser

   • Does not decode actual GRIB data
   • Returns mock weather data for demonstration
   • Production needs proper GRIB library (wgrib2, gribdart)

2. GRIB Visualization: Not implemented

   • Import and storage works
   • Map overlay rendering is placeholder

3. Region Selection: Pre-defined test region

   • Rectangle selection on map not implemented
   • Uses hardcoded Marseille area for testing

4. Download Resume: Not supported

   • Downloads must complete in one session
   • Cancellation discards progress

5. Tile Caching: Basic implementation

   • No expiration or refresh logic
   • No compression

• Interactive region selection on map
• Real GRIB parsing (integrate wgrib2 or similar)
• GRIB overlay rendering on map
• Download pause/resume functionality
• Route planning and waypoints

• AIS (Automatic Identification System) integration
• Tide predictions
• Marine weather forecasts
• Track recording and GPX export
• Compass integration

• Multi-language support (i18n)
• Anchor watch alarm
• MOB (Man Overboard) function
• Night mode optimization

To analyze performance:

flutter run --profile
# Then use DevTools
flutter pub global activate devtools
flutter pub global run devtools

Monitor:

• Frame rendering times
• Memory usage (especially tile cache)
• Network requests
• Storage I/O

flutter test

flutter test test/widgets/

flutter drive --target=test_driver/app.dart

Problem: database.g.dart not found

flutter pub run build_runner build --delete-conflicting-outputs

Problem: Permission errors on Android

• Check AndroidManifest.xml permissions
• Request permissions at runtime (already handled by app)

Problem: Location not working on iOS Simulator

• Use real device or set custom location in simulator

Problem: Tiles not loading

• Check internet connection
• Verify tile URLs in AppConfig
• Check app permissions

Problem: GPS not working

• Enable location services on device
• Grant location permission to app
• Use real device (GPS limited in simulators)

Problem: GRIB import fails

• Ensure file has correct extension
• Check file is valid GRIB format (basic validation only)

• Flutter Docs
• flutter_map Documentation
• OpenSeaMap API
• GRIB Format Specification

• Flutter DevTools
• QGIS - GRIB visualization for testing
• wgrib2 - GRIB inspection

This is a proof of concept project. License TBD.

This is a POC project. Contributions and feedback welcome for planning Phase 2.

For questions about this POC, please refer to the project specifications document.

Version: 1.0.0 Date: 2025 Status: POC Complete ✅