ChartNav
For dive boats & scuba charter operators

Slack water. Anchor set. Dive it.

NOAA slack-tide windows, live current vectors at the site, an anchor alarm that keeps watch while divers are down, and the weather before it reads you. The map behind this text is live.

6 mintide resolution
Livecurrent vectors
Driftanchor alarm
vessels live now
The window

Call slack before the briefing, not after the splash

The dive belongs to the tide. ChartNav draws today's real curve, the current field around the site, and the charted bottom — on one screen.

The tide window — today's real curve

NOAA CO-OPS predictions drawn as they stand right now; the amber line is this moment. In the app the nearest station auto-locks to your GPS, so the slack you brief is the slack at your site.

reading the tide…
LIVE · NOAA CO-OPS 6-minute predictions · slack windows called in the app

Current over the site

RTOFS 1/12° surface currents as a live vector field — set and drift for the descent line, the drift plan, and the pickup.

loading current field…
LIVE · RTOFS 6-hourly cycles · CO-OPS station vectors too

The bottom, as charted

Real NOAA ENC — wrecks with least depths, rocks, obstructions, depth tints you can re-threshold to your gas plan. Soundings in feet, meters, or fathoms.

loading ENC…
LIVE · NOAA ENC vector tiles · wrecks by least depth
On station

Divers down. Boat held. Sky watched.

While the group is on the wreck, the boat keeps its own watch — on the hook, on the crew ashore, and on the cell building to the southwest.

Anchor watch, animated

Set a drift radius and the alarm watches the GPS trace against it. This is the actual logic, running in this card — watch the boat swing at anchor, then drag, then get caught.

setting the hook…
LIVE LOGIC · runs with the screen off in the app · pair a horn via audio out

The buoy, before you steam

Live NDBC observations from the buoy nearest the site — wind, gust, waves, water temperature. These numbers are the buoy's latest report, not a forecast.

calling the buoy…
LIVE · NDBC latest obs · wave height is the go / no-go

The buddy line, fail-safe

Live position sharing between boats and shore crew, with a freshness gate: when a feed goes quiet, it says CONTACT LOST — it never quietly shows a stale dot. Watch the demo run the failure.

starting buddy demo…
LIVE LOGIC · freshness-gated · contact-lost alerts fail safe

Lightning, before you hear it

Blitzortung strikes on a 60-minute rolling window with radius alerts — the surface interval decision, made early.

loading strikes…
LIVE · alerts at your radius, 5–100 nm

NEXRAD radar on the chart

Real WSR-88D scans, looping the last eight sweeps. When the afternoon build-up starts inland, you see it over the same chart your sites are marked on — with NWS warning polygons when they're issued.

loading radar loop…
LIVE · Level-2 + NIDS in the app · dense-fog advisories too
The dive-day kit

Anchor alarm

Drift radius over your GPS trace. If the hook drags with divers down, it yells.

Man overboard

Long-press the chart: MOB, anchor, or mark — position fixed at the press.

Dive-site library

Waypoints at wrecks, reefs, and holes with notes — GPX 1.1 export to the plotter.

NDBC buoys

Live wind, gust, and wave from the buoy nearest the site — the sea state before you steam.

Fog advisories

NWS dense-fog advisories and the GOES fog layer — before the bank rolls in.

Traffic overhead

Live AIS of everything near the anchorage — see who's bearing down on the flag.

One backend, four helms

Web in any browser · iPhone & iPad native app · Apple TV boat-dashboard mode · Apple Watch on your wrist. Sites, routes, and alarms stay in sync.

PWA today · native apps in TestFlight
CAUTION ChartNav is a planning and situational-awareness tool, not a navigation system or a dive computer. Currents are model output and can be wrong; verify conditions at the site. Carry official charts and publications, and keep a proper watch.

Questions from the dive deck

How does ChartNav call slack tide?

NOAA CO-OPS current predictions at the station nearest your site, drawn as a live curve with the weak-water windows readable at a glance. The station auto-locks to your GPS.

Does the anchor alarm really work with the screen off?

Yes — in the browser or the installed PWA it keeps watching your GPS trace against the drift radius. Pair the phone's audio out with a horn if you want it loud.

Can I mark and save dive sites privately?

Yes. Drop waypoints with notes. Libraries live on your device in browser storage and never leave unless you export as GPX.

What weather sources does ChartNav use for dive planning?

NOAA NEXRAD Level-2 and NIDS, NWS alerts and dense-fog advisories, NDBC buoy wind and wave, GOES satellite, and live lightning feed.

Can I see other boats approaching my dive site?

Yes. Every AIS-equipped vessel within range renders on the chart with live position, speed, and heading — useful for managing the dive flag radius and pickup zone.

Call the window. Drop in.

Browser-based. No App Store. Your phone or helm tablet, a chart, and the whole dive-day briefing.

Open ChartNav