================================================================================ SCHWOJ ALARM — USER MANUAL & PRACTICAL GUIDE (ENGLISH) ================================================================================ Copyright (C) 2026 Hauke Christoph, Wellenweg GbR — All rights reserved Project: Schwoj Alarm (Smart PWA Anchor Watch & Shore Remote Monitor) Website: https://www.schwojalarm.com Repository: SchwojAlarm / Wellenweg GbR Version: v61026 Release: October 2026 ================================================================================ TABLE OF CONTENTS -------------------------------------------------------------------------------- 1. OVERVIEW & PHILOSOPHY 2. SYSTEM REQUIREMENTS & PWA INSTALLATION 3. BOAT MODE: ONBOARD ANCHOR WATCH 3.1 Preparation & Radius Calculation 3.2 PIN Generation & Sharing 3.3 Starting Watch & GPS Warmup Phase 3.4 Live Monitoring & Polar Radar Plot ("Yarn Ball" Pattern) 3.5 Alert Levels & Visual Signaling (Green / Yellow / Red) 3.6 Night Vision Mode (OLED Deep Red) 3.7 Ending the Watch 4. SHORE MODE: REMOTE MONITORING ON LAND 4.1 Connecting via PIN or Share Link 4.2 Dashboard & Status Feedback 4.3 Audio Siren & Shore Sound Test 4.4 Continuous Operation ("Keep Display ON") & Bedside Night Vision 4.5 Connection Watchdog (90-second Signal Loss Safeguard) 5. PRIVACY & SECURITY ARCHITECTURE 6. SEAMANSHIP & PRACTICAL SKIPPER TIPS 7. TROUBLESHOOTING & FAQ ================================================================================ 1. OVERVIEW & PHILOSOPHY ================================================================================ Schwoj Alarm is a minimalist, privacy-respecting anchor watch web application crafted by sailors for sailors. It serves as an electronic assistance tool for two cruising scenarios: 1. Onboard Anchor Watch: Monitors the swinging motion (German: "Schwojen") of your yacht at anchor, detects dragging and visualizes the natural motion pattern ("yarn ball"). The local watch runs 100% OFFLINE directly in your browser using only the device's internal GPS sensor. 2. Shore Leave (Remote Monitor): Allows the skipper and crew to monitor the boat's relative position, distance, and bearing from shore via a temporary 6-character session PIN with an automated connection watchdog (triggering if the boat signal is lost for over 90 seconds). ================================================================================ 2. SYSTEM REQUIREMENTS & PWA INSTALLATION ================================================================================ Schwoj Alarm is built as a Progressive Web App (PWA). It runs directly inside any modern web browser without requiring app store downloads or logins. Requirements: - Any smartphone, tablet or laptop running a modern browser (Safari, Chrome, Firefox, Edge). - Internal GPS receiver on the boat device. - For Shore Monitoring: Active mobile data or Wi-Fi on both devices. Home Screen Installation (Recommended): - Apple iOS (Safari): 1. Open the app in Safari. 2. Tap the "Share" button (box with upward arrow). 3. Scroll down and choose "Add to Home Screen". - Android (Chrome): 1. Open the app in Chrome. 2. Tap the three-dot menu icon or the in-app installation prompt. 3. Select "Install app" or "Add to Home screen". Advantages of Home Screen Installation: - True full-screen mode without browser address bars. - Enhanced background reliability and resilient Screen Wake Lock support. - One-tap quick launch just like a native app. ================================================================================ 3. BOAT MODE: ONBOARD ANCHOR WATCH ================================================================================ 3.1 Preparation & Radius Setting: The "Yarn Ball" Principle ------------------------------------------------------------- Schwoj Alarm differs from traditional chartplotter anchor alarms: We do not monitor the huge 360° circle around the anchor drop point on the seabed. Instead, we monitor the tightly bounded swinging motion of your settled vessel— the so-called "yarn ball" pattern (or: "Spaghetti plot"). Why is this an operational advantage? In traditional anchor alarms with a 50–60 m radius, the system will not trigger during a 180° wind shift until the vessel has traveled all the way across the circle. With Schwoj Alarm, leaving this cluster or dragging triggers an alert after two consecutive confirmed position fixes outside your chosen radius. Step-by-step procedure: 1. Complete your anchoring maneuver normally. Let the anchor dig in, pay out your scope, attach the snubber and allow the vessel to settle into the wind or current. (No frantic phone tapping required during maneuvering!) 2. Start the watch comfortably from the cockpit: The app captures the boat's current settled position as the reference center. 3. Choosing the Swing Radius: - The radius must be determined by the skipper based on water depth, deployed chain length, vessel displacement and prevailing wind/current conditions. - As a general practical guideline in settled conditions, 15 to 25 meters is often chosen (default preset: 20 m). - Golden Rule: Never set a radius larger than your total deployed chain length! 