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Features Research

Domain: Maritime Ship's Logbook PWA Researched: 2026-05-26 Confidence: HIGH

Feature Categories

1. Vessel & Crew Master Data (Stammdaten)

  • Vessel Profile: Capture Yachtname, Heimathafen, Charterfirma, Eigner, Kennzeichen/Zulassungsnummer, Funk-Rufzeichen, ATIS-Nr, MMSI-Nr.
  • Crew Registry: Skipper and crew profiles (up to 6 members) with Name, Anschrift, Geburtstag, Tel-Nr, Nationalität, Pass-Nr, Blutgruppe, Allergien, Krankheiten.
  • Deviation Table (Steuertafel): Standard magnetic compass deviation table mapping Compass Heading (MgK) from 000° to 360° (in 10° increments) to Deviation (Ablenkung).

2. Journey Logbook (Logbucheintrag)

  • General Journey Info: Date, Day of Travel (. Reisetag), Departure (Reise von) & Destination (nach).
  • Hourly/Event Entry: Time, Compass Course (MgK), Chart Course (rwK/KüG), Wind (pressure hPa, direction, strength), Sea State (Seegang), Weather (icons/symbols), Current (Strom), Heel (Lage), Sail Configuration (G, F, S, StF) or Motor run hours, Log reading, Distance, and GPS Coordinate with custom remarks.
  • Daily Summaries: Position morning & evening, freshwater/fuel stock checks (morning stock, refilled, evening stock, daily consumption).
  • Sign-off: Signatures of Skipper and Crew (names in block letters + signature).

3. Smart Integrations (Assistance)

  • OpenWeatherMap Integration: Automatically query and pre-fill wind direction/strength, pressure, and weather state based on geographical coordinates.
  • GPS Coordinates Capture: Fetch current latitude/longitude via device GPS and pre-fill coordinates into log entries.

4. Data Management & Privacy

  • Local Database (IndexedDB): Direct database queries and local storage in browser sandbox.
  • CSV Data Export: Generate and download formatted CSV logbooks directly, or trigger local email/message sharing.
  • Offline Assets & Service Worker: Cache all HTML, JS, CSS, and assets so the application runs completely disconnected.

Feature Scoping: Table Stakes vs Differentiators

Feature Category Type Complexity Notes
Vessel Profile Stammdaten Table Stake Low Form entry with validation.
Crew Registry Stammdaten Table Stake Low Up to 6 profiles, standard fields.
Logbook Form Logbuch Table Stake Medium Complex form containing wind, course, and sails.
Deviation Table Stammdaten Table Stake Low Grid mapping MgK to Abl.
CSV Export Data Table Stake Medium Client-side CSV generation and download trigger.
Local Storage Data Table Stake Medium IndexedDB schema setup and migration.
Offline PWA System Table Stake Medium Service Worker configuration.
GPS Fetching Assistance Differentiator Low HTML5 Geolocation API integration.
OpenWeather API Assistance Differentiator Medium Needs API key, coordinates, and fallback for offline.
Adaptive OS UI UI/UX Differentiator High Modifying UI based on UserAgent/OS detection.

Anti-Features (Do Not Build)

  • Cloud DB Sync: Violates local-only privacy constraint.
  • Central User Login / Registration: No remote accounts; the app is immediately active upon loading.
  • Remote Sharing Server: Logbook files must be exported directly from the device (CSV download or local email handler).

Dependencies & Risk Analysis

  1. Weather API Dependency: OpenWeatherMap API requires internet access. If the user is offline (common at sea), the API will fail.
    • Risk Mitigation: Implement clean offline fallback. Inform the user they are offline and allow manual weather entry.
  2. GPS Geolocation Dependency: Requires browser permissions. Device GPS can be slow to lock or unavailable on some tablets without GPS chips.
    • Risk Mitigation: Allow manual entry of latitude and longitude as fallback.
  3. PWA Storage Cleared by OS: iOS Safari sometimes purges IndexedDB for apps not added to the home screen if they are unused for 7+ days.
    • Risk Mitigation: Display a warning prompting the user to install the app to the home screen (PWA installation protects storage) and encourage regular backups using the CSV export.

Features research for: Kapteins Daagbox PWA Researched: 2026-05-26