Tides and currents for sailors

Tide is not current

High water and slack are different events.

At many passes the current keeps running for an hour or more after high or low water. Use current predictions for timing, and tide heights for depth.

References 1

Flood, ebb and slack

Current builds from slack to a maximum and back.

The flood runs in, the ebb runs out. Slack is the turn, and it can be brief. Maxima differ through the day.

Slack windows at First Narrows, 6 October 2026. Real CHS predictions for one day. Plan the transit for a slack window, and know when the next maximum arrives.

Telltale Conditions in Current mode at First Narrows: five passes with the current rate now, the next slack and the next maximum for each. — In TelltaleCurrent at the passes, with the next slack. Switch Conditions to Current for the CHS prediction at First Narrows, Dodd Narrows, Gabriola, Porlier and Active Pass: the rate now, the next slack and the next maximum. Open the passes

In TelltaleCurrent at the passes, with the next slack. Switch Conditions to Current for the CHS prediction at First Narrows, Dodd Narrows, Gabriola, Porlier and Active Pass: the rate now, the next slack and the next maximum. Open the passes

References 2

Reading the predictions

Each station gives times and rates of slack and maximum flow.

CHS publishes them in the tables and through the IWLS service that Telltale reads. Rates are in knots; flood and ebb directions are given per station.

Use the station at your pass, not a nearby tide station.
Times are local; check daylight time.
Predictions don’t include wind or river flow.

References 1 3 2

Channels, points and back-eddies

Current is fastest in the middle of a channel and off points.

Behind a point the flow can reverse in a back-eddy. Close to shore you may find slack or even a fair current while the middle runs against you.

SOG, STW, set and drift

The current is the difference between where you point and where you go.

Set is the direction the water moves you; drift is its speed. With a calibrated log, compare STW and heading with SOG and COG to measure it. After a sail, Telltale works out what the current did on each leg for you.

The Forecast tab of a race session: HRDPS closest, the wind chart with the models ranked, and the current leg by leg as green and red bars in metres. — In TelltaleWhat the current did to your race. A session’s Forecast tab says, leg by leg, how many metres the current carried you or held you back, and which forecast model was closest along your track. Reviewing a sail

In TelltaleWhat the current did to your race. A session’s Forecast tab says, leg by leg, how many metres the current carried you or held you back, and which forecast model was closest along your track. Reviewing a sail

The Fraser River plume

The Fraser lays fresh water over the strait, moving on top of the tide.

At the mouth during freshet and a strong ebb, surface speeds of 3–5 kn are common; in the open strait, 1–2 kn without much wind. The edge of the plume often shows as a colour line.

References 4

Wind against current

Opposing wind and current shorten and steepen the waves.

A moderate breeze over a strong opposing current can build a short, breaking sea in a pass or at a river mouth. A pass that looks calm at slack can stand up an hour later as the current builds against the wind, so time those spots for slack or a fair current.

Picking a passage window

Combine current, wind and daylight.

Find slack or a fair current at each pass, check the wind for the same hour, and make sure you can still get there if you are an hour slow.

Passage planning

Sources and review

Official references checked on 2026-10-11. Product details and schedules change; the provider’s page is the current word.

Take it to the water

Check the stations before you leave, then record the sail for the debrief.

Open Conditions Record a sail