As Seatruck operate from tidal ports, we thought it would help to try and explain just how this could affect your departure times.
Tides are the short-term periodic rise and fall of the Earth's oceans, created by the effect of gravity upon the Earth caused by the Moon, as well as the Sun.
In the UK we experience a semi-diurnal tidal regime, which means two nearly equal low and high tides each day. There are places in the world that will experience just one high and low tide a day (a diurnal tide); two uneven tides a day (a mixed tide); or even little or no tides at all.
As the Earth spins on its axis, the water in the seas closest to the moon are pulled by its gravity, which causes the first high tide of the day.
The second tidal bulge is caused on the opposite side of the Earth by the centrifugal force of the Earth spinning.
The Sun also creates a similar, smaller effect called the solar tide. The interaction of the lunar and solar tides causes spring and neap tides.
Spring tides occur around every full and new moon, when the sun, moon and earth are in line, or 'Syzygy'. These gravitational bodies align and reinforce each other, making the gravitational pull stronger, and therefore a bigger total tide.
For example at Liverpool, the spring tides are generally around midnight and midday.
Neap tides occur when the sun, earth and moon form a right angle, when the moon is in the first or third quarter.
…Still with me?
So why is my ferry departing late/early?
Well, back down to Earth, tides are also affected by the weather and geographical location.
Currents produced by tides are known as tidal streams. The moment that the tidal current ceases is called slack water which usually occurs near high water and low water, though there are locations where the moment of slack water differs from high and low water.
The shape of a river and the estuary can also affect the tidal pattern, producing long flood times and short ebb times. The time from high tide to high tide is roughly 12 hours 25 minutes, though low tide is not necessarily half way between them. It is possible for the flood tide to rise quickly after a period of low water lasting many hours (which can also be extremely dangerous).
Weather can also affect tides greatly and is almost impossible to predict. Strong winds blowing towards the port can have the effect of piling up the water, giving a higher than predicted tide.
So next time you book with Seatruck please bear in mind that your departure time may vary, depending on the tides.
You can always check the day prior to departure on our live online schedule available on the homepage here, and our Customer Service Team will always do their best to contact you to advise of any changes.
Or why not download the Seatruck App here to receive live updates and departure notifications.