Tides & Timetables
Our ferries travel to places with some of the greatest differences between low and high tide in the world. This affects how we schedule our sailings. You can find out more below.
Why don't Condor Ferries sail on the same time each day?
The short answer is because of the tides and the depth of water at low tide in some of the ports we serve.
At first glance, the way in which our sailing times change on an almost daily basis across the course of a month might seem strange. We know that our passengers would prefer sailings on our network of routes to depart at the same time each day varying according to changing customer needs at different times of the year - if at all. Dig a bit deeper and you will find that there is one overriding reason why our departure times from all ports vary across the month drifting backwards and forwards - the tide.
Tidal ranges in the Channel Islands and Baie de St Malo are amongst the highest in the world and at certain times of the month the tide goes out by up to 40 ft or almost 12 metres - that's about the height of a two storey house. As the tide goes out this means 40ft of water disappears as the tide retreats and the beach or coastline extends hundreds of feet further from the land than at high tide. This characteristic of Jersey, Guernsey and the St Malo region is part of their astonishing beauty, but it does create some challenges for the mariner. It means that the amount of water in the ports of Jersey, Guernsey and St Malo under the ships’ hull can also vary by the same amount and at some times of the month, a port, like Jersey does not have enough water to allow the ships to berth.You may notice that the linkspan which vehicles use to embark will sometimes be level and others, slope downwards because of a change in the tide, as the pictures above show.
How often do the tides change?
It varies, again by location. However, in general in the Channel Islands there are two low and two high tides a day. The times of these shift each day and the more the tide has to go out or come in, the longer this may take and the faster the tidal stream will flow. Tidal stream is a phrase used commonly to describe the current created by the flow of a tide in or out. The best known example on our routes is the Race of Alderney.
What about Spring Tides?
The first thing you need to know about Spring tides is that they are not confined to the Spring season, but happen all year round. Each month, the amount by which tides rise at high tide and drop at low tide changes with the phases of the moon. A spring tide will occur around twice each Lunar month (roughly the same length as a conventional calendar month) and it causes the biggest difference between high and low tides. The opposite kind of tide is known as a Neap tide - which also occurs twice a month - where the tide goes in and out by the least amount. Some people abbreviate these to Springs and Neaps.
How does the tide affect Condor Ferries Fast Ferry schedules?
The first and most important of these challenges is that even our fast ferries which have a draught of about 3.5m or abut 13ft cannot always berth in Jersey as the port "closes" for up to four and a half hours per day during the Spring tides as the commercial port does not have sufficiently deep water to allow the ships to enter the harbour and berth safely.
St Malo, which has the same big tidal ranges can also be affected by the same problem though less often. Guernsey, which also has the same tidal ranges is fortunate in that St Peter Port has deep water and it is possible for our ships to berth in almost all states of the tide all year round.
Unfortunately, the tidal restrictions in Jersey Harbour mean that during some Spring tides, as well as shifting our scheduled sailing times, we have no option but to schedule several ferries one after another or at the same time to make the most of the port opening hours so that we can maintain the regular service.
Our UK ports, where tidal ranges are less dramatic, are not affected by tidal closures.
What about Commodore Clipper and Commodore Goodwill?
Both conventional ferries draw around 6m and their schedule is carefully timed to avoid the periods when the tides are predicted to be low in Jersey.
How reliable are tide tables?
All tide tables, not just those in the Channel Islands are predictions not absolute – in some ways like a weather forecast. The range by which the tide actually varies on any given day can be affected by a number of other factors which cannot be foreseen when we are developing our schedules. These include
- the atmospheric pressure (the higher the pressure the more it "pushes" down on the water and the tide drop may be more than predicted),
- the wind direction and force ( a wind can "push" the sea in to the shore creating a higher tide than predicted or further out creating a lower than expected tide).
When planning our schedules we use the tidal predictions and allow an extra margin of time with the aim that the overall service can be maintained.