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Swellread

Tutuila, American Samoa · Pacific/Pago_Pago

Pago Pago

The harbour mouth stands up out of the barrier reef and peels hard left on a big south pulse. It is the reason this app exists: the numbers that make it work arrive days before anyone can see them.

04:00 local · 2026-10-04

69% — the read for this hour

Worth the drive69%

Swell

1.28 m

Period

8 s

Swell from

174°

Wind

9.2 m/s

Wind from

116°

Air

26°C

Worth the drive69%

Worth the drive. At Pago Pago on this hour the read is 69%. What earns it: peel speed at 14.9 km/h. What costs it: wind quality at 9.2 m/s 58° off.

24 hours worth driving for today: 00:00, 01:00, 02:00, 03:00, 04:00, 05:00, 06:00, 07:00, 08:00, 09:00, 10:00, 11:00, 12:00, 13:00, 14:00, 15:00, 16:00, 17:00, 18:00, 19:00, 20:00, 21:00, 22:00, 23:00.

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.

Pago Pago · 24 hours, local timelive data
00:0003:0006:0009:0012:0015:0018:0021:00
score tide (dashed, MLLW) swell height now

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

Station
Pago Pago, American Samoa
Datum
MLLW
Range
0.97 m
Mean
0.43 m

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 · Pago PagoReef pass — a channel cut through the outer barrier reef
take-off0m3m6m9m12m15moffshoreinshore · tanβ 0.11
0.65 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

Worth the drive 69%seal d99378f2811e…
Water over take-off
exposed
Break height
0.69 m
Peel speed
14.9 km/h
Wave power
8.7 kW/m

Worth the drive. At Pago Pago on this hour the read is 69%. What earns it: peel speed at 14.9 km/h. What costs it: wind quality at 9.2 m/s 58° off.

Every factor, re-weighted for this tide

  • Swell power8.7 kW/m · 8.7%
  • Peel speed14.9 km/h · 20.0%
  • Wind quality9.2 m/s 58° off · 4.2%
  • Tide window1.75 m over the take-off · 18.0%
  • Direction match19° off the 155° peel · 11.6%
  • Period cleanliness8.4 s · 6.1%

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 power8.7 kW/m · 8.7%

    weight 0.220

  • Peel speed14.9 km/h · 20.0%

    weight 0.200

  • Wind quality9.2 m/s 58° off · 4.2%

    weight 0.200

  • Tide window1.75 m over the take-off · 18.0%

    weight 0.180

  • Direction match19° off the 155° peel · 11.6%

    weight 0.120

  • Period cleanliness8.4 s · 6.1%

    weight 0.080

engine seal d99378f2811ee09af3c4361a5097276fedb4b328b8c22777be70c9189872f712f88041b34693642fd386d9e28baa0032

  • Swell power

    P = 1/16 · rho · g · Hs² · Tp = 0.628 · 1.28² · 8 = 8.7 kW/m, against a 22 kW/m "serious day" reference.

  • Peel speed

    c = sqrt(g · depth) = sqrt(9.81 · 1.75 m) = 14.9 km/h over a 1.75 m take-off, with 0.69 m standing up. Full marks 8.5–19 km/h: slower is mush, faster than ~25 km/h is unridable.

  • Wind quality

    Wind is 58° off at 9.2 m/s. Alignment = 1 − (1 + cos 58°)/2 = 0.24; speed envelope at 9.2 m/s = 0.89. Product 0.21.

  • Tide window

    reef pass needs the pass covered. Ideal band 0.9–2 m of water over the take-off; below 0.60 m the reef is exposed.

  • Direction match

    Swell from 174°, this break peels cleanly from 155°. 19° of error: inside 12° is full marks, past 75° the swell wraps the headland and does not arrive.

  • Period cleanliness

    Tp = 8.4 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 2026-10-04T19:09:21.263Z. Break orientation, reef slope and take-off depth come from this project's catalogue and are labelled as estimates, not survey data.

Pago Pago, Tutuila · Swellread