We make an anchor alarm app, so treat this as an informed but interested opinion. What follows is an honest framework for choosing one — the criteria that actually matter at 3am — and where the main options fit.
What actually makes a good anchor alarm
Before any brand names, these are the things worth judging an anchor alarm on. Most marketing ignores the first two, which are the ones that keep your boat off the rocks.
- Stays awake. It must keep monitoring with the screen off and the phone in your pocket or by the bunk. Foreground-only apps stop watching the moment the screen sleeps.
- Fails loud, not silent. If it loses its GPS fix, it should alarm — not quietly stop. Silent failure is the most dangerous behaviour an anchor alarm can have.
- Loud, persistent alarm that cuts through sleep and is not killed by Do Not Disturb.
- Sensible radius control so you can match the watch circle to your scope and swing.
- Low battery draw and a battery-saving mode for long nights.
- Sharing so crew or family ashore can keep an eye on the boat.
- Price that makes sense — ideally not a subscription for a safety tool you use seasonally.
At a glance
| App | Platform | Price model | Standout | Best for |
|---|---|---|---|---|
| HoldFast | iOS | Free · $4.99/yr · $9.99 lifetime | Alarms on GPS loss; browser remote watch | iPhone cruisers who want it simple and owned outright |
| Ankeralarm | iOS & Android | Freemium | Cross-platform | Mixed iOS/Android crews |
| Anchor Alert (PredictWind) | iOS & Android | Ecosystem | Weather + NMEA integration | Boats already in the PredictWind ecosystem |
| Anchor Sentry | iOS / iPad | Subscription | iPhone + iPad on one plan | Sailors who watch on a tablet at the nav station |
| SailGrib | Android | Paid | Offshore weather + drag algorithm | Hardcore offshore Android users |
| Chartplotter anchor watch | Onboard MFD | Included | Always powered | Boats with a good MFD and someone aboard |
The options in more detail
HoldFast
Our app. It was built around one principle: an anchor alarm should stay awake and should wake you if it ever loses confidence in its GPS fix, rather than going quiet. The free tier is a complete drag alarm with circular radius control, not a locked demo. Lifetime ($9.99, one payment) adds true background GPS, track history, custom boundaries, compass-bearing placement and a remote watch that lets anyone follow the boat from a browser with a short code — no app to install.
Trade-offs: iOS only, and it is deliberately focused on anchoring rather than being a full chart or weather suite.
Ankeralarm
A long-standing, well-regarded anchor watch available on both iOS and Android. If your boat runs a mix of phones, cross-platform support is genuinely useful and hard to find elsewhere.
Consider if you need the same app working on Apple and Android devices aboard.
Anchor Alert (PredictWind)
Part of the wider PredictWind weather and routing ecosystem, and integrates well if you already run their tools or NMEA-connected instruments. The anchor watch benefits from sitting alongside serious weather data.
Consider if you already live in the PredictWind world.
Anchor Sentry
Runs on iPhone and iPad, often on a single plan, which suits sailors who like to keep a big-screen anchor watch open at the nav station while the phone stays on charge.
Consider if you want an iPad display and do not mind a subscription.
SailGrib
Aimed at offshore sailors on Android, combining weather routing with a sensitive anchor-drag monitor that factors wind shifts into its logic. Powerful, but more than most coastal cruisers need just to keep an anchor watch.
Consider if you are an Android offshore sailor who wants weather and anchoring in one app.
Your chartplotter's anchor watch
If your boat has a modern multifunction display, its built-in anchor watch is always powered and needs no phone. The catch is that you must be aboard and awake to hear it, and the alarm is frequently too quiet to wake anyone in a forward cabin.
Consider it a good primary watch when aboard — and pair it with a phone alarm by your bunk.
How to choose
Cut through it with three questions:
- What phones are aboard? All iPhone — a focused iOS app like HoldFast or an iPad-friendly option. Mixed — go cross-platform.
- Subscription or one-time? If you anchor seasonally, a one-time purchase means the tool never lapses at the wrong moment.
- Do you need to watch from ashore? If crew or family will keep an eye on the boat, prioritise an app with easy sharing.
Whatever you pick, set it up properly — a great app with a badly chosen radius is worse than useless. Our guide to setting an anchor alarm walks through it.
Try HoldFast free tonight
A full drag alarm at no cost. Premium (background GPS, track history, remote watch) is $4.99 a year, or $9.99 once for Lifetime.
Download on theApp StoreFrequently asked questions
The best anchor alarm app is the one that keeps monitoring reliably with the screen off, alarms loudly, and warns you if it loses GPS rather than going silent. For most iPhone sailors a purpose-built app such as HoldFast covers this well, while chartplotter-integrated apps suit boats with NMEA instruments and cross-platform apps suit mixed iOS and Android crews.
A free anchor alarm can be perfectly adequate if it provides a genuine drag alarm and reliable foreground monitoring. The features usually worth paying for are true background GPS with the screen off, track history, and remote sharing. Avoid apps whose free tier is only a locked demo.
Both have a place. A chartplotter is always powered but you must be aboard and awake to hear it, and its alarm is often too quiet below. A phone app puts the alarm by your bunk and can be shared with crew ashore, but needs charge and a quality app. Many cruisers run both.