We help prepare a passage decision, not issue a clearance to depart. The public tool combines a working document with a limited comparison of traceable weather-model runs. Personalised forecasts with AI-assisted analysis and expert review are in closed testing; an automatic report does not imply human review.
Three clocks, three different claims
- Editorial review: when we reviewed a source entry or article. This is not weather freshness.
- Issue / model initialization: when the issuer produced a bulletin or initialized a run. Forecast valid time is separate; provider ingestion and download time are separate again.
- Valid interval: the hours and geographic zone to which a statement applies. Match these to leg ETAs, not just departure.
How an automatic comparison must work
- Use a skipper-supplied, navigationally checked waypoint track and explicit planned speed. Two ports are insufficient: a straight line may cross land. The service must not silently manufacture a route.
- Sample positions and passage times along each leg; retain the requested point and actual model grid point. Planned ETAs do not account for sailing polars or current unless those calculations are implemented and validated.
- Compare wind, gusts and significant wave height to user-selected limits. Wave period, direction, swell, tide, visibility, thunderstorms and escape options remain separate checks; no universal yacht-length-to-safe-wave rule.
- Compare like-for-like values at the same valid time and position. A deterministic-model range is not an ensemble probability, independence test or probability of safety.
- Mark missing, stale or untraceable data as incomplete; do not award a positive score or rank an incomplete departure as preferred.
- AI may explain validated structured results. It must not invent numbers, forecast updates, shelter, warning status or an expert endorsement.
Provenance for every number
Keep provider, model ID, available model version, exact run time (or explicitly unknown), valid time, variable, units, grid coordinates, retrieval UTC, response hash and calculation version. A latest-run metadata endpoint alone does not prove that a particular timeseries came from that run. Preserve unknown values as unknown.
Free data is not a free commercial API
Open-Meteo distinguishes non-commercial free access from commercial API use. Its marine documentation cautions against using coastal current data for navigation. ECMWF open data requires attribution; delivery and infrastructure still have costs. Verify each provider’s licence before changing the site’s business model.
Closed-test access and public-tool limits
Personalised AI-and-expert forecasts are in closed testing; public payments, automatic delivery and self-service expert booking are not open. The public comparison can retrieve available regional warnings and nearby observations; optional current forecasts require separate consent. Regional warnings are not a verified intersection of warning zones with your route. Depths and navigability are not checked, gust products are not yet comparable, and the current model is not suitable for tidal gates or harbour navigation. AI explains validated results, not predicts weather or certifies safety. Expert review must identify the specialist, scope, turnaround, privacy and cancellation terms.
Report and correct
Area pages link to a private editorial correction form. It records the site page and your note, not a passage submission. Do not include personal information. A link responding with HTTP 200 is only a technical check, not proof of a valid forecast.
Methodology and product status reviewed: 27 September 2026. The skipper remains responsible for the voyage and final interpretation of weather information.
A complete claim has evidence and a boundary
For each decision-relevant statement identify its evidence type: official bulletin, observation, model field, user assumption or editorial explanation. Retain UTC, variable definition, geographic scope and missing information. A local observation may challenge a forecast at that place and time without validating tomorrow’s landfall. Numerical model agreement must not be relabelled as a calibrated safety probability.
- ECMWF: forecast uncertainty — Ensemble uncertainty; not a yacht-specific safety probability.
AI editorial roles are not expert biographies
We use general marine-weather review and regional AI review roles for the Mediterranean/Indian Ocean/Asia, Atlantic/northern/high-latitude waters, and Americas/Pacific. They check geography, source selection, evidence limits and practical passage questions. AI has no personal sea miles or professional licence. Human meteorologist review is stated only when an identifiable specialist has actually reviewed the particular report.
Editorial review of this material: 27 September 2026. This date concerns the page content; check current forecast issue times and validity at the original sources.