The Channel

The shortest distance across the Channel is from Shakespeare Beach, Dover, to Cap Gris Nez (the headland halfway between Calais and Boulogne). This distance is 18.2 nautical miles which is approximately 21 land miles. There are 2,000 yards or 1852 mtrs to a nautical mile. Most of the England/France swims start from Shakespeare Beach between one hour before high water and one hour after high water, although the pilots do start at other times and places, depending on the tide, the weather conditions, and the swimmer's ability. France/England swims (when these are permitted by the French authorities) usually start from Cap Gris Nez or its immediate vicinity. The traditional start time is about 3 to 4 hours before high water, although this can also vary considerably depending on the tide, weather, swimmer and pilot. With the use of computerised plotting for course calculations and the modern electronics on the pilot boats, start times and places can be evaluated before the swimmer enters the water, and the best choice of route made.

The FLOOD TIDE flows from the South West from 1.5 hours before HIGH WATER to 4 hours after HIGH WATER DOVER. The EBB TIDE flows from the North East from 4.5 hours after HIGH WATER to 2 hours before HIGH WATER DOVER. As the tidal cycle is a little over 12 hours from one high water to next, the times of high water change every day getting later as the days progress.

Because of this movement of water from one place to another, the Dover Straits are prone to strong tidal flows, and a large rise and fall in water between high and low tide. To complicate things a little more, the position of the moon relative to the earth and the sun affects the gravitational pull that is moving the water. When the sun, moon and earth are in line we have maximum tides known as SPRING TIDES. This is every 14 days on the new moon or the full moon. When the moon is at 90° to the earth, we have minimum tides known as NEAP TIDES. This is every 14 days when the moon is in its first and third quarter. Thus we have 14 day cycles with the tides going from Springs to Neaps and back to Springs. From tidal atlases and nautical almanacs we find that at Dover: Mean High Water Springs is 6.7 metres. Mean High Water Neaps is 5.3 metres. For Channel swimming - Spring tides are 6 metres or more and Neap tides are 6 metres or less. Most swims take place on the Neap tides. These are the slacker tides and show as a more direct line on the chart. The lower the tide, the longer the period of slack water when the tide turns, and the slower the tidal flow. Approximately 6am and 6pm (GMT).

Water temperature.

This is between 57°F and 64.5°F (14°C to 18°C). The temperature is around 57 to 60°F at the end of June beginning of July, then rises slowly to 64/65°F by the end of August, then it usually drops by a couple of degrees before the beginning of October. There are however exceptional years like 1995 when the water temperature reaches 67°F (19°C).

Air temperature and chill factor.

This varies considerably depending on the weather and the hours of daylight. The longest day is about the 21st of June, giving daylight from about 0330 to 2200 hours. This decreases to 0600 to 1900 hours by the end of September. Body heat is lost from the parts of the swimmer exposed to the air (head and shoulders, etc.). The air temperature is higher during daylight hours, therefore the longer the day, the greater the period of higher air temperature, and the smaller the loss of body heat.

The English Channel is one of the busiest shipping lanes in the world, with approximately 600 vessels moving up and down them every day, and ferries, hovercraft, seacats and jetfoils crossing between England and France at very regular intervals. Because of this international shipping lanes have been agreed and their areas marked on the charts. On the English side we have the South West Lane which is for vessels travelling down Channel to the Atlantic. On the French side we have the North East Lane for vessels which are travelling up the North Sea areas. Crossing from Dover there is the English inshore traffic zone which is about 5 nautical miles wide, followed by the South West Lane which is approximately 4 nautical miles wide. In the middle is an areas known as the Separation Zone which is one nautical mile wide. Then there is the North East Lane which is approximately 5 nautical miles wide, followed by the French inshore traffic zone which is 3 nautical miles+ (depending on where you are) to the French beaches. The English Coastguard, stationed at Langdon Battery Dover, and the French Coastguard, stationed at Cap Gris Nez, keep radar and VHF watch on the whole of this area liaising with the vessels using the Channel. They broadcast navigational bulletins every half hour and log vessels using the lanes to co-ordinate the movements and monitor safety. Channel swims differ from other swims of this distance by their complexity and the localenvironment. This is why it is one of the ultimate challenges.