Tideturn

The tides for the harbours and beaches you care about, on iPhone. This is the beta. It works, it isn't finished, and I'd like to hear what you think.

The list of saved places, each in its own sky — Every place in its own sky

A station's screen with the tide now and the day's curve — The tide now, and the day

Weather and water at the station — Weather and water

Search for a beach or a town — Search for a beach

Honolulu Harbor at dusk — Anywhere in the world

What it does

Glance at the list. Each place you save is a card with the height now, the curve around now, and a countdown to the next high or low.
Tap for the day. The tide table, a curve you can hold and drag through the day, sunrise and sunset, the moon, the weather, the water temperature and waves, and whether the beach is safe to swim.
Search for where you're going. A beach, a bay, a town, or a tide station. A place borrows the tide from the nearest station and always says which.
Works offline. Everything comes from what's on your phone. With no signal you still get the tides it last downloaded, and anywhere outside the US and Canada they're computed on the phone.
Says how good the number is. Every station says where its tides come from and how much to trust them. When there's no real answer, it says so rather than guess.
A widget for your Home Screen and Lock Screen.
Private. No account, no ads, no tracking. Location is approximate and optional.

Predictions come from NOAA and the Canadian Hydrographic Service, and elsewhere are computed from published harmonic constants. They are predictions, not observations, and not for navigation.

What to test. Find your harbour. Check tonight's highs and lows against the marina board or the tide table you trust. Turn on Airplane Mode and check they're still there. Add the widget and look at it again in three days: it should still be right, or say plainly that it has run out. Take a screenshot in the app and tap Share Beta Feedback, or email support@tideturn.app.

Look closer

Screens: every screen, and what each part does.
Sky: why the background changes with the time and the weather.
Design System: the rules every screen follows.

The icon is the app's own tide curve in four skies. Dawn ships; the other three are ready for a picker.