Understanding tides when passage planning
When planning a trip in tidal waters, check the tides before going afloat. Use almanacs, charts, tide tables and tidal stream atlases to gather all the data you need.
It is advisable to have a written note of tidal data for your trip including:
Your boat’s draft.
The predicted times (in Universal Time) of high and low water.
The heights of the tide.
The tidal ranges.
The direction and speeds of the tidal streams en route.
Check when and how the state of the tide will affect local areas including shallows, harbour entrances, sand bars, headlands and estuaries.
Check predictions and forecasts to determine if and when rough seas caused by wind against tide will occur. Be prepared to change your plan to avoid being caught in adverse conditions.
Use all the data you gather to:
Plan your departure time(s).
Take advantage of tidal flow to shorten journey time.
Estimate your journey time.
Plan your arrival time(s).
Avoid potential hazards caused by tidal conditions.
Ensure there will be safe clearance under your keel at all times.
Double check all calculations.
Remember to allow for Summer Time, if applicable.
Avoid shallow water on a falling tide.