KBOX 120 NM
For the night watch, and the long beat home

Stand your watch
with the whole sky
on board.

NEXRAD Level-2 radar, satellite cloud, lightning, wind barbs, currents, fog — rendered over NOAA ENCs in one unified chart. The briefing you'd get on shore, live at the helm.

Read the sky ← other waters
01 · NEXRAD Level 2

Read the weather before it reads you.

Full-resolution Level-2 reflectivity decoded in the browser, tinted in the NWS-RIDGE palette you already know. Not the mushy tile layer your weather app gives you — the raw feed the meteorologists use.

Worker-threaded decode means no frame drops. Sweep animation gives you storm-cell motion vectors by eye. Scroll-wheel zoom all the way into individual gates.

L2
full resolution
NIDS
velocity · echo top
NEXRAD · KBOX · L2● REFLECTIVITY
20 dBZ 30 45 55 65+
VCP 2150.5° TILT
02 · Overlays

Currents, barbs, pressure, lightning — one chart.

Stack the layers you need, strip the ones you don't. Wind barbs from model grids, lightning strikes from GLD360, currents from GoMOFS and CO-OPS stations, fog advisories from NWS, alerts painted live.

Every overlay is independently toggle-able. The chart never becomes a soup — because you decide what's on it.

11
weather layers
1-tap
toggle
OVERLAY STACK5 ACTIVE
1016101210081004 SMALL CRAFT ADV
BARBS · ISO · LTGALERT · SCA
03 · Passage Planning

Passage planning, minus the tab-switching.

Drop a route, overlay the forecast radar and the current field, run the tide clock. See departure windows that don't need a screenshot collage from four different sites.

Plans export as GPX for your chartplotter. Current set and drift are computed at each leg. Weather windows update as NEXRAD updates.

GPX
universal export
6 hr
forecast window
PASSAGE · NYC → BERMUDADay 2 · 14:00 UTC
NYC · DEPART D1 06:00 D1 22:00 D2 14:00 BERMUDA FRONT RANGE 762 NM ETA D3 18:40 UTC 5.8 KT AVG
CURRENTS · FRONTGPX ↓
The blue-water toolkit

Every overlay a sailor actually squints at.

NEXRAD L2 + NIDS

Reflectivity, velocity, echo-top, base reflectivity — in the NWS palette you already trust.

NOAA
Lightning

Live cloud-to-ground strikes via GLD360-style feed. Time-fading. Scroll context.

Live
Wind barbs

Model wind at altitude of care — gridded barbs in 5-knot increments.

GFS
Currents

Arrows with set and drift, slack indicators, auto-nearest station, GoMOFS where available.

CO-OPS
Fog advisories

NWS dense-fog zones as translucent polygons. At a glance, where to slow down.

NWS
GRIB-aware routing

Passage plans cross-reference forecast cells so your ETA accounts for what's coming.

Planning
Tide & moon

Curve, moon phase, current direction at slack/flood/ebb. The almanac, on the chart.

Almanac
Satellite cloud

GOES IR loops beneath your radar — the big picture above the local picture.

GOES
Frequently asked

Questions from the watch.

What offshore sailors ask before committing to a passage tool.

Does ChartNav replace Windy or PredictWind for marine weather?

For marine use, yes. ChartNav integrates NEXRAD Level-2 radar, wind barbs, currents, lightning, fog, and NOAA alerts over NOAA nautical charts. Windy is general-purpose; PredictWind paywalls offshore routing. ChartNav is free and marine-first.

What marine weather sources does it use?

NOAA NEXRAD L2 + NIDS radar, NWS watches/warnings/fog advisories, NDBC buoy wind and wave, NOAA CO-OPS tides and currents, GOES satellite, and a live lightning feed.

Can I plan an offshore passage with tides, currents, and weather?

Yes. Drop waypoints and ChartNav overlays forecast weather, current vectors, and tide stage per leg. Plans export as GPX 1.1. Current set and drift compute per leg for realistic ETAs.

Does it work on a phone or helm tablet?

Yes. Installs as a Progressive Web App on iOS and Android — 'Add to Home Screen' from a browser. Large-type rolling road display is available for helm use.

Is GRIB supported for passage weather?

Wind barbs and gridded fields are sourced from NWS model output today. Native GRIB file import is on the roadmap. NEXRAD, fog, and alerts are live now.

How current is NEXRAD radar?

L2 products update every 4–10 minutes per site's VCP. ChartNav renders the latest scan with no lag beyond NOAA's publish cadence.

One chart. Whole sky.

Launch it on the boat tonight. Works on phones, tablets, and chartplotter tablets.

Open ChartNav