3.2 Setting & Sharing Your PIN -------------------------------- When heading ashore: - The 6-character alphanumeric PIN serves as your session key for remote tracking. - Enter any 6-character PIN (or let the system complete your input) into the "Monitor PIN" field. It is automatically remembered in your browser. - Tap "🔗 Share PIN" to send a direct monitoring link via WhatsApp, Signal, SMS or email to your shore devices. - Note: If the boat phone is offline (no cellular data/Wi-Fi), the Share button is automatically hidden since remote data relay is unavailable. 3.3 Starting Watch & GPS Warmup Phase ------------------------------------- 1. Accept the maritime disclaimer on first launch (good seamanship agreement). 2. Tap "Start Alarm". 3. The automatic GPS warmup and calibration sequence begins: - Satellite acquisition & stabilization: Once a fix is available and the required threshold is reached, an unconditional 5-second settling countdown runs ("Stabilizing: Xs (≤5m)"). - 0–30 seconds: Enforces a strict accuracy of ≤ 5 m. - After 30 seconds: Threshold dynamically adjusts to ≤ max(10 m, 30% of chosen radius) to accommodate challenging geometry. - Once the signal remains continuously stable within the threshold for the full 5 seconds, the watch arms automatically. The boat's current settled position is locked as the reference point. - Screen Wake Lock activates simultaneously to keep your display awake. 3.4 Live Monitoring & Polar Radar Plot ("Yarn Ball" Pattern) ----------------------------------------------------------- While the watch is running: - Display: - Distance to reference point and compass bearing (e.g. "14m NW"). - Status banner: "Watch Active" or "Local watch active" (with subtle hint "📡 Offline mode" below if no cellular network is available). - Polar Radar View: - Crosshair Center: Set reference point. - Outer Circle: Configured swing radius boundary (e.g. "Radius: 30m"). - Green Dot: Live vessel position. - Gray Breadcrumb Trail: Historical positions over recent hours. Under steady breeze, your yacht will draw the characteristic "yarn ball" swinging pattern. If the wind shifts or the anchor drags, the dot visibly breaks out of the ball. 3.5 Alert Levels & Visual Signaling ----------------------------------- Schwoj Alarm operates with three distinct security stages: 1. GREEN (Safe / OK): - Vessel is within 80% of the defined radius. - Deep black background, no acoustic sirens. 2. YELLOW (Warning / Boundary or Weak GPS): - Case A: Vessel is between 80% and 100% of the radius. - Case B: Temporary GPS glitch (accuracy worse than allowed limit). - Display shows a yellow warning border; no continuous siren. 3. RED (ALARM — Dragging or Signal Loss): - Cause 1 (Anchor Drag): Vessel exceeds the boundary on 2 consecutive GPS fixes (prevents false alarms from single-point GPS jumps). - Cause 2 (GPS Failure): No GPS update received for more than 30 seconds. - Alerting: Fullscreen flashing red background accompanied by a loud, penetrating maritime ship siren (when audio is unmuted). 3.6 Night Vision Mode (OLED Deep Red) ------------------------------------- - Tap "🌙 Night Vision" to activate night mode. - Key benefits: - Pure OLED black background with all readouts, radar and buttons rendered in dim, eye-friendly red. - Hides bright operating system status bars (battery, clock) using Fullscreen API. - Preserves biological night vision adaptation on watch or in the bunk. - Dismissing: A simple tap anywhere on the screen immediately exits night mode. 3.7 Ending the Watch -------------------- - Tap the red "Stop Alarm" button. - Geolocation tracking stops, the wake lock is released and a "BEENDET" (ended) signal is transmitted to the shore monitor. ================================================================================ 4. SHORE MODE: REMOTE MONITORING ON LAND (MONITOR) ================================================================================ 4.1 Connecting via PIN or Share Link ------------------------------------ 1. Switch to the "Shore (Monitor)" tab on your phone, swipe left from the start screen or open `monitor.html` directly. 2. If you opened a shared link from your boat, the PIN is pre-filled and connects automatically. 3. Otherwise: Enter the 6-character PIN from the boat device and tap "Connect". 4.2 Dashboard & Status Feedback ------------------------------- The shore dashboard mirrors the boat's status in real time: - Distance & Compass Heading: e.g. "16m NW". - Signal Status: - "Signal active" (last heartbeat received < 10 seconds ago). - "Signal Xs ago" (last heartbeat received X seconds ago). - Live Radar Plot: Displays your boat's swinging pattern just like on board. - Polling: The monitor updates automatically every 10 seconds. 4.3 Audio Siren & Shore Sound Test ---------------------------------- - Audio is MUTED by default in Shore mode ("Sound is OFF") so your phone won't blare unexpectedly in a restaurant or shop. - Tap "Sound is OFF" to arm the siren ("🔊 Sound is ON"). - Tap "🔊 Test Sound (3s)" to test volume and ensure the browser has granted unrestricted audio playback permissions. 4.4 Continuous Operation ("Keep Display ON") & Bedside Night Vision ------------------------------------------------------------------- When leaving the phone on a nightstand in a hotel or holiday apartment: 1. Tap "💡 Keep Display ON": - When OS lock is granted: Button turns blue ("Display stays ON") with a yellow bulb icon. Your screen will not go dark. - When OS restricts wake lock (e.g. low-power battery saver): Button remains dark gray ("Display ON (lock restricted)"). 