When the Tide Is Right

Whereas tide charts note the vertical rise and fall of water, tidal current charts describe the horizontal flow of water with respect to the rise and fall of tides. I can’t overstress the importance of understanding how to read and predict tidal currents.

In a previous post, I discussed the Rule of Thirds and how to calculate currents' velocities. Once you have a better understanding and representation of the tidal currents' speeds and times for a given area, you have an improved understanding of what to expect...

Tidal 'River' in British Columbia

Tidal rips are disturbances in the water’s surface (and deeper) and make take the form of fast moving water, whirlpools, standing waves, and uneven surfaces. Though few tidal rips in the Puget Sound region are extreme (Deception Pass is an exception), other places in the world, including passages within British Columbia, have some very dangerous tidal rivers of water.

Tidal Rips in Dana Passage

There are many underwater causes for tidal rips and it is often the underwater terrain, or bathymetry, that determines the flow and movement of tidal currents. Underwater channels often allow a large amount of water to move quickly, often more quickly than the surrounding water, creating the appearance of a river of water. When flooding tidal currents reach underwater shelves or walls they often rise upwards, causing upwelling on the surface. These shelves can also create the appearance of currents as rollers as they become more pronounced when reaching shallower water. When a river or inlet meets another, they often create a clashing system, particularly when one current flows over another’s underwater channel. When several inlets converge in a single meeting place strange and unpredictable things tend to occur.

Sailboat Traveling in Eddy at Deception Pass

Eddy lines can occur near the edge of a tidal rip. They are often seen as water movement contrary to the tidal flow. Eddies are protected areas, often near the shoreline, that allow one to travel against the current’s flow. They are always unidirectional, in that they appear only during either a flood or ebb event, and often appear behind points or outcroppings on the shoreline. Eddies are very helpful when paddling against an opposing tidal current.

If the water's surface is smooth and you aren't quite sure which way the current is moving, easy ways to identify current directions include watching debris floating on the water or peering below the surface to observe the direction of bent and waving vegetation.

Tidal rips typically last until the next slack tide. Slack tides vary in duration, and their duration is often inversely related to the increasing speed of the currents before and after them. So the stronger the tidal current, the shorter the slack time. Stronger currents are typical during spring tides, which are associated with days surrounding new and full moons.

To negotiate rip currents, you must first always consider your ability level. If you question your ability to traverse or run a tidal rip, wait, in time the tidal current will diminish for safer travel. Other tips include staying upright on your board with soft knees and keeping a rapid, almost explosive, but controlled shortened paddle stroke. Be prepared to experience things you might not normally feel on the water, like a rip grabbing your fin and starting to spin you round. Another surprise is paddling through a period of rough, whitewater conditions and then reaching a flat, almost bulging, calm section of upwelling. Or finding that you have to paddle extremely hard to cover 25 feet.

Like so many things, controlled exposure to different tidal currents will help you build your confidence and experience with them.