How this works
Two levels on the crossing, one band of light, and a rule that fits in a sentence.
1 · The crossing
The Wingaersheek bar is a spit joined to the beach by a low saddle. Mapping NOAA's 1/9-arc-second
coastal elevation model of the flats puts that saddle at roughly 1.4 ft above MLLW, while
the bar's own spine runs a foot or two higher — so there's a real window where the bar is bare sand and
the neck you cross is still shin-deep. Two levels matter: below about 1.9 ft the crossing
is ankle-deep at most and you can simply walk it; below about 3.4 ft it's a wade, up to
roughly thigh-deep. Deeper than that and the bar is effectively an island. Those are the two bands on the chart.
2 · The rule
A rating is a statement about where the tide curve sits relative to the two crossing levels and the
golden band. Nothing is weighted or averaged; an evening either satisfies a rule or it doesn't.
Three suns — golden hour opens while the crossing is in the wadeable band (under
wade, still over walk), and the half hour after sunset is walkable throughout. Nothing is required of
the half hour before sunset; that's when the wading happens.
Two suns — the half hour either side of sunset is walkable throughout.
One sun — that same hour is wadeable throughout.
Anything else is left off the list.
3 · The light
Sunset is computed for the beach itself (42.650° N, 70.684° W) with NOAA's solar algorithm, checked
against the US Naval Observatory. The golden band on the chart is the seventy minutes before the sun goes down.
Why it can see so far ahead
Tides are astronomy. Predictions come from NOAA's harmonic forecasts for station
8441571 — Annisquam,
Lobster Cove, a mile up the river from the flats, and run through December 2040.
Three suns means the evening has the full shape described above — about twenty-three a year,
ten of them in swimmable weather. Use the date box above to pull up any evening, including the
ones that don't make the list, and see for yourself.
A note from the sea: the flats flood from the edges first when the tide turns, and
faster than you'd think. The saddle you crossed is the first thing to go. Wander far, but keep an eye
on the channel behind you.
Honest about error bars: the saddle height carries roughly ±0.4 ft of datum uncertainty,
the elevation survey dates from 2021, and sandbars migrate — so treat the depths as a good guide, not a
guarantee. Predictions also ignore weather entirely: wind, storm surge, and clouds on the horizon do
what they like. Times are local to Gloucester. Compiled July 2026.