Apra Harbour, Guam · Pacific/Guam

Piti Bomb Holes

Three passes cut through the reef flat. The middle one has the steepest face on the island and goes completely hollow when the tide is over the shelf.

00:00 local · 2026-10-05

64% — the read for this hour

Worth the drive64%

Swell

1.26 m

Period

8 s

Swell from

336°

Wind

7.6 m/s

Wind from

230°

Air

27°C

Worth the drive64%

Worth the drive. At Piti Bomb Holes on this hour the read is 64%. What earns it: peel speed at 15.9 km/h. What costs it: direction match at 172° off the 148° peel.

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.

Piti Bomb Holes · 24 hours, local timelive data

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: Apra Harbor, Guam
Datum: MLLW
Range: 0.78 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 · Piti Bomb HolesReef pass — a channel cut through the outer barrier reef

Drag the tide — what-if only, nothing stored is changed

0.60 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 64%seal 551e22b36dc1…

Water over take-off: exposed
Break height: 0.71 m
Peel speed: 15.9 km/h
Wave power: 8.1 kW/m

Worth the drive. At Piti Bomb Holes on this hour the read is 64%. What earns it: peel speed at 15.9 km/h. What costs it: direction match at 172° off the 148° peel.

Every factor, re-weighted for this tide

Swell power8.1 kW/m · 8.1%
Peel speed15.9 km/h · 20.0%
Wind quality7.6 m/s 106° off · 12.7%
Tide window2.00 m over the take-off · 18.0%
Direction match172° off the 148° peel · 0.0%
Period cleanliness8.2 s · 5.3%

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 power8.1 kW/m · 8.1%
weight 0.220
Peel speed15.9 km/h · 20.0%
weight 0.200
Wind quality7.6 m/s 106° off · 12.7%
weight 0.200
Tide window2.00 m over the take-off · 18.0%
weight 0.180
Direction match172° off the 148° peel · 0.0%
weight 0.120
Period cleanliness8.2 s · 5.3%
weight 0.080

engine seal 551e22b36dc13199e1cacfaa8fb7dab1aa8dcaaca4da5adbf90193a2ab150bb7fcfeb2f7e300dc64e71d9b49df9b6caa

Swell power
P = 1/16 · rho · g · Hs² · Tp = 0.628 · 1.26² · 8 = 8.1 kW/m, against a 22 kW/m "serious day" reference.
Peel speed
c = sqrt(g · depth) = sqrt(9.81 · 2.00 m) = 15.9 km/h over a 2.00 m take-off, with 0.71 m standing up. Full marks 8.5–19 km/h: slower is mush, faster than ~25 km/h is unridable.
Wind quality
Wind is 106° off at 7.6 m/s. Alignment = 1 − (1 + cos 106°)/2 = 0.64; speed envelope at 7.6 m/s = 1.00. Product 0.64.
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 336°, this break peels cleanly from 148°. 172° of error: inside 12° is full marks, past 75° the swell wraps the headland and does not arrive.
Period cleanliness
Tp = 8.2 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

liveOpen-Meteo Marine APICC BY 4.0, non-commercial attribution requiredfetched 2026-10-04 19:52 UTC168 hourly rows, swell and wind wave.
liveOpen-Meteo Forecast APICC BY 4.0, non-commercial attribution requiredfetched 2026-10-04 19:52 UTC168 hourly rows, wind and air.
liveNOAA CO-OPS tide predictionsU.S. Government public domainfetched 2026-10-04 19:52 UTC144 hourly predictions, MLLW datum, station 1630000 (Apra Harbor, Guam).

Snapshot generated 2026-10-04T19:52:54.950Z. Break orientation, reef slope and take-off depth come from this project's catalogue and are labelled as estimates, not survey data.