WRACKLINE
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Version 4.6: surge watch is here

Tide times you can plan a passage on.

Wrackline shows the height of the water, minute by minute, for the stretch of coast you use. It works with no signal, needs no account, and tells you when the weather will throw it off.

Get it on iPhone Get it on Android
4.8 from 9,300 ratings Free to download. Pro from £18 a year.

Try it here

Pick a port and read today’s water.

This is the chart the app draws, computed in your browser for today. The lime line is now.

All six ports

Halberry Roads

Sunday 4 October

Heights in metres above chart datum

00:0003:0006:0009:0012:0015:0018:0021:0024:002 m4 m6 m8 m01:14 · 2.4 m07:15 · 8.2 m13:50 · 2.6 m19:42 · 8.2 m
  • Low water01:142.4 m
  • High water07:158.2 m
  • Low water13:502.6 m
  • High water19:428.2 m

Between neaps and springs · range 5.7 m

Open the Halberry Roads page

Four ways to read a tide

Sailors, anglers, surfers and walkers each need a different answer

Same prediction, four questions. Wrackline answers the one you are asking.

Sailors: plan a passage around the tide

For sailors

Plan a passage around the tide

  • Window finder for any drying height
  • Hours of flood and ebb, marked on the curve
  • Surge watch when a low is sitting on the coast
Anglers: be on the mark for the flood

For anglers

Be on the mark for the flood

  • Alerts at any point in the tide
  • Moon phase and springs or neaps at a glance
  • Dawn and dusk overlaid on the curve
Surfers: know when your break switches on

For surfers

Know when your break switches on

  • Height bands per saved spot
  • Pushing or dropping, shown with the height
  • Lock-screen widget for the next session
Walkers: get back before the water does

For walkers

Get back before the water does

  • Turn-back time with a safety margin
  • Low-water walks planned days ahead
  • Works on a cliff path with no signal
See every feature

Ports

Which port are you heading for?

Six reference ports, each with its own page: the curve, the week ahead, and last year’s error in centimetres.

Request a port
Boats sitting on the harbour floor inside the stone pier at low water, with the town across the bay

Halberry Roads

Walled harbour, open coast

Spring range
7.9 m
Tide
Semidiurnal
Avg. error
11 cm
Yachts resting on sandbanks either side of a shallow channel at low tide, with red mooring buoys

Skellow Bar

Barred entrance

Spring range
5.3 m
Tide
Semidiurnal
Avg. error
19 cm
Small motor boats lying on the mud of a walled estuary basin at low tide, mooring lines slack

Nethermill Reach

Estuary basin on soft mud

Spring range
6.3 m
Tide
Semidiurnal
Avg. error
23 cm
Calm blue water in a sound between low rocky islands, with dark seaweed-covered ledges showing at low tide

Cargreave Sound

Deep sound, mixed tide

Spring range
1.7 m
Tide
Mixed
Avg. error
8 cm
A long rocky shore uncovered at low tide below green cliffs and a small town on the headland

Ossett Head

Rocky headland

Spring range
4.3 m
Tide
Semidiurnal
Avg. error
9 cm
Wide sand flats and a shallow channel at low tide, with a lighthouse and headland in the distance

Feltwater Ness

Sand flats, small range

Spring range
0.7 m
Tide
Mixed
Avg. error
14 cm
Small boats lying on the mud of a walled harbour at low tide, mooring lines slack

Accuracy

How far off is a tide table?

Usually a hand’s width. Sometimes a metre, when the weather leans on the sea. We publish both numbers for every port, and flag the days it will happen.

Average error
14 cm
Readings a year
87k
Recalibrated
Yearly
Read the accuracy report

How it works

From a harbour wall to your lock screen

A year of gauge readings becomes eight numbers per port. Your phone does the rest.

A tide gauge logs the water level at the port every six minutes for at least a full year.

Measured

A tide gauge logs the water level at the port every six minutes for at least a full year.

That record is broken into eight harmonic constituents: the moon, the sun, and the shape of the coast.

Solved

That record is broken into eight harmonic constituents: the moon, the sun, and the shape of the coast.

Each port is re-checked against the gauge every year, and the error is published on its page.

Checked

Each port is re-checked against the gauge every year, and the error is published on its page.

The constants ship inside the app, so your phone computes any day of the year with no signal.

Carried offline

The constants ship inside the app, so your phone computes any day of the year with no signal.

Pricing

Free for today. £18 a year for the whole year.

No adverts in either. Pro starts with a 14-day free trial and cancels in two taps.

  • 14 days free. Every Pro feature from the first minute; nothing is charged until the trial ends.
  • Cancel in two taps. From your App Store or Google Play account, no email needed.
  • One price, every port. No regional packs and no add-ons, including ports we add later.

Free

£0forever

Today and tomorrow at any port. Enough for a walk or a quick launch.

  • High and low water times and heights: today and tomorrow
  • Tide curve with a live "now" marker
  • Sunrise, sunset and moon phase
  • Saved ports: 1
Download free

Pro

14-day free trial

£18a year, billed once

£2.99a month, cancel any time

The whole year ahead, offline, with alerts that wake you before the water turns.

  • Everything in Free, for 365 days ahead
  • Tide alerts
  • Window finder
  • Surge watch
  • Home-screen and lock-screen widgets
  • Printable tide tables and calendar export
Start your free trial

Club licence: Pro for up to 40 members of a sailing club, angling club or surf school, on one invoice. £210 a year. Ask about a club licence

Free and Pro compared, feature by feature
What you get Free Pro
High and low water times and heights Today and tomorrow 365 days ahead
Tide curve with a live "now" marker Included Included
Sunrise, sunset and moon phase Included Included
Saved ports 1 Unlimited
Works with no signal Every prediction is computed on the phone Included Included
Tide alerts For example, 90 minutes before low water Not included Included
Window finder When is there 1.8 m over the bar? Not included Included
Surge watch Flags days when pressure and wind will move the water Not included Included
Home-screen and lock-screen widgets Not included Included
Printable tide tables and calendar export Not included Included
Adverts None, ever None, ever

Reviews

4.8 stars from 9,300 ratings

What people write in the store after a season on the water.

