Privacy Policy
Last updated: 13 September 2026
The short version
Predict Sea is built for sailors on slow connections, and that shaped a simple privacy posture: we don't collect, store, or transmit any personal data.
No accounts, no tracking
- There is no sign-up, login, or user profile.
- We use no analytics, advertising networks, tracking pixels, or fingerprinting.
- We set no cookies.
- All page assets are served from this site — no third-party requests are made
from your browser while you use the app, with one opt-in exception below. The
buoy observations and storm-track overlays are first-party files too
(
data/obs/ndbc.json,data/storms.json, written by our own pipeline), so switching them on contacts no other server.
Optional overlay that contacts another server
The Seamarks overlay is off by default and only loads when you switch it on: it fetches map tiles from tiles.openseamap.org (OpenSeaMap). While it is on, that provider receives the standard technical details of an image request (your IP address, the map area you are viewing). We send nothing else, and switching the overlay off stops the requests. The overlay stays on for the rest of the browser session only; a later visit starts with it off unless you switch it on again.
Sponsors
Predict Sea may show a small number of clearly labelled sponsor slots
(see the Sponsors page). These are static files served from
this site — a short list (sponsors.json) and, at most, a small logo hosted
here. No sponsor code runs in your browser, nothing is loaded from a sponsor's
servers, and we count neither views nor clicks. Which sponsor you see depends
only on the calendar day, never on you. If you follow a sponsor link you leave this site
and that site's own privacy policy applies; the link is marked rel="sponsored"
so browsers and search engines treat it as such.
What stays on your device
- Preferences (such as the Data Saver switch) are kept in your browser's local storage. They never leave your device.
- Saved and recent spots: positions you star in a point forecast, and the last few positions you tapped on the map, are stored only in your browser's local storage so the search box can offer them again. Nothing is uploaded. Starred and recent spots, and any imported positions, are kept in this browser's local storage and are readable by anyone who uses the same browser profile.
- Your location: the "use my location" button asks your browser for your position once, only when you press it, and uses it solely to centre the map and open a point forecast for that moment. The GPS fix is never written to local storage — it is not added to your recent or saved spots — and it is never transmitted anywhere. Your position is used once to centre the map and open the table and is not stored; the browser may reuse a fix up to 5 minutes old. It is not placed in the page address either, so it is not in your browser history and a reload does not bring it back. Only if you press Link or Share in that panel is the position written into the link you copy or share. Close the panel and it is gone.
- Watch-list notifications: browser notifications are optional and only requested from the watch-list board, never elsewhere; alerts are computed in your browser from the last model run seen and fire only while the tab is open — nothing is sent to a server and no push service is involved.
- Settings export / import moves your saved spots and preferences as a file you keep: the export file contains your saved spots and preferences and is written only where you choose to save it; nothing is uploaded.
- Offline cache: a service worker stores recently viewed forecast data on your device so charts keep working without connectivity. You can clear it at any time via your browser's site-data settings.
Server logs
Like virtually every website, our hosting provider may keep standard technical logs (IP address, requested file, timestamp) for security and capacity purposes. We do not use these logs to identify or profile visitors, and they are not shared with sponsors or anyone else.
Contact
Questions about this policy? Contact 19 Lat via the address on our Terms & Data Sources page.