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Secondary Port Tide Calculation Worksheet
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The Secondary Port Tide Calculation Worksheet provides a structured method for converting tidal predictions from a standard port into accurate tidal times and heights for a secondary port. The worksheet uses known relationships between the two ports, including time differences, tide ranges, mean sea level (MSL), and chart datum corrections to derive local tidal predictions.
Purpose of the Worksheet
Secondary ports often do not have complete daily tide tables published. Instead, mariners use data from a nearby standard port and apply corrections to determine:
- High Water (HW) times and heights
- Low Water (LW) times and heights
- Local tidal conditions at the secondary port
The worksheet provides separate procedures for:
- Semi-diurnal tides (two high waters and two low waters each day)
- Diurnal tides (A tide with only one high water and one low water occurring during a tidal day. Also known as single day tide.)