Getting Started

Opening the app

Pelorus Nav runs at pelorus-nav.com/app in any modern browser. For use on the water, install it:

• Phone/tablet browser — use your browser's "Add to Home Screen" / "Install app" option. The installed app runs full-screen and works offline.
• Android (beta) — install through the Play Store's closed testing (the maintainer adds testers; sign up), or download the signed APK from the latest GitHub release.
• iOS (beta) — available through TestFlight (sign up to join).

The web app updates itself: when a new build is published it loads in the background and the app reloads at a quiet moment (or tap Reload now). The Play Store and TestFlight apps update through the store. An APK installed from GitHub instead checks for a newer release each time it starts and shows a notice that opens the release page. Untick Check for updates at startup in the About dialog (menu → About) to stop the web app's or the APK's check.

On first launch the app shows a navigation warning and user agreement, and asks for location permission the first time GPS is used. By default the chart opens on the built-in NOAA vector charts, streaming tiles as you pan — no setup needed while you're online.

The main screen

• Top bar — tools and panels: track recording (REC), instruments (INST), tracks (TRK), routes (RTE), and more under the ☰ menu on small screens. The gear (SET) opens Settings.
• Instruments (left) — big SOG/COG readouts, sized to be glanceable from the helm. The green dot shows GPS health; it turns into a NO GPS badge when the fix goes stale. Toggle the instrument panel with INST.
• Vessel — the blue arrow, with your course line projected ahead.
• COB button — crew-overboard: press and hold to drop a COB mark and start navigation back to it.
• Recenter button (next to COB) — locks the chart back onto the vessel and cycles the chart mode (see The Chart Display).
• Bottom badges — current depth/bearing units and chart source.

Settings worth changing

Open Settings (gear, top right). Most defaults are fine; these are the ones people change first, all on the Appearance tab:

• Bearings — magnetic (default) or true. Affects every bearing the app shows, labeled °M or °T accordingly.
• Speed / depth units — knots, MPH, or km/h; feet (default), meters, or fathoms. Depth soundings on the chart follow this immediately. Official charts store depths in meters; converted depths are rounded down, as on NOAA's own charts, so they can read one foot shallower than an older paper chart. Heights and clearances show in feet when depths are in feet or fathoms, also rounded down (clearances to a tenth of a foot).
• Display theme — Day, Dusk, Night, or E-ink. Night mode dims the whole chart to preserve night vision.
• Detail — how much chart detail is drawn; see detail levels.
• Chart text / icon size — scale up chart labels and symbols for readability at a distance.
• Waypoint size — scale waypoint and route markers up or down, including the handles shown while editing a route. Waypoint names keep the standard text size.
• Depth shading — the Shallow / Safety / Deep thresholds control the blue depth tinting. Set them for your boat; the defaults are NOAA's 5 / 11 / 17 ft. The bold safety contour is the shallowest contour whose label is at least your Safety setting, and soundings at or shallower than it are drawn darker. Since NOAA's US contours read 5, 11, 17 and 29 ft (see Speed / depth units above), pick one of those to land on a contour. White deep water draws deep water white instead of pale blue in the Day theme, for a paper-chart look or a brighter screen in sunlight.
• Keep screen on — "When GPS active" keeps the display awake while you're underway.
• Screen lock & volume-key zoom (Android) — the volume keys zoom the chart, and Lock screen in the menu disables the touchscreen so spray and stray taps can't change anything under way; one volume press unlocks (so does holding a finger still on the screen for three seconds). Choosing Lock screen with this setting off offers to turn it on.
• Close dialogs & recenter when idle — after a minute of inactivity, open panels close and the chart snaps back to your vessel. That's what you want underway (the chart is always where your boat is when you glance at it), but it can be confusing while you're exploring the app at home — panels seem to close themselves. Feel free to turn it off while learning or planning, and back on aboard.

Try it from your couch

Settings → Navigation → GPS source includes a Simulator that sails a boat around Boston Harbor. It's the easiest way to explore navigation features — routes, instruments, tracks — before you're on the water.

Downloading charts for offline use

Streaming charts need an internet connection. Before heading out, download your region so charts live on the device: open Chart Regions (RGNS, under ☰ on small screens).

Each region covers a stretch of coast (Northern New England, Southern New England, New York & NJ, …) and shows its approximate download size. Tap the download button to store it; downloaded regions show a ✓ with their size and date. Downloads queue: tap several and they arrive one after another, each row showing its progress, with a Cancel All row at the top that also shows how much is left. If the connection drops or stalls, the download shows Waiting for network… and continues from where it stopped once the app is back on screen with a connection; after several failed tries it shows the error, and tapping download again still resumes. On Android, downloads (and their retries) keep going while you use other apps or the screen is off, with a Downloading charts notification showing their progress; on iOS they pause in the background and continue when you return to the app. The radio button selects your active region — the one used for place-name search.

Most regions also offer an optional street basemap — an offline copy of the land map that otherwise streams from OpenStreetMap. Download it too if you want street-level land detail offshore; without it you still get the chart's own land areas.

When a chart update is published, downloaded regions show an Update available button — updating re-downloads only that region. With several regions or basemaps out of date, an Update All row at the top of the panel queues them all. The panel footer shows total storage used. Downloaded charts can be removed individually or all at once.

Charts you bring yourself, such as satellite-imagery collections for waters with poor official charts, load from the same panel: see Your Own Charts.

Save your home port

Worth doing on day one: make your slip or mooring a waypoint.

1. Right-click / long-press your spot on the chart and choose Mark waypoint here.
2. Open Waypoints (WPT) and tap the pencil on the new waypoint.
3. Name it, pick the Anchorage icon (an anchor symbol on the chart), and add a note if you like — mooring number, harbormaster phone, whatever. Save.

The icon sets the chart symbol — Anchorage, Hazard, Fuel, and POI are the other options. From now on, Navigate to on that waypoint gives you a live bearing and distance home from wherever you are — see Following a route for what the navigation instruments show.

Each waypoint row also has an eye to take it off the chart without deleting it, and waypoints can be put in folders and selected in bulk the same way routes can — worth knowing before you import a few hundred marks from another chartplotter.

Next steps

• The Chart Display — chart modes, layers, and detail levels.
• Routes — plan a route, then follow it.