The ability to identify where eddies and eddy lines might form when looking at a nautical chart, and how to spot them on the water (reading the water), are important skills for a sea kayaker.
A bit of basic knowledge can help you avoid dangerous areas or plan trips through them, either at times where currents are at their slowest or to use the back eddies to your advantage.
What are eddy lines and eddies?
An eddy is a section of circular current that tends to flow in the opposite direction from the main river current. These generally form off land that juts out into the water. Current flowing around one side of the headland will create an eddy – current running the OPPOSITE direction – on the other side.
The eddy line is the point at which the opposing currents meet.
The stronger the current flow and the further the headland pushes out into the flow, the more defined and visible the eddy line. The more distance between the shore and the headland on the down current side, the larger the eddy.
These eddies are useful for paddling against the current. Large ones provide a safe bailout point to get out of stronger current. We’ll use these as a staging area for play or taking a break.
This video was taken toward the end of an ebb off Fort Flagler State Park in WA. You can see how the current is running to the right in the main channel, but just off the edge of the shore it’s moving to the left. Where it spins back left is the point where the eddy line starts.
In the conditions shown, there is minimal current and it will do nothing more than turn your kayak or SUP. It’s small, so there is no real bailout point, but it provides a great view of what to look for when paddling.