Straits of Gibraltar
Water temperature: The temperature of the water in the Straits of Gibraltar may vary between 15ºC in winter to 22ºC in summer, so it is advisable to attempt the crossing in the spring or summer period when the risk of hypothermia is smaller. The duration of the crossing depends on the characteristics of each swimmer and the sea and current conditions but it is estimated to be between 6 to 7 hours. It is therefore essential that the swimmer is able to stay at least 6 hours in the water if he/she wants to guarantee a successful crossing.
Fog: The selected period for most swimmers is the summer, especially the month of August. In this month, dense fog usually forms, particularly in the hours close to sunrise and sunset. Such fog gives rise to two serious problems that could compel us to cancel the event. One is the possibility of losing sight of the swimmer, which would leave him totally abandoned and disorientated. The other is the risk of collision with some of the numerous ships sailing through the Gibraltar Straits, as it would be impossible for them to see the small boats that escort the swimmer. It is advisable, if at all possible, to avoid the month of August when the problem is made worse because of the great concentration of tourists in the area, which makes accommodation and a quiet stay difficult to find. Such adverse circumstances do not help the swimmer to be fully concentrated on the event.
The traffic of vessels: The Gibraltar Straits are one of the busiest maritime zones in the world, with up to 300 vessels sailing through daily, not counting the ferries which cross between the harbours on both coasts of the Strait and many fishing and pleasure boats. This gives rise to not only a risk of collision but also inconvenience if these vessels pass very close to the swimmer, as their bow-waves will always break the swimmer’s rhythm. To avoid such situations, we count on the invaluable and kind collaboration and support of Tarifa Traffic, which broadcasts security warnings at regular intervals so that the ships can give a wide berth to the swimmer’s position and to the escorting boats, for which we are eternally grateful. Apart from this, the escorting boats are equipped with all technical means to detect and get in touch with the ships that proceed dangerously towards the zone. In spite of all these measures, it is not always possible to prevent a ship paying no attention to the warnings and it could be necessary to raise the swimmer aboard the escorting boat in order to avoid a collision. This incident would be considered an exceptional case and the swimmer would be able to continue the crossing from the point where they were picked up. An additional risk that might arise is if, for an exceptional reason, the trip were extended overnight and the swimmer was located in the middle of one of the two traffic lanes. This would compel us to discontinue the event in view of the risk of the escorting boat being unable to follow the swimmer or detect them visually in sufficient time to avoid other vessels sailing through the Straits.
Currents: The influence of the currents and how to use them to help make a successful crossing has been described previously as almost impossible. In spite of all available data to forecast the general currents in the Straits, the calculation is not mathematical and it is still possible to come up against unexpected and prompt currents, which can interfere with the progress and direction of the trip. Because of this, the crossing is monitored from the escorting boats and Tarifa Traffic every half hour in order to check that the progress is in line with the previously established route and, if not, to take the appropriate measures. Normally, these measures consist of an appropriate change of course to avoid swimming against the current and in order not to extend the event unnecessarily. This problem has caused many swimmers to abandon the crossing after several hours, in some instances even when they were very close to the end of the event, as, due to weariness and drift, it was impossible to reach the Moroccan coast.
Sickness, vomiting and cramps: The appearance of such symptoms can be fatal for the swimmer and would make it advisable to abandon the crossing. The causes of these symptoms can be a number of things, among them the exhaust fumes from the engines of the boats; swallowing sea-water; swimming into polluted waters caused by oil spills; weariness and/or the cold. All of these are avoidable and the boats will be very careful to stay sufficiently far away from the swimmer so as not to disturb him/her. It is essential for the swimmer to be able to breathe from both sides so as to avoid the sea wind when breathing, as well as to avoid swallowing salt water.
Weather conditions:The wind is the most important factor in the accomplishment of the crossing and we will be waiting anxiously for the weather forecast for the selected day of the crossing and hope that the forecast will be for slight winds of variable direction or westerly winds. If not we will wait until the next day. Concerning the wind force, it is essential that it does not exceed force 3 or 4 on the Beaufort scale, although some crossings have finished in force 6 or 7 but have never started in this strength of wind. The Straits of Gibraltar and especially the area of Tarifa are a very special zone meteorologically speaking, as they have a micro-climate where sudden changes of wind and strong and persistent easterly winds prevail. Many swimmers have had to abandon the crossing after remaining in Tarifa for many days. It is for this reason that this area deserves special attention to the weather forecast issued for the Straits of Gibraltar. It has also been demonstrated that August and September are the months which present the least number of days with strong winds. Even though this does not serve to assure good weather conditions, it does increase the possibility of a successful crossing. The different meteorological bulletins are issued by the Maritime Centre of Tarifa, and the Association decides the best day and time for the crossing, in accordance with the tides. Once the crossing has begun with favorable conditions, the Association will be responsible for cancelling the crossing if the meteorological conditions change substantially from the forecast and the integrity of the swimmer is put in danger.