Pelorus Nav

An open-source web-based marine chartplotter. Runs in any browser as a progressive web app — designed for phones, tablets, desktops, and e-ink devices on sailboats. Dedicated app versions for Android and iOS have even more features.

I aim for the highest quality software in all projects, including this one. All code is thoroughly tested at all levels, including back end tile pipelines and end-to-end app tests. All code is linted and type-checked, and frequently reviewed and refactored when needed to reduce technical debt.

Live web app: pelorus-nav.com Android: see github Releases page; sideload directly for now until we're in the Play Store iOS: Please contact me directly for a TestFlight invitation link

Features

• Routes and waypoints, including import/export and folders for long trips
• Track recording (works in app versions only)
• Track playback, including import/export
• Big instruments for easy visibility while sailing
• More instruments added when navigating (VMG, course to steer etc.)
• Search for anything on the charts, worldwide
• Detailed info for all chart items (buoys/lights/etc.)
• All NOAA S-57 entities decoded and shown using proper S-52 symbology
• Multi-scale quilting — seamless display across overview, coastal, and harbor chart scales
• Tides, currents and wind (wind requires network), including future predictions
• Crew Overboard tracking
• Themes: Day, Dusk, Night and E-Ink
• Download regions to work 100% offline
• Bring your own charts: import your pmtiles raster or vector charts
• Sunrise/set
• GPS: built-in device or various external options (Signal K, Bluetooth, BLE)
• Settings: layers, text & icon sizes, detail level control

Tech Stack

• TypeScript (strict) + Vite + Bun
• MapLibre GL JS for map rendering
• PMTiles for efficient vector tile serving
• Cloudflare Workers + R2 for deployment
• Biome for linting/formatting
• Vitest + Playwright for testing

Chart Data Pipeline

The S-57 pipeline converts NOAA ENC data into vector tiles. Requires gdal, tippecanoe, and uv (for the Python pipeline):

brew install gdal tippecanoe uv

# Generate vector tiles for the boston-test region (quick dev iteration)
bun run tiles

# Download ENCs then build all production regions
bun run tiles:build:fresh

# Build all production regions (ENCs already downloaded)
bun run tiles:build

See tools/s57-pipeline/ for the Python pipeline code.

Importing Your Own Charts

Chart Regions → Load from File… imports a .pmtiles file straight into the app's offline storage. Catalog charts (region charts, street basemaps, RNCs) simply become available offline — handy for installing charts on a boat tablet without re-downloading over cellular.

Bring-your-own raster charts work too: any raster PMTiles the catalog doesn't know — e.g. the satellite-imagery .mbtiles collections cruisers share (Sat2Chart, Soggy Paws, sv Ocelot) — is read on import (bounds, zoom range, name) and rendered like any other chart, quilted with the vector ENC. The conversion step is one line with the pmtiles CLI:

pmtiles convert charts.mbtiles charts.pmtiles   # brew install pmtiles

An archive is only visible within its own zoom range — a z17-only satellite export shows nothing when zoomed out (raster tiles can't be drawn below their native zoom). Below a chart's minimum zoom the app draws its footprint as a dashed magenta outline so it stays findable. To make such a chart visible at lower zooms too, add overview levels to the mbtiles before converting:

gdaladdo -r average charts.mbtiles 2 4 8 16   # brew install gdal

Packing a whole collection: cruiser chart collections are often dozens of tiny single-anchorage mbtiles per country — tedious to convert and import one at a time. tools/pack-charts.ts lists, filters, and merges them into one importable archive (later files win where tiles overlap):

# See what's in a folder (recursive), with bounds and zoom ranges
bun tools/pack-charts.ts ~/Downloads/Greece --list

# Pack everything into one archive, with overview zooms down to z12 so
# every chart is visible (as imagery or footprint) when zoomed out
bun tools/pack-charts.ts ~/Downloads/Greece --overviews 12 \
    --name "Greece Anchorages" -o greece.pmtiles

# Only the charts intersecting an area (W,S,E,N)
bun tools/pack-charts.ts ~/Downloads/Greece --bounds 24,36,27,38 -o cyclades.pmtiles

Requires the pmtiles CLI; --overviews also needs gdal (both via brew). One import then carries the whole collection, and the in-app footprint outline shows every chart patch at planning zooms.

Getting charts onto a phone or tablet: convert on a desktop, then move the .pmtiles to the device — cloud storage (Google Drive, Dropbox; iCloud on iOS), a USB cable, or a direct download all work. "Load from File…" opens the system file picker, which shows installed cloud providers directly. For multi-GB archives, download the file to the device first (browser or Files app) and import from Downloads — picking straight from a cloud provider downloads the whole file inside the picker with no progress indication. Importing copies the chart into the app's own storage, so a large chart briefly exists twice on the device.

Vector (MVT) archives are stored but not drawn — the app has no style for arbitrary vector data. Raster charts you build yourself with tools/rnc-pipeline/convert-kap.py (any georeferenced BSB/KAP) can either be imported the same way or added to RASTER_CHARTS in src/data/chart-catalog.ts — see the BVI chart entry for the pattern.

Development

Getting Started

# Install dependencies
bun install

# Start dev server
bun dev

# Run checks
bun run check        # typecheck + lint + test

Scripts

Command	Description
bun dev	Start dev server
bun run build	Production build
bun run check	Typecheck + lint + test
bun run tiles	Generate tiles (boston-test region)
bun run tiles:build	Generate tiles (all production regions)
bun run tiles:build:fresh	Download ENCs then build all regions
bun run tiles:upload	Upload tiles to R2
bun run deploy	Build and deploy to Cloudflare Workers

Architecture

See PLAN.md for the full roadmap and architecture decisions.

License

MIT; see LICENSE.md