5 out of 5 stars iPhone

Finally trust the bar crossing

The window finder tells me when there is 1.8 m over Skellow Bar, and it has been right to within ten minutes all season. I stopped doing the rule of twelfths on the back of a chart.
@moorings_and_mud
5 out of 5 stars Android

Works in the dead zone

No signal on our stretch of cliff at all. Wrackline does not care, the whole year is already on the phone.
@headland.walks
5 out of 5 stars Android

The alert is the feature

Set it for two hours into the flood and it buzzes while I am still making coffee. That is when the bass come in over the rocks here, and I have not missed it since.
@rockmark_rob
5 out of 5 stars iPhone

Honest about its limits

It told me a big low was sitting on the coast and the tide would run 30 cm high. It did. No other app I have used even mentions the weather.
@westerly_sailor
5 out of 5 stars iPhone

Clean, fast, no adverts

Opens straight to my port and the curve. No splash screen, no sign-up, no pop-ups asking me to rate it. So here I am rating it.
@j.tolland
5 out of 5 stars iPhone

Surf check in one glance

Our reef only works on a pushing tide between about 1.5 and 3 metres. The widget shows exactly that band on my lock screen.
@lowreef_lou
4 out of 5 stars Android

Club licence was painless

Forty members, one invoice, set up in an afternoon. The juniors use the free version for their dinghy days and it is plenty.
@ossettsc_bosun
5 out of 5 stars Android

Causeway timing sorted

We walk out to the island most weekends. The "turn back by" time is the first thing I look at now.
@two_dogs_one_causeway
4 out of 5 stars iPhone

Wish it had more ports

Brilliant for the six stations it covers. My home harbour is not on the list yet, but they answered my request within a day and it is on the roadmap.
@estuary.fern

Journal

Guides, and what shipped lately

All articles
A red dinghy tied below a harbour wall, with a dark band of seaweed marking the high-water line

Accuracy 6 August 2026 · 5 min read

The night Feltwater Ness had no low water

A neap, a hard south-westerly and 992 millibars. The prediction said 0.4 m at low water and the gauge never came below a metre. Here is why that was not a bug.
Two yachts and a small motor boat sitting upright on a wide sand flat at low tide

Guides 18 July 2026 · 6 min read

Reading a tide curve before you launch

The rule of twelfths works on a textbook coast. Here is how to read the real curve instead, and why it matters at a barred harbour or up an estuary.

Changelog

Every release

  1. v4.6

    Surge watch reads the barometer

  2. v4.5

    Turn-back times for causeways

  3. v4.4.2

    Widget refreshes on time

  4. v4.4

    Height bands for surf spots

Questions

Questions, sorted by what you do on the water

Pick your tab. Anything else goes to the duty phone, answered by the people who build the app.

All questions

Questions from sailors

Can I plan a passage on Wrackline?

You can plan around it: times, heights and the window over a bar or a drying mooring. For navigation itself, use official tables and your chart. Every prediction ignores weather, and the surge watch flag tells you when that matters.

How does the window finder work?

Enter the depth you need and the charted drying height. Wrackline shows every window in the next 12 months when the predicted height clears it, with your margin shaded.

Does it show tidal streams?

Not yet. Streams depend on local charted data we have not licensed. The hours of flood and ebb are marked on the curve, and streams are on the roadmap in the changelog.

Can the whole crew use one subscription?

Pro follows your store account, so it works on your own phones and tablets. For a club or a school, the club licence covers up to 40 people on one invoice.

Questions from anglers

Can I get an alert at a set point in the tide?

Yes, with Pro. Pick any point, for example two hours after low water or 30 minutes before high water, and Wrackline alerts you on every tide or only on the days you choose.

Does it show springs and neaps?

Every day is labelled on a scale from neaps to springs, and the moon phase sits beside it. The range for the day is shown in metres too.

Is sunrise and sunset included?

Yes, in the free version. Dawn and dusk are shaded on the curve so you can see where the best tide meets the best light.

Does it work on a rock mark with no signal?

Yes. Every prediction is computed on the phone, in both versions, so a rock mark with no signal is no problem.

Questions from surfers

Can I save the tide my break needs?

Yes. Save a spot with its height band, say 1.5 to 3 metres on a pushing tide, and the band is shaded on the curve and shown on the widget.

Does Wrackline forecast swell?

No. It does tides, and does them well. Use your usual swell forecast alongside it; the two answer different questions.

Is there a lock-screen widget?

Yes, with Pro, on iPhone and Android. It shows the current height, whether the tide is pushing or dropping, and the next high or low.

How accurate are the heights?

Typically within 10 to 25 cm on an ordinary day. Each port page publishes last year’s average error and the single worst day.

Questions from walkers

What is the "turn back by" time?

For a causeway or a tidal island you save, Wrackline works out when the rising water reaches the path and subtracts a safety margin you choose. We suggest at least an hour.

Is the free version enough for walks?

For most walks, yes: today and tomorrow at every port, with the curve, times and heights. Pro adds walks planned weeks ahead and alerts.

Does it need a signal on the coast path?

No. Every prediction is computed on your phone, free or Pro, so the app works on a cliff path with no bars at all.

Do you cover my beach?

The app covers six reference ports and the coast between them. If you need a new port, send a request and we reply within a working day.