A Working Model project
Slackwater is a tides-and-weather dashboard for the U.S. coast. Pick any of the 3,600+ NOAA stations nationwide and see the live tide curve, water level, wind, weather, radar, and sun & moon times together — instead of checking five different sites before you head out. It also names the thing most tide apps leave out: the slack, the stretch either side of a turn when the water barely moves. Free on the web; the iPhone, iPad and Apple Watch app adds saved places, widgets, a Lock Screen tracker, tide alerts, a month-ahead calendar, and the tide on your wrist.
Slackwater pulls the tide tables, the marine forecast, the radar, the sea state, and the sun & moon times into a single view — so planning a morning on the water takes seconds, not a browser full of tabs.
A clean grayscale map of every NOAA tide station on the U.S. coast — 3,600+ in all. Search by name, or tap "near me" to jump to the closest gauges. Layer on animated wind, radar, sea state, and any active marine alert areas.
Tap any station for its current tide status — the observed water level set beside the prediction, so a wind tide is obvious at a glance — a scrollable tide curve with two days of history behind you, the next highs and lows, and water temperature with its 24-hour trend.
The tide doesn't turn on a dime. On a diurnal coast the water can sit nearly still for hours around a high, and a countdown to the peak never tells you that. Slackwater reads those stretches off the predicted curve and lists each one on the station — when the water goes slow, and for how long — shaded on every curve.
Current wind speed, gusts, and direction with a 12-hour outlook, barometric pressure and its trend, sky conditions, and an hourly meteogram for the next 24 hours. The radar layer scrubs two hours back through observed frames and twelve hours forward through NOAA's HRRR forecast model.
Wave height with the swell and wind-wave split, each with its own direction and period — so a "four foot" day reads the way it actually feels. Small Craft Advisories, gale warnings, and other marine alerts appear on the station and as areas on the map.
Sunrise, sunset, moonrise, and moonset for the station's exact location and timezone, plus the moon phase and illumination. Major and minor solunar periods are computed on-device, with a rating for each day.
A month of days at a glance, or expanded one at a time: the day's tide sparkline, high and low times, the weather range, wind, sun and moon, moon phase, and a fishing rating — so picking the right morning takes one screen.
Four widgets — Tide Now, Station Board, Window, and Day Board — each set to whichever station you want, drawing the measured water over the prediction so the difference reads at a glance. Start the Live Activity from a station, Control Center, or a Shortcut and the level, direction, and countdown to the turn follow you on the Lock Screen and in the Dynamic Island.
Save the spots you check most; each one shows its level, next turn, slack window, and curve in a single row. Optional alerts arrive ahead of the slack window rather than the turn, alongside solunar reminders, a morning brief, and marine advisories — all scheduled on your device, with quiet hours.
The tide on your wrist: the water level against the prediction, where you are in the cycle with the slack shaded, and the next turn counting down. Turn the Digital Crown to scrub the curve a full day back. Complications for every face show the level, the trend, and a cycle gauge; Smart Stack cards carry the tide and the curve; and a tide you start tracking on your iPhone follows you to the watch. Favorites sync from the phone, and the last tide stays cached for when you're out of range.
Slackwater shows you the coast without asking anything of you. There's no sign-in, no advertising, and no analytics SDKs. Your saved places and preferences stay on your device.
No accounts or sign-ins
No ads or advertising identifiers
No third-party analytics or tracking SDKs
Saved places & settings stay on your device
Location is used only to place you on the map
Alerts are scheduled on your device — no push server
Your watch syncs from your iPhone — nothing leaves your own devices
We never sell or share your data
Tide predictions, water levels, and station weather.
Forecasts and current observations.
Sun & moon rise/set times and moon phase.
Wind and precipitation forecast grids.
Observed weather radar tiles.
Forecast radar, via the Iowa Environmental Mesonet.
The base map and tiles.
The whole dashboard is free at slackwater.app, no account required. One subscription covers the iPhone, iPad and Apple Watch app — saved places, widgets, the Lock Screen tracker, tide alerts, the month-ahead calendar, and the watch — for the price of a coffee a month, or less than one a season by the year.
Slackwater is for general information and recreation only. Do not rely on it for navigation, marine safety, or any decision affecting life, health, or property. Tide values are predictions and weather data can be delayed or estimated; actual conditions may differ. For navigation and any safety-related decision, always consult official NOAA tide tables and charts, National Weather Service marine forecasts, and the U.S. Coast Guard, and use your own judgment.
Bug reports, feature requests, real questions — they all land in my inbox. No queue, no ticket system, no bot.