A common question from Sea Kayakers new to Clayoquot Sound revolves around the tidal currents. In many locations around British Columbia there are detailed current speed and time predictions published to assist mariners in route planning; no such predictions are published for Clayoquot Sound. Instead we rely on the Tofino Tidal Predictions published by the Canadian Hydrographic Service.
When paddling in more inland waterways (such as the Gulf Islands, San Juan Islands, Desolation Sound, Broughton Archipelago) mariners need to pay very close attention to Current Speed / Turn times vs Tidal High/Low Times. In inland waterways the time difference between the tide high-or-low and current slack water can often have hours long differences.
When the tides are rising, the current will move flood from the open ocean towards the inlets. When the tides are falling, the current will ebb from the inlets towards the open ocean. Examining the bathymetry lines (the shape of the sea floor) on a nautical chart, one can easily see the deep channels scoured by the currents. As in a river, the fastest current can be expected in the middle of those channels, while the most turbulent areas will be located along the edges.
Tidal currents experienced in Clayoquot Sound will be directly proportional to the size of the tidal range experienced. For instance on a day with a 4 foot difference between and high and low tide one should expect much slower current speeds than a day where we experience a 10 foot range between high and low tides. For reference, the largest tidal ranges we experience in Tofino are about 13 feet (4 meters).
Significant changes to barometric pressure (low-pressure from a storm, or high pressure during fair weather) can alter the tidal heights. A strong winter storm will lower the barometric pressure and result in larger tides. Conversely a strong ridge of high pressure will decrease the tidal range. A general rule of thumb; a change of 1 mb of pressure results in a 1 cm change in sea level. Tidal predictions are based on the average air pressure of 1013 mb. Therefore a strong high pressure system of 1033 will lower tidal heights by 20 cm. A low-pressure system of 980 will increase tidal heights by 33 cm. Pay attention to fast changes to weather systems.
For the most part the currents manifest themselves as a gentle river moving up and down the passages. Eddy lines can be expected at headlands but once within most current channels the only reminder of the current will be the effect it has on your speed. Understanding how to ‘Ferry’ across the current is an important skill, both while crossing small passages in the inner islands, and larger crossings on the outer coast. On Long crossings, a strong flood or ebb tide can significantly alter your course.
Please don’t mistake the lack of published current predictions as a sign the currents should be ignored. The currents can significantly influence the sea-state experienced in Clayoquot Sound.
On calm days with a large tidal range, the currents themselves can create hazards. There are locations we can experience up to 5 knots of current which can generate a standing wave big enough to surf. Many kayakers have run into difficulty by not appreciating the speed of the currents within some channels. Many, but not all, of these locations are indicated on the Marine Chart by current directional arrows.
On windy days, the current will play an important role. Within the inner waters, the current can drastically change the waves experienced. The waters directly in the Tofino Harbour are a great example. It is very common to experience a North Westerly wind in the afternoon during the summer months. During a rising tide with a flood current, the wind and current will be moving in the same direction; causing the waves to be elongated and less rough. However with a falling tide / ebb current the wind waves will be accentuated and much rougher conditions can be expected.
Perhaps the largest consideration with currents in Clayoquot Sound is the influence it can have on the incoming open ocean swell. An outgoing ebb current, will shorten the wave length of incoming ocean swell making the waves much steeper and closer together. Couple this with wind waves, and hazardous conditions can occur on the outer coast. A few locations of note include Moser Pt. by Vargas Island, the Gerrard Group by Flores Island, and Sharp Pt by Hot Springs Cove.
Regardless of where you paddle a healthy respect for the tides and currents will serve you well.