2. Progressive Disclosure (Unlocking Night Vision): - Activating "Display ON" unlocks the "🌙 Night Vision" button right below it. - Tap it to switch into deep-red bedside night mode. - Tap anywhere on screen to exit night mode. - Turning off "Display ON" cleanly dismisses Night Vision and hides the button. 4.5 Connection Watchdog (90-second Signal Loss Safeguard) -------------------------------------------------------- Safety is top priority: If no heartbeat is received from the boat for over 90 seconds (due to cell coverage dropouts, dead boat battery or browser crash): - Dashboard alerts: "⚠️ CONNECTION LOST". - If audio is armed, the shore monitor sounds an alarm once the 90-second timeout is exceeded. This ensures you are reliably alerted if communication with the boat is lost. ================================================================================ 5. PRIVACY & SECURITY ARCHITECTURE ================================================================================ Schwoj Alarm adheres to a data-minimal privacy architecture: - No Coordinates on Servers: Your absolute GPS coordinates (latitude / longitude) NEVER leave your boat! Locations, tracks and anchor spots are NEVER transmitted or stored on servers. - Strictly Local Math: Distance to anchor, compass bearing and swinging patterns are computed exclusively in the local browser runtime on your boat. - Ephemeral Data Relay: The boat heartbeat only sends relative telemetry ("12m", "NW", "OK"). Data on the server is keyed temporarily to your 6-character session PIN and deleted upon ending the watch or automatically after 48 hours of inactivity. - Zero Accounts & Zero Tracking: No registration, no email address, no passwords, no analytics, no advertising. ================================================================================ 6. SEAMANSHIP & PRACTICAL SKIPPER TIPS ================================================================================ 1. Continuous Power Supply: Continuous GPS polling and screen wake lock consume power. Keep the boat phone plugged into a 12V charger or a trusted power bank. 2. Device Placement on Board: Position the boat phone where it has an unobstructed view of the sky (e.g. companionway, under the sprayhood or deck saloon window). Avoid deep storage lockers or inside steel/aluminum hulls that block satellite reception. 3. Dedicated Backup Smartphone: An older, retired smartphone makes an ideal dedicated anchor watch. Leave it aboard connected to power with a cellular SIM card or onboard Wi-Fi hotspot while carrying your primary phone ashore. 4. Realistic Radius Selection (Yarn Ball vs. 180° Wind Shift): Set the radius deliberately compact, yet mindful of normal GPS jitter: 15 to 25 m is usually ideal (maximum the deployed chain length). Excessive radius (e.g. 50 m): A dangerous 180° wind reversal or creeping dragging will be slept through. Too narrow radius (< 10 m): Natural yawing in gusts or GPS noise triggers annoying false alarms. 5. Legal & Seamanship Disclaimer: Schwoj Alarm is an electronic aid designed to support watchkeeping. It never replaces good seamanship, proper lookout, continuous anchor watches or mandatory navigation equipment. Use at your own risk. Liability for damages arising from injury to life, body or health and for intentional or grossly negligent breaches of duty remains unaffected. In all other cases, liability for slight negligence is excluded. ================================================================================ 7. TROUBLESHOOTING & FAQ ================================================================================ Q: "Can I lock my phone with the power/standby button during anchor watch?" A: No, under no circumstances! Locking the phone freezes background JavaScript timers and GPS location tracking in mobile browsers (most notably iOS Safari). Keep the device connected to a charger, keep the screen unlocked and activate the built-in "Night Vision" mode instead for a pitch-black, energy-saving OLED display. Q: "Starting GPS... / Timeout: Could not reach required GPS accuracy." A: The phone cannot acquire sufficient GPS satellites. Move the device on deck with an open sky view. Turn off Airplane Mode and verify in device settings that browser location permissions are set to "Precise Location". Q: "Display turns off after 1 minute despite Keep Display ON." A: Certain operating systems (notably iPhones in Low Power Mode with yellow battery icon) restrict the Screen Wake Lock API. Disable Low Power Mode in iOS battery settings. Q: "Shore Monitor keeps showing CONNECTION LOST." A: Check the boat phone's internet connection. In remote coves, mobile network reception can drop out. The 90-second watchdog sounds to keep you safe whenever signals disappear. Q: "No sound when the alarm triggers." A: Modern web browsers block unprompted audio until user interaction occurs. Always tap "🔊 Test Sound (3s)" once to unlock the audio engine. Check the hardware mute switch on the side of your phone as well. Q: "PIN occupied! The PIN is currently in use by another boat." A: While rare, another vessel may be using the same 6-character PIN. Simply modify your PIN in the input field (e.g. change a letter or number). ================================================================================ Fair winds, quiet anchorages and safe holding! Made in Germany — Hauke Christoph, Wellenweg GbR USt-IdNr.: DE288696915 | Contact: info [at] schwojalarm.com | www.wellenweg.de ================================================================================