How to Read Tides: High Water, Low Water, Tide Level, and Current

Four things to separate on a tide table

Do not treat a tide table as only “what time the water comes in.” Before operating a boat or yacht, read these items separately.

Item	Why it matters
High-water and low-water time	Helps plan ramps, shallow water, docks, and return timing
Tide level	Shows the approximate water height at that time
Tidal range	Shows whether the day has large or small water-level changes
Current	Shows how strongly and in which direction the water may flow

Think through it like a conversation

“High tide is at 11. Does that mean 11 is the safest time?”

Not automatically. High tide means the water level is high. It is not always the same moment when current is weakest. Docking and undocking depend on current direction, wind, and the dock layout.

“If the tide level is high, is it easier to pass under a bridge?”

Think the other way. Higher water can reduce clearance between the water surface and the underside of a bridge. Bridge passage depends on local signs, official guidance, actual water level, and your vessel height.

“Can I use any nearby tide station?”

No. Tide conditions vary by location. Use the Korea Hydrographic and Oceanographic Agency’s smart tide forecast for the nearest practical station, and add separate river water-level checks where rivers, dams, or sluices matter.

How to use it before departure

1. Choose the tide station closest to the departure and return area.
2. Mark high water, low water, and tide levels for departure, arrival, and return.
3. Add extra margin around shallow water, ramps, bridges, and tidal flats.
4. Check wind, wave height, visibility, current, and fuel margin together.
5. If the timing is uncertain, delay departure.