Know what each layer means.

PassageBuoys combines public source products with application-generated visualizations. Their locations, timestamps, units, and limitations matter.

NOAA NDBC observations

Public National Data Buoy Center station catalogs, latest observations, and realtime history provide wind, combined wave height, dominant period, and mean wave direction where reported. Different stations have different sensors. A map marker does not establish that a station has a recent wave observation or that its conditions apply to a nearby vessel.

Swell and wind sea

NDBC spectral summaries supply separated swell and wind-sea values where available. These are reported separately from combined seas. Missing separation is not inferred from mean wave direction. Bearings identify where waves or wind come FROM; colored arrowheads show travel TO. Source ages can differ between meteorological and spectral reports.

NOAA Ocean Prediction Center charts

Embedded images are NOAA source products with their own printed units and issue/valid times. Availability varies by basin, product, and lead. Check the original NOAA product and its valid time. A retrieval timestamp or HTTP file-modification time is not necessarily the forecast’s issuance time.

Tidal-current predictions

NOAA CO-OPS values are harmonic station predictions for a specified bin, not a live measured current field. The app’s current layer uses bin 1. Descriptive along-line components compare predicted set with a reference leg; they do not interpolate current between sites or provide instructions about vessel operation.

Maps and reference geometry

Map tiles are © OpenStreetMap contributors, subject to OpenStreetMap attribution and licensing information. Reference geometry uses public-domain Natural Earth data distributed through world-atlas. The calculation checks that dataset’s coastline but does not establish depth, navigability, small-hazard clearance, channel access, legal restrictions, bridge clearance, or traffic separation. Offshore offsets are approximate, and displayed harbor approaches are exempt from the cruise offset.

History and application-generated interpretation

Trends summarize observed history without extrapolating future weather. Descriptive sea-state relationships and differences between stations are calculated by the app. They are not official NOAA advice, navigational recommendations, or an evaluation of a vessel or crew. Source ages and gaps remain important; sample values are labeled and are not live observations.

Original sources and independence

Consult the NOAA National Data Buoy Center, NOAA Ocean Prediction Center, NOAA Tides and Currents, and official NOAA marine forecasts and warnings.

PassageBuoys is not affiliated with, certified by, or endorsed by NOAA, the National Weather Service, the U.S. government, OpenStreetMap, or other providers. See the Weather Disclaimer, Terms of Service, and Privacy Policy.