Depth tells you whether you fit. Weather and tide tell you whether you should go at all. Helm puts both on the same chart you are navigating with, rather than in a separate app you check and then forget.
Predictions come from NOAA CO-OPS against the MLLW datum — the same reference the charts use. The live level feeds straight into the depth reading, so a number that looks fine at high water does not quietly mislead you three hours later.
Current arrows are drawn on the chart and rotate as you scrub through the day. You can see whether a pass will push you or hold you back before you commit to it, which matters more than wind for a slow boat in a narrow cut.
Animated wind, wave and current overlays sit on top of the chart rather than beside it, so you are reading conditions in the place you are actually planning.
A multi-day forecast in three-hour columns: wind and gusts, air temperature, rain, and water temperature where the data exists. Gusts are shown separately from sustained wind, because the difference is what decides whether the day is pleasant.
Outside US waters the forecast falls back to a global model, so the app still works — but the tide and current coverage is built around NOAA and is strongest in the United States.
Wave height and period get their own view. Height alone is a poor guide; a two-foot swell at a long period is a different day from two feet of short, steep chop.
The departure planner reads all of this and reduces it to one bar: when the passage is calm and when it is not. That is usually the only question you actually have.
NOAA CO-OPS, against the MLLW datum, the same reference used by the charts.
Yes, tide predictions are computed locally. Live weather and AIS need a connection.
Weather falls back to a global model. Charts, tides and currents are built around NOAA and are strongest in US waters.
Helm Boating