From March 12 to April 18, 2017, the Ulysse, an AHTS in the BOURBON fleet, towed a barge of offshore equipment for Saipem, from Arbatax, in Sardinia to Port Harcourt. Story.
Departing from Arbatax in Sardinia on March 12, the Ulysse reached Onne-Port Harcourt in Nigeria in 38 days. Its mission: to tow a barge loaded with offshore equipment for Saipem, as part of Total's Egina offshore project. "The vessel had just completed a mission in Egypt. She was immediately contacted for this towing operation," explains Gontran de la Souchère, Contracts Manager with BOURBON.
The Ulysse, an AHTS with a bollard pull of 170 tons, was custom made for this type of mission. "One of the Ulysse's advantages is that she has a variable bollard pull, thanks to her 4 engines. Depending on the load to be towed, she can mobilize 1, 2, 3, or 4 engines. It's ideal for saving fuel while ensuring optimal bollard pull," points out Lionel Le Pape, her captain. For this towing operation, the Ulysse only used a single engine, for a daily consumption of 10 m3 of fuel.
To cross the 4500 nautical miles separating Arbatax from Onne, the Ulysse traveled at an average speed of 5 knots. On board, she had 12 crew members. On this type of mission, you have to keep your eye at all times on the tension on the towing line. "Without ever touching the bottom, the cable has to be long enough to be in the water and act as a shock absorber in the event of bad weather. The goal is to minimized unplanned stops, which burn a lot of fuel," the captain adds.
Towing a 100 m barge with a 500 m tow line reduces the room for maneuvering. Especially in narrow areas like the strait of Gibraltar, which concentrates one third of the world's maritime traffic. "13 kilometers wide, it's not much to accommodate all those vessels!" stresses Lionel Le Pape. "We took the care to communicate our maneuvering intentions to the other vessels in order to prevent an accident."
Another success factor: seizing meteorological opportunities. "Leaving from Sardinia, the weather was with us, with an easterly wind that pushed us in the right direction. So we were able to go a bit faster and catch a favorable weather window off the coast of Morocco. It was a chance not to be missed, because the headwinds in this area can be fairly violent," Lionel Le Pape explains.
As we approached Nigeria, the Ulysse went to Level 2 security and a very strict protocol was set in motion. "A Nigerian naval vessel then joined us and escorted us to port," the captain concluded.