The water temperature in the Strait of Gibraltar can range between 15 degrees in winter and 22/23 degrees in summer. Therefore, it is advisable to try crossing in the spring or summer period where the risk of hypothermia is lower. The duration of the crossing depends on the characteristics of each swimmer and the sea conditions and currents, being able to estimate between 4 to 7 hours. It is therefore essential that the swimmer is prepared to stay at least 6 hours in the water if he wants to guarantee the crossing successfully. To fight against this time in the water it is convenient to protect the body with some type of fat based on lanolin, except the face and hands, which will act as temperature sensors. Or in another case, wear a wetsuit.
The association organizes the crosses from April to October, varying the temperature from 16/17 ºC to 22 / 23ºC.
The period chosen by most of the swimmers is the summer, and within it the months of July and August. In these months are frequent formation of advection fog (mass of warm and humid air in contact with mass of colder water) that can be of great intensity in the hours near the sunrise and sunset. This fog create two serious problems that would force to suspend the swim: one of them is the possibility of losing sight of the swimmer, which would leave him completely unassisted and disoriented; the other is the risk of collision with one of the numerous ships that cross the Straits due to the impossibility of sighting small escort boats.
The maritime authorities only allow crossings with a visibility of at least 5 miles.
The Strait of Gibraltar is one of the busiest maritime avenues in the world, with a traffic of more than 300 container ships per day not counting the ferries that make the crossings between the ports in area, as well as numerous fishing and sports boats; this entails a risk not only of collision but of discomfort if said vessels passed very close to the swimmer. To avoid such situations, we count on the invaluable collaboration and support of the Maritime Rescue Centers of Tarifa and Tangier, which issue saftey messages at regular intervals so that the vessels provide ample protection to the position where the swimmers are located. Likewise, the escort boats are equipped with all the technical means to detect and get in touch with the vessels that proceed dangerously towards the area. In spite of everything, we cannot rule out that some ships may ignore the warnings and it may be necessary to pull the swimmer on board the boat to avoid collision; said incident will be considered as an exceptional case and the swimmer will be able to continue the crossing from the same point of his boarding, previously registered by the guide boat.
Previously, the influence of currents and the way of crossing has been described, in such a way that even these currents can be used in favor of the swimmer. Despite all the available data to predict the general flow of currents in the Strait, its calculation is not mathematical and we can find unexpected and punctual currents that can hinder the advance and direction of the crossing. Therefore, from the support vessel is monitored every half hour to check if the evolution meets the forecasts and take the necessary measures otherwise. Normally these consist of an appropriate change of course to avoid swimming against the current and unnecessarily lengthen the duration of the swim, or in most cases, ask the swimmer / s to increase the pace and speed for several hours and even, in some cases, when they were very close to finishing the journey, because, due to fatigue, the drift made it impossible to reach the Moroccan coast.
The wind is the most important factor to be able to make the crossing and will have to be very aware of the weather forecasts of the day selected for the swim, expecting that the prediction will be of winds of variable direction or western component. If not, we would have to wait for the following days.
The maritime authorities only allow crossings with wind force 3 on the Beaufort scale.
The Strait of Gibraltar, and especially the Tarifa area is a very special area (meteorologically speaking) presenting a microclimate where sudden changes in winds are common and persistent easterly winds predominate. Numerous swimmers have not been able to do the swim after staying many days in Tarifa. That is why this area deserves special attention within the meteorological forecasts, which are issued for the area of the Strait and that, nowadays, can be consulted on the Internet. Likewise, it has been verified that it is the months of August and September that, statistically, have fewer days of strong winds, although this does not serve to ensure good weather conditions, it does increase the chances of success.
The of Maritime Rescue Center is responsible for ensuring that the swim begins in good conditions of wind, sea and visibility. Once the swimming begins with favorable conditions, the organization will be in charge of the suspension if the weather conditions deviate substantially from the predictions and the safety of the participants is compromised.
LINKS WIND PREDICTIONS
We remind the swimmers that the pilots will made the interpretation of the forecasts. So these links are provided for have a reference, but it is these experienced pilots with the time of the area who will determine the day and time of the crossing.