On May 21 2011 Eversafe Marine engineering company successfully launched a DWT47000 cargo ship with marine airbags in Nanjin Jinda shipyard. The ship named “ tai he da” weights 9000 tons, measured by 190 m length, 32 m moulded width and 16 m depth . The launch slipway is a concrete ramp with 1/80 slope angle. From end of slipway to the Yangtse river there is a 60 m natural ground paved with gravel. Yangtse river is one of the most busy channel so our launch is strictly limited for the launch time and launch area by local Maritime Safety Administration.
The elevation of launching ramp end is 2 m and stern draft is 1.7 m so stern will not be refloated when it is launched at 120 m distance. To remedy the practical disadvantage Eversafe team performed the detailed calculation of using ballast water to adjust the vessel trim angle during launch. At last 2000 tons ballast water was added into the bow cabin.
In the morning of May 21 our launch team begun to prepare all necessary work for the 40 m forward move and successional launch that must be completed within there hours. At 9 am the vessel transportation work started and got finished in one hour. According the plan this vessel will be launched at 12 am when the water reaches highest level in the day. Because of some emergency reason the local Maritime Safety Administration demanded the launch to be carried out at 10:30 am. So we got only 30 minutes to prepare the launch.
Water level in the launch area is 100 cm less than plan so marine airbags and ramp will bear more pressures than expected figures. People reinforced the conjunction of ramp with steel plates temporarily and adjusted pressures of airbags at stern. At 10:30 as soon as adjustment work finished pulling ropes from winches were chopped and the launch started. The vessel got total floatation at 300 m and stopped at 460 m distance.
After the launch people found there was a gap at launch ramp conjunction position. Provided without the temporary reinforcement the part of ramp may collapsed during the launch.
It is a very urgent launch project. Eversafe team depends on the scientific calculation and profound experience overcomed all practical disadvantages and did a great job. It is the fourth vessels launched by our company in this month . Airbag ship launching is proved to be successful and flexible in deficient conditions.
