Privacy Policy — Rhumb Logbook
Effective: 22 October 2026
Summary
Rhumb Logbook requires no account and has no analytics or trackers. Your positions and your logbook stay on your phone and, if you choose, in your own iCloud or Google backup. We never receive them.
Location in the background
The app's purpose is to log your passages at sea without you starting or stopping anything. To notice that you have left harbour, it needs location access all the time, including while the app is closed or not in use. In harbour it waits for the phone's low-power location updates and asks for a position only when the phone reports that you have moved a few hundred metres. It then checks for a few minutes whether you are moving on water. If you are, it records a GPS position every few minutes until you tie up. If you are not, it stops using GPS until the next move. On Android a notification is shown whenever the app is checking for a passage or logging one.
Every position is processed on the phone: the sea map that tells water from land is stored on the phone, and the distances, night hours and days are computed there. You can turn location off for the app at any time in the phone's settings; the app then logs nothing until you turn it on again.
Your logbook
Passages, their tracks, your boats, your saved places and your paper-logbook totals are stored on the phone. On iPhone they can also sync to your own iCloud account, and on Android they are included in the Android backup to your own Google account when that backup is on. We cannot read either. Deleting the app, or the app's data in the phone's settings, removes the logbook from the phone; your own iCloud or Google backup is yours to keep or delete.
What leaves your phone
No position and no logbook data is sent to us or to anyone else. The app makes two kinds of network request:
- The sea map is downloaded once from a public release server (
github.com), and again only when you choose to install a newer map. - Chart tiles for the passage map load from Rhumb's own servers (
tiles.rhumbapp.com,tile-assets.rhumbapp.com) and from OpenSeaMap's tile server. These servers see your IP address and a Rhumb user agent, like any web request, and the tile coordinates needed to draw the map.
Exports you make (PDF, CSV, GPX) and diagnostics you share go only where you send them.
Purchases
Logbook Unlimited is bought through Apple's App Store or Google Play. The store processes the payment under its own privacy policy; we receive no payment details and no identity data. The app only remembers on the phone that the purchase was made.
Changes
If this policy changes, the new version will be posted at this address with an updated date.
Contact
Questions about this policy: [email protected].