What the Tide Chart Shows
The tide chart on the TankRainBDA homepage pulls live predictions from NOAA CO-OPS station 2695540 at St. Georges Island — one of the few tide gauges producing continuous public predictions for Bermuda. The curve shows predicted water height in feet above mean lower low water (MLLW), the baseline used on US nautical charts. Dots mark predicted high and low turning points; a vertical line marks the current moment on the curve.
The chart spans ~48 hours, enough to see the full tidal rhythm and plan two days ahead. The pattern is semi-diurnal: two highs and two lows per day.
Bermuda's Tide Cycle: Semi-Diurnal
Bermuda's tides repeat every 24 hours and 50 minutes — not 24 hours exactly — because they're driven by the moon, whose day is 50 minutes longer than the solar day. Each tide therefore arrives about 50 minutes later than the day before. A low tide at noon on Monday will have migrated to late evening by Friday, the wrong end of the day for a reef walk.
The two daily cycles also differ slightly in height — diurnal inequality — driven by the moon's angle relative to the equator. On the chart this shows up as one peak slightly taller than the other.
Bermuda's Tide Range: Why It's Smaller Than You Expect
Bermuda's tidal range, the difference in water height between low and high tide, typically runs between 2.5 and 3.5 feet. To put that in context: the Bay of Fundy in Nova Scotia sees ranges of over 50 feet, and parts of the English coast — the Bristol Channel in particular — average over 30 feet and can reach 49 feet. By contrast, most Caribbean islands — Barbados included — see ranges of just 1–3 feet, similar to or smaller than Bermuda's.
Bermuda's modest range comes down to geography. Tidal amplitude amplifies in narrowing estuaries and over broad continental shelves. Bermuda is a seamount ringed immediately by deep open ocean with no shelf to amplify the tidal wave — the tide rolls across the Atlantic and the island barely interrupts it.
That small range still matters on the water. On a spring tide the range can reach 3.5 feet — enough to strand a dinghy over a reef flat or open up reef walking that isn't possible at mid-range.
Spring Tides vs. Neap Tides
Spring tides occur at every new and full moon, when the sun, Earth, and moon align and their gravitational pulls stack. The result is the month's biggest range: higher highs and lower lows. In Bermuda a spring low can expose reef flats that are normally underwater — prime windows for reef walking, hand-line fishing, and fast tidal flow through cuts and channels.
Neap tides occur at the first and third quarter moons, when the sun and moon are at right angles and partially cancel. The range shrinks to roughly 1.5–2 feet — barely noticeable, but enough to limit reef access that a spring low would allow.
What Tides Mean for Daily Life in Bermuda
Reef snorkelling peaks around low tide — sites like Tobacco Bay, Church Bay, and Devil's Hole become shallower, calmer, and easier to read. The ideal window is one hour either side of the predicted low; a spring low exposes the most bottom.
Reef cuts and dinghy passages — Harrington Sound, Castle Harbour channels — have marginal depths that shift with the tide. Know the tide stage before attempting any shallow passage, especially for vessels drawing more than 3 feet. Note that NOAA predicts for St. Georges Harbour; inshore reef flats may differ.
Fishing is most productive in the two hours either side of a tide change, both high and low, when shifting currents push bait fish and predators position on structure. Many local anglers plan outings around the tide table, not the clock.
Horseshoe Bay surf changes with tide stage. Lower water brings shallower reef sections and harder-breaking waves; higher water shifts the break over sand. Check tide alongside swell height and direction.
Tides and Storm Surge
NOAA's tide predictions are astronomical — they account for the moon and sun, not weather. When a hurricane or strong nor'easter crosses Bermuda, low atmospheric pressure and onshore winds can push several additional feet of water above the predicted level. This weather-driven rise, storm surge, is additive on top of the predicted tide.
A storm arriving at spring high tide is significantly more dangerous than the same storm at neap low tide. Emergency managers watch the tide table alongside the storm track for exactly this reason. Check both the storm forecast and the predicted tide for the expected arrival window. See the Bermuda Hurricane Season Guide for the full pre-storm checklist.
How to Use the Live Chart on TankRainBDA
A simple workflow for planning a day on the water using the tide chart on the homepage:
- Find the "now" line. Read across to the y-axis to get current predicted water height above MLLW.
- Locate the next hi/lo dot. That's your next turning point. For reef snorkelling, target a low dot.
- Check the trend. Rising or falling? Factor that in for shallow passages in the next 30–60 minutes.
- Plan around the turning point. The best windows are one to two hours either side — not at the exact turning point (minimal current) and not mid-tide (current running hardest through cuts).
- Check tomorrow's lows. The 48-hour chart lets you compare windows across two days and judge whether you're on a building or ebbing spring cycle.
For raw hourly predictions up to a year ahead, see NOAA station 2695540 at St. Georges.