Wind against current and tide rips
Sea state · Power & sail
When wind or swell runs against a strong tidal current, waves get shorter, steeper and quicker to break. Plan passes, straits and bars for slack water or a fair current using current predictions, not tide times.
Safety first
- Strong eddies near narrows can swing the boat suddenly. Keep good steerage speed and be ready at the helm.
- At full flow some passes run faster than many displacement boats can motor; the Coast Pilot notes Deception Pass can be prohibitive to some craft except at slack.
- An engine failure in a tide rip is serious. Make sure fuel, filters and cooling are in good order before a pass; for sailboats in these waters the Coast Pilot calls a reliable engine an absolute necessity.
Why it happens
- A current running against the waves shortens them and makes them taller, so they are steeper, closer together and break sooner. When the current runs the same way as the waves, they lengthen and ease.
- Tide rips form where fast currents meet points, banks and shoals, sometimes with little wind at all. Add wind or swell against the current and they can become dangerous to small craft.
Pacific Northwest examples
- Strait of Juan de Fuca: the ebb runs strongest along the south shore, and with wind and swell against it a short, choppy sea builds near the entrance. NOAA's Coast Pilot lists heavy rips off Cape Flattery, Race Rocks, Dungeness Spit and Point Wilson.
- Deception Pass: the current in the narrows sometimes runs faster than 8 kt with strong eddies, and westerly weather can raise swell and rips that make it dangerous to all small craft. The Coast Pilot advises going through at slack.
- San Juan Islands and nearby passages: currents are strong in places with heavy rips. The Coast Pilot warns sailing craft not to try them against the current unless the wind is fair and fresh, and calls a reliable engine essential.
- Coastal bars: the NWS Columbia River Bar forecast lists ebb times and speeds because an ebb running out against incoming swell is when a bar is at its worst (see Crossing a bar).
Timing a passage
- Use tidal current predictions for the actual pass (NOAA Tides and Currents), not tide heights. NOAA says the common assumption that slack water comes at high and low tide does not hold for most locations.
- Aim to arrive at slack or with a fair current, and plan the earlier legs so you get there on time. If you are early, wait somewhere safe rather than push through a strong opposing current.
- Slack in a narrow pass can last only a few minutes, so plan to be at the entrance as it begins.
- Check the wind forecast for the hour you will be there. Westerly wind and swell against the ebb in the Strait is exactly the combination the Coast Pilot warns about.
Sources (6)
nauticalcharts.noaa.gov · higherlogicdownload.s3.amazonaws.com · tidesandcurrents.noaa.gov · oceanservice.noaa.gov · forecast.weather.gov · weather.gov
General guidance for recreational boaters, researched from the sources listed and written in our own words. Your equipment manuals, local knowledge, the Navigation Rules and a qualified instructor come first.