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Swellread

Kauaʻi, United States · Pacific/Honolulu

Hanalei Bay

No NOAA tide station in range, so Swellread refuses to score the tide factor here. Read the window, know that something is missing, do not invent it.

Part of this page is live and part is not.

See the source list at the bottom for exactly which feed answered.

11:00 local · 2026-10-04

12% — the read for this hour

Stay home12%

Swell

0.70 m

Period

6 s

Swell from

14°

Wind

4.5 m/s

Wind from

75°

Air

25°C

Stay home12%

Stay home. At Hanalei Bay on this hour the read is 12%. What earns it: wind quality at 4.5 m/s 61° off. What costs it: direction match at 90° off the 104° peel. Not scored, because no real data exists: Peel speed, Tide window.

No hour today clears the "worth the drive" bar at Hanalei Bay.

Tide window for a reef pass: 0.9–2 m of water over the take-off; below 0.60 m it needs the pass covered matters and the reef is exposed.

Hanalei Bay · 24 hours, local timemixed data
00:0003:0006:0009:0012:0015:0018:0021:00
score tide (dashed, MLLW) swell height nowno tide station in range

Dashed line is the tide above MLLW, solid line is the swell height. Column height is the engine score for that hour. Faded columns are gated. The hour you select is in the URL, so this page is shareable as-is.

Tide station

No tide station in range, so no tide value is shown anywhere in this app.

Signature interaction

Drag the tide and watch the reef change its mind

The cross-section is drawn from the break's own reef slope. Every change re-runs the shared engine on the server and returns a fresh seal — this control cannot work without the API.

Seabed cross-section · Hanalei BayReef pass — a channel cut through the outer barrier reef
take-off0m3m6m9m12m15moffshoreinshore · tanβ 0.12
0.84 m

The dashed arrow is the peel, at c = √(g·depth). More water over the take-off means a faster peel, which is why the same swell behaves differently at low and mid tide.

Re-solved by swellread-engine/2026.10.1

Stay home 12%seal f9d80a3bacc8…
Water over take-off
exposed
Break height
—
Peel speed
—
Wave power
1.9 kW/m

Stay home. At Hanalei Bay on this hour the read is 12%. What earns it: wind quality at 4.5 m/s 61° off. What costs it: direction match at 90° off the 104° peel. Not scored, because no real data exists: Peel speed, Tide window.

Every factor, re-weighted for this tide

  • Swell power1.9 kW/m · 3.1%
  • Peel speedneeds a tide height
  • Wind quality4.5 m/s 61° off · 8.3%
  • Tide windowno verified tide in range
  • Direction match90° off the 104° peel · 0.0%
  • Period cleanliness6.2 s · 0.1%

Show your working

Every factor, its weight, and the arithmetic behind it

Weights are renormalised over the factors that have real data behind them. A factor with no data is dropped and said so, never quietly scored at zero.

  • Swell power1.9 kW/m · 3.1%

    weight 0.355

  • Peel speedneeds a tide height

    weight 0.000 — dropped, not guessed

  • Wind quality4.5 m/s 61° off · 8.3%

    weight 0.323

  • Tide windowno verified tide in range

    weight 0.000 — dropped, not guessed

  • Direction match90° off the 104° peel · 0.0%

    weight 0.194

  • Period cleanliness6.2 s · 0.1%

    weight 0.129

engine seal f9d80a3bacc8302330528e9680b384d6cd3bd0a3e5463e0fa1a7cb5b88c667afc06c70939a954196a6b079d2399195bf

  • Swell power

    P = 1/16 · rho · g · Hs² · Tp = 0.628 · 0.70² · 6 = 1.9 kW/m, against a 22 kW/m "serious day" reference.

  • Peel speednot scored

    Peel speed is shallow-water celerity, so without a verified tide height there is no depth to take the square root of. This factor is dropped rather than guessed.

  • Wind quality

    Wind is 61° off at 4.5 m/s. Alignment = 1 − (1 + cos 61°)/2 = 0.26; speed envelope at 4.5 m/s = 1.00. Product 0.26.

  • Tide windownot scored

    This break has no NOAA CO-OPS tide station in range, so the tide window cannot be scored. Weights are renormalised without it instead of substituting a guess.

  • Direction match

    Swell from 14°, this break peels cleanly from 104°. 90° of error: inside 12° is full marks, past 75° the swell wraps the headland and does not arrive.

  • Period cleanliness

    Tp = 6.2 s. Energy organises between 6 s and 9.5 s; beyond 14 s the swell stands up steeper than a shallow reef can hold, so the score is eased off by up to 35%.

Provenance

Every number above came from one of these

Snapshot generated 2026-10-04T20:30:42.758Z. Break orientation, reef slope and take-off depth come from this project's catalogue and are labelled as estimates, not survey data.

Hanalei Bay, Kauaʻi · Swellread