NOAA CO-OPS station 9063079 provides measured water-level information near Marblehead. Confirm the observation time, units and selected datum before comparing a value with a chart or previous trip.
Charted depths reference a low-water datum, while a station display may offer several datum choices. Values from different reference surfaces cannot be compared directly.
Use the station as one planning input. Actual clearance and depth also depend on sounding accuracy, vessel draft, squat, waves and local bottom change.