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Tides

Age of tide – springs, neaps and the delay after new and full moon

Is a given day at springs, mean or neaps? NauticTools2 answers this from the date, by the same rule as Table 4 of the German BSH tide tables. It also produces a yearly table with every day of a year and all moon phases.

• Springs
• Mean
• Neaps
• Age of tide
• Rule of BSH Table 4
• Yearly table

What does age of tide mean?

The tides are raised mainly by the moon, and the sun strengthens or weakens them. At new and full moon the sun, earth and moon lie in a line, their forces add up and the range is at its greatest: springs. At the two quarters they act across each other and the range is at its smallest: neaps. In between lie the mean tides.

The delay after new and full moon

The spring tide does not arrive on the very day of new or full moon. Water responds slowly, friction and the shape of the ocean basins hold back the tidal wave, and into marginal seas such as the North Sea it first has to run in from the Atlantic. So the greatest range follows the moon phase by some days. This interval is the age of tide, in German Springverspätung or Alter der Gezeit.

How large the age of tide is depends on the place. The German tide tables used to give it for each reference port. Today's BSH tide tables no longer do: Table 4 gives springs, mean and neaps uniformly, with the delay of the German Bight already included. That is why this tool has no reference port and no value to set. The result agrees with Table 4 day by day, checked against the 2027 table on all 365 days.

The Admiralty Tide Tables, by contrast, give each standard port its own age of tide. Tides ATT works with this value: on the tidal prediction form it appears in the line “Springs occur”, and the status springs, mean or neaps follows from it.

When do you need it?

• Tidal calculations: working with mean spring and neap curves needs the state. Tides BSH takes it over automatically.
• Passage planning: at springs the tidal streams run harder, high water is higher and low water lower.
• Drying out: if you take the ground at high water springs, you may not float off again for days.
• Shallow harbours and tidal flats: the yearly table shows at a glance which weeks are suitable.

The rule

1. Find the moon phase

   The times of the phases come from the calculation in Moon Phases.

2. Calendar day in CET

   The calendar day in CET (UTC+1) counts, as in the BSH tide tables. A full moon shortly before midnight UTC therefore already belongs to the next day.

3. Count four days

   Springs and neaps last four calendar days each, starting with the day of the moon phase. Their middle therefore lies about a day and a half after the phase, which matches the delay of the German Bight.

4. Mean

   All the days in between are mean tides.

Worked example

8 and 9 July are already mean tides. The first quarter on 10 July then starts the neaps from 10 to 13 July. The example of Scharhörn, Bake C under Tides BSH shows the same state.

What to watch out for

• The limits are not sharp: nature does not jump from one day to the next. The division is a working rule for choosing the curves.
• One rule for all places: by Table 4 the result applies uniformly. Outside the German Bight the true age of tide can differ.
• Not all springs are equal: how high a spring tide runs also depends on the moon's distance from the earth and the time of year. The rule does not distinguish this.
• Calendar day in CET: this applies in summer as well, the division does not follow summer time.

How it works in NauticTools2

1. Enter a date

   In the Age of Tide tile, enter a date and tap Calculate.

2. Read the result

   You see the state, the first and last day of the period and the moon phase that sets it off. Mean tides have no such phase.

3. Save and print

   Save and Load keep a date. The result can be printed as a report.

Yearly table to print

The Yearly Table button produces the whole overview for a chosen year: springs, mean and neaps for every day (as in Table 4) and all moon phases in UTC (as in Table 5). It is calculated and needs no printed tables. Handy for passage planning and for pinning up on board.

View the yearly table 2027 as a PDF ›

Frequently asked questions

Why can't I set an age of tide?

The BSH tide tables no longer give it for each place. Table 4 already includes the delay of the German Bight, and the tool follows the same rule. Tides ATT uses the value of each standard port.

Does the age of tide differ from place to place?

Yes. That is why the Admiralty Tide Tables give a value for each standard port. This tool follows the uniform rule of the German BSH tide tables.

Which years does the yearly table cover?

It is produced from the calculated moon phases, so it does not depend on a printed volume. It has been checked against Table 4 for 2027.

Not for navigation: all tidal values are approximations for training, exam preparation and passage planning. Wind and air pressure change the tide further. For navigation, the official tide tables are authoritative.

Related tools

• Moon Phases – new moon, full moon and the two quarters for a date
• Tides BSH – height of tide by the method of the German BSH tide tables
• Tides ATT – tidal predictions with standard and secondary ports