Predicting Tidal Currents' Timing and Velocity

In a previous post, I mentioned Capt'n Jack's Tide and Current Almanac and discussed the Rule of Thirds. What I failed to mention at the time, is how to determine tidal currents' velocity and direction. 

Tidal Currents in Dana Passage

Fortunately, it's not that difficult. You do need to have two pieces of information: a reference tidal station (one of six NOAA stations)  for tidal currents and the corrections for the body of water you are interested in.

In the South Sound, our reference tidal station is the Tacoma Narrows. By checking the reference station, you will see: times of maximum ebb (outgoing current) and maximum flood (returning tide) with the current speed of each in knots, as well as the time of slack (relatively calm water) between them. This will be repeated throughout the day. 

To determine the tidal currents for the body of water you are interested in, you need to find its corrections. These are in the back of the Capt'n Jack's Almanac as well as on SeaTrails charts (pictured to the left). After you locate the body of the water you are interested in, use simple arithmetic to add or subtract time to the max flood, the max ebb, and slack times between. Use the multiplier to factor the maximum flood and ebb. 

Once you figure out what the tidal currents are, you can apply them to the Rule of Thirds to get a really accurate picture of what the tidal currents will be doing on that day.