Plan your passage.

NOAA tidal-current predictions, not tide-height predictions. Wind, weather, river discharge, waves and actual speed changes are not modeled. This is a passage estimate, not a navigation chart or a verified safe route. Check charted depths, shoals and channel restrictions before navigating.

Routes are approximate passage-planning courses, not verified charted tracks. The continuous course starts at the C&D entrance and runs down Delaware Bay, through Cape May Canal, offshore along New Jersey, through New York Harbor and Long Island Sound, north of Block Island, through Vineyard Sound north of Martha’s Vineyard, and into Nantucket Harbor’s entrance. Select either direction by swapping start and finish. Artificial Island uses Baker Range Channel (DEB2111) because NOAA retired ACT4256 in 2023.

The New York course follows the harbor and East River with bends around islands. Course waypoints are separate from prediction stations. Station positions are projected onto the appropriate course and their current vectors are interpolated along it. The Sound course follows a straighter offshore corridor past Execution Rocks and Eatons Neck. It passes southeast of Hart Island and south of Fishers Island before continuing north of Block Island and Martha’s Vineyard. Nantucket ends at the harbor entrance, not at a dock. The nautical basemap is NOAA’s chart display, including charted depths and navigation marks at appropriate zoom levels. It loads from NOAA separately from the saved current predictions. The Simple coastline view uses saved NOAA land polygons. Scroll the mouse wheel over the map to zoom in and out. Selectable waypoints are main passage endpoints; intermediate channel bends remain in the route without extra markers or arrival rows. Map marks are visual references; start and finish selection uses the named course waypoints.

Bay Shore and False Egg Island use sine/cosine interpolation between NOAA maximum-current and slack events. Harmonic stations use six-minute predictions. Subordinate stations in the eastern sounds also interpolate between maximum and slack events. Current vectors are interpolated spatially between adjacent stations at the same time. New Jersey offshore legs have no supported offshore tidal-current correction and use boat speed through water; gray segments mean unmodeled current, not slack. A midpoint integrator advances the boat in steps of at most one minute. The boat compensates for cross-current to stay on the route; along-course speed is √(boat speed² − cross-current²) + following current. Passages with insufficient forward progress are excluded.

Best and worst mean shortest and longest completed passage among departures at 10-minute intervals within ±10 hours of the last calculated departure. The search includes both endpoints and can cross midnight; choosing a result keeps the comparison window fixed until Calculate passage is pressed again. Daylight saving is applied. A rolling cache keeps 57 weekly blocks: four previous weeks, 52 weeks of departure dates, and one arrival buffer week. A weekly refresh downloads the new week and removes expired blocks after successful download. Passages are limited to 120 hours.

NOAA station list · NOAA prediction API · Station changes