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Hydrographic Institute shall not be liable for any failure or damage resulting from the use of this e-Service. Data published in this e-Service is unofficial and informative, and is not intended for navigational use. Official tidal predictions are available in annual publication entitled "Tide Tables – Adriatic Sea – East Coast". 

Methods of Prediction

All predicted times and heights of high and low waters are calculated from 7 major constituents using the harmonic method. Harmonic constants for the Standard Ports Rovinj, Bakar, Split and Dubrovnik are calculated based on continuous observations of the tide over a period of 18.6 years (Croatian vertical reference system for epoch 1971.5 – HVRS71). For the Standard Ports Mali Lošinj, Vis and Ploče harmonic constants are calculated based on continuous multiannual series of tide gauge registrations. Harmonic constants for the Standard Port Zadar are calculated based on continuous observations of the tide over a period of 18.6 years (2003.5 ± 9.3 years).

Times

All times of predictions are given in the Central European Time (CET = UTC + 1h). When Summer Time is being kept, one hour should be added to the predicted times.

Heights

All predicted heights are given in centimetres above Chart Datum. Chart Datum is understood to be the datum of soundings on the latest edition of a nautical chart edited by the Hydrographic Institute.

As in the area of the East Adriatic Coast tides are of mixed type with pronounced inequalities in height. Chart Datum is defined as geoid surface which is determined as Mean Lower Low Waters of Spring Tide on the tide gauges Dubrovnik, Split, Bakar, Rovinj and Koper in the epoch 1971.5, called "Hrvatski referentni sustav dubina mora za epohu 1971.5 - HRSDM71". Chart Datum is defined on the days of syzygy from the same series of tide records as the one used for the calculation of Mean Sea Level.

Meteorological Effects on Tides

Tidal predictions in these tables are computed for meteorological conditions without wind and a barometric pressure of 1013 hPa (1013 millibars). Changes in meteorological conditions will cause corresponding differences between the predicted and the actual tide. Variations in tidal heights are mainly caused by strong or prolonged winds and by unusually high or low barometric pressure. A low barometer will tend to raise sea level and high barometer will tend to depress it. Changes in level due to barometric pressure seldom exceed 30 cm but, when sea level is raised or lowered by strong winds this effect can be important.

The effect of wind on sea level is very variable and largely depends on the topography of the area, as well as on the wind direction, speed and duration. In general it can be said that in the area of the East Adriatic a strong wind blowing straight onshore will cause high waters to be higher than predicted, while winds blowing off the land will have the reverse effect.

 

Publication "Tide Tables - Adriatic Sea - East Coast"

Official poblication Tide Tables - Adriatic Sea - East Coast" are published annually. Tide Tables have been published since 1974. and are issued in Croatian and English.

General arrangement:

  • Diagram showing locations of ports (tide gauge stations) on the East Adriatic Coast is given on the inside front cover. The terms Standard Port and Secondary Port have no reference with their geographic position, size or importance.

  • Part I of these tables gives general data and harmonic constants for 8 Standard Ports with daily predictions of the times and heights of high and low waters in 2015.

  • Part II gives time and height differences and other constants which are used for prediction at 9 Secondary Ports on the East Adriatic Coast.

  • This volume also contains Phases of the Moon given at the end of the book, as well as the list of titles, symbols and abbreviations in Croatian and English.