Omahelm

The chartplotter for Omahoy.

Omahelm draws NOAA's electronic navigational charts in your Omarchy theme: soundings in feet, depth contours and shading, buoys and beacons labeled the way a paper chart labels them (G "3", Fl G 4s 4M), lights with their sectors, rocks, wrecks and isolated dangers, traffic lanes, anchorages and restricted areas. Your boat, its track and the AIS traffic come from omakeel, and every day you have sailed from omalogbook.

It reads the charts itself. The S-57 reader, the chart updates, the symbols and the renderer are all written from scratch in Rust, with no map library or GDAL in between. The reader is checked against GDAL on every California cell NOAA publishes: the same features and the same vertices, updates applied.

Status: v0.1. It plots charts and your boat. It doesn't do routes yet.

Not for navigation

Omahelm is not a primary means of navigation, and NOAA's charts in it are not certified for navigation. Carry the official charts and a backup.

Install

You need Rust (mise install in this checkout gets the right one) and the Omarchy shell.

git clone https://github.com/shieldsworks/omahelm ~/.local/share/omahelm/src
cd ~/.local/share/omahelm/src
cargo build --release --locked
bash scripts/link-plugin.sh

link-plugin.sh adds Omahelm to the Omarchy shell as the plugin org.omahoy.helm. Open it with omarchy shell shell toggle org.omahoy.helm "{}", or bind that to a key. To run it on its own instead: ./run.sh.

Charts

NOAA's charts are free. Download your waters by state:

target/release/omahelm fetch CA          # California: about 55 MB
target/release/omahelm fetch --list      # every region
target/release/omahelm fetch US5OAKFI    # or a single cell

Run fetch again to update: NOAA publishes corrections weekly. If you already have ENCs, omahelm import FILE.zip or omahelm import DIR. Charts go in ~/.local/share/omahelm/charts. Cells NOAA has canceled are skipped; omahelm index lists them.

Use

Key
h j k l, arrows	Pan
+ -, scroll	Zoom
f	Follow the boat, or stop (it opens following; panning stops it)
c	Center on the boat once
Click	What's charted here, and the wind there with the barbs on
i	What's charted at the center
w, right-click	Set a waypoint: bearing, range and ETA from the boat
W	Clear the waypoint
b	Wind barbs, from omawind: the forecast, and the wind NOAA's stations measured
s	The tidal stream, from omatide: an arrow at each of NOAA's current stations
p	Your trips: every day your logbook has a track for
d	The calendar: pick a day you sailed and go there
[ ]	The wind an hour earlier, later
t	The time bar: the forecast at the boat, hour by hour
Space	Play the wind hour by hour
n	Night Watch: red on black, to keep your night vision
?	Keys
Esc	Close a card
q	Close

The status bar shows the fix, speed and course over ground, where the pointer is and how far and which way it lies from the boat, and the scale.

With the barbs on, the wind measured at NOAA's stations shows over the forecast: the buoys offshore, and the piers and tide gauges around the Bay. Each is a barb in the theme's accent color on a dot, with its knots on the far side: 7g11 is 7 knots gusting 11. Point at one for its name and how old the report is. They're for now only, so ] to a forecast hour hides them.

Click the chart with the barbs on and the card leads with the wind there: the forecast for the hour on show, worked out for that very spot rather than the nearest barb, and, for now, the nearest station within 10 nm with how far off it is and how old its report is.

t, or the TIME chip beside the WIND label, opens a time bar along the bottom, from now to the forecast's last hour; it stays closed until you open it, and remembers. [ ] and space step the hours without it. Above its hour ticks is the forecast wind at the boat: speed shaded, gusts dashed, so you can see when the breeze builds. Drag or click to an hour, or scroll over it, and the barbs follow; the readout says the hour and the wind at the boat then, like Tue 14:00 250°T 12G16 kn. Space, or the play button, steps through the hours. Hours already fetched are kept, so going back over them is instant.

Where you've been

p draws every day omalogbook kept a track for. After a season that is one picture of your waters: every trip you have made, in the theme's accent color.

Omalogbook closes a passage whenever the fix is lost for long enough, so one afternoon can land on disk as four GPX files with holes between them. Omahelm puts the day back together: the passages in the order you sailed them, joined into the single trip they were. Where the fix was lost it draws a straight line, dashed, because that line is inferred and not where the boat went — on a flood at the Gate it is nowhere near. Solid is track. Dashed is a guess. The chip says how much of the day was which: TRIPS Mon 21 Sep 2026 20.2 nm 2.5 inferred.

d, or the TRIPS chip, opens a calendar. Days you sailed carry a dot, and the one on the chart a filled one. Move by day with the arrows or h j k l, by month with [ ], and to the next day you actually sailed with { }. Enter shows that day: the chart goes to it, the trip is drawn over the rest with a ring where the day began and a dot where it ended, and the day's run, passages and hours are named. x goes back to all of them.

The tracks are only read, never written: the vault is omalogbook's. Two commands do the same from a terminal, with no window and no engine:

omahelm trips                                  # the days, with their runs
omahelm trip --date 2026-09-21 --out day.gpx   # that day as one GPX track

omahelm trip writes the day as a single track with its holes closed, for anything else that reads GPX. The file says in its description how much of it was inferred.

Settings

~/.config/omahelm/config.toml, all optional:

units = "feet"          # feet, meters or fathoms
safety_depth = 10       # soundings this shallow or less are drawn bold
shallow_contour = 6
safety_contour = 12     # water shallower than this is shaded as unsafe
deep_contour = 30
palette = "theme"       # theme, or paper for the colors of a paper chart
logbook = "~/Logbook"   # the tracks the trips layer draws

Depths are in units. Omahelm uses the shallowest contour the chart has at or below your safety contour, the way S-52 does.

logbook is only needed if your vault isn't where omalogbook's own config says it is. Omahelm reads <logbook>/tracks/*.gpx, or the folder itself if it holds the GPX files.

The colors follow the Omarchy theme and change with it. Colors that mean something at sea don't: a green buoy stays green even if your theme's "green" is amber.

Night Watch (n, or the NIGHT button) turns this window red on black, chart and all, whatever the theme. With every color a red, marks are told apart by brightness, shape and label: red buoys are bright, green ones dark, yellow and white ones pale, and green cans stay square and red nuns pointed. It's off each time Omahelm starts, and it changes only this window, so Omalookout beside it can stay as it is.

How it works

omahelm serve is the chart engine. It indexes the charts, draws 256-pixel tiles on demand into ~/.cache/omahelm/tiles, and answers what's charted at a point. The window is a thin Quickshell client that places the tiles and draws the boat and AIS traffic on top. They talk over a Unix socket, described in docs/protocol.md.

The window starts the engine when it isn't running. omahelm render draws a view to a PNG without either.

Data

Charts: NOAA Office of Coast Survey electronic navigational charts, public domain. The S-57 object catalogue tables are generated from GDAL's copies (MIT).

License

MIT