Your records stay yours
No account. Your watches live on your iPhone and in your own iCloud, with a backup file in Files every week and CSV or JSON export on every plan.
CrownwindSeconds a day and service log
Time your watch by eye.
Crownwind measures how many seconds a day each mechanical watch gains or loses. You tap as its seconds hand reaches 12; Crownwind shows true time, from your iPhone’s clock checked with Apple’s time server.
Two watches free, with unlimited syncs. Crownwind Plus adds every watch you own, for £1.99 a month or £12.99 a year.
Coming soon
How it compares
Cancel
Harrow Field 38
Clock checked: phone 0.21 s slow
06:46
28.3
Tap as your seconds hand reaches 12
Tap 2 of 3
Tap
32.5 s fastIts seconds hand reached 12 at 06:46:27.5+3.6 s/day over nine days
Sync
01
It checks the time first.
When Sync opens, Crownwind asks Apple’s time server how far your iPhone’s clock is out, then counts true time to a tenth of a second.
02
Tap as the seconds hand reaches 12.
Once a minute, three minutes running. You watch the watch, not the phone: the lower part of the screen is the button, and it takes the moment your finger lands.
03
Confirm the minute it showed.
A wheel opens on the minute your watch should be showing, worked out from its last sync and its rate. Confirm it, and the sync is saved.
Cancel
Harrow Field 38
Clock checked: phone 0.21 s slow
Checking the clock…
06:48
27.4
Tap as your seconds hand reaches 12
Tap 3 of 3
Tap
What minute did your watch show at your last tap?
06:4606:4706:4806:4906:5006:5106:52
Confirm
My watch showed another minute
The drift
Watch it drift, sync by sync.
Each sync adds a point: how far the watch has run from true time since you set it. The shaded cone is your target, so while the line stays inside it, the watch is within your target.
32.5 s fastFri 16 Oct
True time
+6 s/day
-4 s/day
Set Wed 7 OctYour target, -4/+6 s/day
Honest numbers
01
No rate until six hours have passed.
One sync is a starting point, not a rate. Crownwind tells you when the first rate will be ready, and that 24 hours gives the best one.
02
Every rate comes with its range.
Closer taps and checked clocks give a narrower range, and so does more time between the two syncs.
03
No signal? The sync still counts.
With no connection the sync is kept, marked “Clock not checked”, and the rate it gives has a wider range. Nothing runs on a server of ours.
Positions
Rate it position by position.
After a sync, say how the watch spent the time: worn, dial up, crown down, on a winder and the rest. With Plus, each position shows its own average once it has two intervals.
Worn
+3.8 ± 0.5 s/day
Dial up
+5.4 ± 0.8 s/day
Crown down
+1.9 ± 0.4 s/day
s/day+2.0+3.0+4.0+5.0+6.0
Harrow Field 38, Wed 7 to Fri 16 Oct. Each tick is one interval of 6 hours or more; the ring and its line are that position’s average and range.
Service log
01
Every service, kept.
The date, who did it, the cost, the work done and a note, for every watch you own.
02
Due by your interval, with a reminder.
Choose how often you have it serviced, and Crownwind reminds you 30 days before and on the day. The service log is part of Plus.
And the rest
Your records stay yours, and odd syncs are handled.
Rough taps, kept honestly
Taps more than a second apart? Try again, or keep it as rough and its rates show a wider range.
Set it, start a new run
Set your watch and say so: the next sync starts fresh, so the time you set it isn’t counted as drift.
Quartz watches too
The same taps measure a quartz watch, with its rate in seconds a month as well.
A changed clock is caught
If your iPhone’s clock was changed, or it restarted, between two syncs that weren’t both clock-checked, that interval is marked and left out of every average.
How it compares
Its service history, beside how it runs.
Plans
Measuring is free on two watches.
Free
£0
- Unlimited syncs, and every rate with its range
- The drift cone and the chart against your target
- Tag how each interval was spent
- A weekly backup, and CSV or JSON export
Crownwind Plus
£1.99 a month
or £12.99 a year
- Every watch you own
- The service log, with reminders from your interval
- Each position’s average rate
- If Plus ends, nothing is hidden or deleted
Questions
What people ask.
Does Crownwind listen to my watch?
No. There’s no microphone or audio recording anywhere in it. You tap as the seconds hand reaches 12, and Crownwind compares that with your iPhone’s clock, checked against Apple’s time server.
How soon do I get a rate?
Six hours after the first sync at the earliest, and 24 hours gives the best. After a first sync, Crownwind tells you the time the first rate will be ready.
Do I have to put my watch near my phone?
No. You don’t need to put your watch on or near your phone: you look at its seconds hand and tap the screen.
Does it work without a signal?
Yes. A sync with no connection is kept, marked “Clock not checked”, and the rates it gives have a wider range.
How much does Crownwind cost?
Two watches with unlimited syncs, rates, charts and export cost nothing, for good. Crownwind Plus is £1.99 a month or £12.99 a year, and adds every watch you own, the service log with its reminders, and position averages.
Is it a timegrapher?
No. It measures the rate over hours by eye, so it doesn’t give beat error or amplitude. Its results are measurements you make by hand: estimates, not a certification of any watch.
CrownwindSeconds a day and service log
Your watch’s first rate, by tomorrow.
Add your first watch, sync it this morning, and sync it again tomorrow.
Coming soon to iPhone