Tide slink

Planning a day on the flats comes down to one question: when exactly is the water low enough, long enough, and in daylight. Tidekeeper answers it without ever touching the network. Today Pick a station and the whole day is laid out: the tide curve drawn from the actual harmonic sum, the next high and low with heights, the dry window around the low, a tide summary, and the moon phase with its position in the spring–neap cycle. Heights are given against the datum you choose — MLLW, LAT, MSL, MLW or your own offset. Windows This is the part that matters for beachcombing, tide pooling, photography, fishing or getting a boat off a ramp. Set a purpose and Tidekeeper finds every stretch of the day that drops below your threshold, lasts at least as long as you need, and falls inside daylight. Six built-in purposes carry sensible defaults; adjust the threshold, minimum duration and daylight rule and they become yours. Each window is scored and ranked, and a safety buffer is trimmed off the end so you are walking back while the water is still below your ankles, not racing it. Calendar A month at a time, with the day's highs and lows and a bar showing where the range sits between springs and neaps. Scan for the week with the biggest daytime low and plan further out. Stations Ninety reference stations across thirty-four countries, searchable by name or region, with tide type, datum and coordinates. You can add your own, or derive a subordinate station from a reference one using time differences and a height ratio — the way paper tide tables have always done it. Reminders and export Ask to be told before the next high or low, when a window opens, or before the turn deadline. Export a two-page A4 tide table for any month: the full daily table, spring–neap bars, and a single day's curve. How it works The tide is expanded into ten constituents — M2, S2, N2, K2, K1, O1, P1, Q1, M4, MS4 — with the Delaunay lunar arguments evaluated at the J2000 epoch. High and low water are found by scanning the curve in three-minute steps and bisecting on its derivative, then refined to a fraction of a minute. Sunrise and sunset come from the same astronomical core, so a daylight-only window means daylight at that station, on that date. Three colour themes, metric or imperial units, station-local or device time, and native charts. Requires iOS 15.0 or later. Coordinates and mean ranges are published figures; constituent amplitudes are derived from mean range and tide type, and epoch phases are synthetic. Predictions are for planning, not for navigation — always check the local tide table and the sky before you go out.

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