Hold your iPhone up and point it at the sea where the swell is coming from. Read the bearing off the compass card in the center of the screen—N/E/S/W or degrees. The bearing updates as you turn. Tap Record to save it.

Go to the Period screen and tap once each time a wave peak passes in front of you. After 3 taps (2 intervals), SwellBearing shows a period in seconds. Keep tapping to refine it. The app finds the median of your intervals, so a missed tap or accidental double-tap won't throw it off.

On the Height screen, aim your phone at the wave trough (bottom), tap Trough. Then aim at the crest (top), tap Crest. The app uses the angle difference and basic trigonometry to calculate height. Aim carefully—even 0.3° makes a 15cm difference.

From the period you measured, the app calculates speed (how fast a wave peak moves) and wavelength (distance between peaks). Both come from deep-water wave physics and are clearly labelled as deep-water values—the real speed near shore is slower because the water gets shallower.

Forecasts show predictions from other people's models. SwellBearing is your logbook—it records what you actually saw: bearing, period, height, size, and your spot. Over time, you'll see the pattern at each break and remember what the swell was really like.

Location is optional. When you save a spot (a named break), you can use your phone's current location. If you turn it off, you can still log bearing, period, and height—you'll just tag them to a spot you entered by name.

This app is a logbook for surfers, not a navigation tool. The compass is affected by metal and electronics nearby. Before you rely on a bearing, compare it to a landmark you trust. Never use this app alone for marine navigation.

In the first version, your entries stay on your phone. If you add notes to each session, you have a record in the app. Future versions may add export or backup—feature requests are welcome.