AWT Weather Routing/Routeing: Applied Weather Technology

The Effect of Piracy and the Southwest Monsoons on Routes

At the time of writing this article, war zones published by the Joint War Committee established the war zone for the Gulf of Aden as:

a) on the west, longitude 45E
b) on the north, latitude 15N
c) on the east, longitude 57E
d) on the south, latitude 10N

Then 250NM east of Somalia, and in the Indian Ocean extending 600NM east of the African coast until 10S with some stated exceptions.

The Maritime Security Patrol Area operates within this war zone in the Gulf of Aden.

Historically, routing guidelines for voyages across the Arabian Sea during the summer monsoons call for tracks which limit exposure to the heaviest SW winds and waves in the region. The following map shows in green a seasonal route from maritime publications. It clearly runs through the listed areas from the Joint War Committee.

However, the track shown in red is one of the possible alternates for those vessels attempting to remain outside of the war zone until nearing the Maritime Security Patrol Area.

It can be seen that during the summer months, vessels will need to work against the monsoon winds in an area where the greatest likelihood of high waves generally prevails.

However, AWT has found that global weather patterns can greatly affect the strength and positioning of the monsoon core. Utilizing many years of historical wind and wave data, the following images depict the areas where speed loss is highest for westbound vessels during the peak of the monsoon season under two different weather patterns. The differences are striking and indicate that routing based on climatological averages in the region can be advanced.

While AWT can recommend courses to mitigate the effects of the monsoons, ship operators should be prepared for delays in the coming season over and above what was previously experienced, as routes many have longer distances than during the last monsoon season and ships will likely encounter higher speed losses as they work their way across the western Arabian Sea with the SW monsoons off the port bow. Additionally, predicting arrival time for entering the corridor, westbound, will be made more difficult.