Haul out vessels with marine airbags

Above pictures are from http://www.eversafe-marine.com/

Haul out vessels with airbags especially suits for emergency such as hurricane coming. With airbags people can haul out vessels and transport them to safe place for store. For ship repairing company use airbags to haul out vessels can improve  his operation  capacity and need tiny enhancement of present slipway.
Using marine airbags to haul out vessels can overcome the limitations of instruments and slipways and make haul-out work easy. The haul capacity of this system is decided by the pull winch and slope angle of slipway or ramp so it is easy to get improved. Generally speaking up to 4,000 tons vessel can safely be hauled out using airbags.
The basic principle of airbags ship launching or haul-out is changing the force of sliding friction into rolling friction, just like ancient Egyptian using logs to transport heavies. The rolling friction coefficient of airbags and ground is decided by the ground situation and airbags’ bearing forces. People can use 0.006-0.01 as the estimate figure if the ramp is concrete. 
The essential instruments of airbag haul-out system include winches, rigging and marine airbags. To complete a successful haul-out project the following conditions should be satisfied.
Enough pulling capacity of winch. Normally the maximum pull force should be 1.5-2 times of the calculated result.
Appropriated ramp. It is easy to understand the angle of slope decides the needed pull force. The bearing capacity of ramp must be higher than the maximum inner pressure of airbags. For big vessel, the professional designed concrete slipway is needed. Generally airbag haul-out slipway gets one underwater part which has bigger slope and another shore part with smaller slope.
Suitable airbags. Airbags with 1 meter diameter are most often chosen since working heights of airbags for haul out usage are about 30 centimeters. And for bow lifting, shorter airbags are convenient to use.
Good water level. When the bow is lifted by inflated airbags, the stern should not contact the seabed unless it will be difficult to pull the ship out of water.
Clearance of shucks and anything else under vessel’s bottom that will damage airbags or baffle the rolling of airbags.

Two Years Two Ship Launching Accidents Happened in one Shipyard

One Korean Shipyard located in China Weihai got two ship launching accidents in two years. The first accident happened in 2009 that a new built 6700 units PCTC sunk at launch. And that PCTC have not been salvaged from the sea until the latest launch accident happened. On January 21, 2011 in the same launch area one new built cargo ship grounded when it was launched from a floating dock.

Two new built vessels capsized when they were launched by the floating dock that is the true ridiculous story of a Korean shipyard located in China.

On March 28, 2009, a new built 6700 units PCTC sunk at launch.. The shipyard said the carrier crushed into reefs(?) when it was launched by a floating dock and water flushed into cabin from the broken broadside that caused the carrier’s rollover. People try to balance the carrier by making another gap at the opposite broadside but 4 hours later the carrier sunk into 10 meters deep sea bed. Then that PCTC stayed in the sea for about two years until the latest launch accident happened.

                                     The 6700 units PCTC capsize at launch

 

On January 21, 2011 in the same launch area almost same story happened again. Water flushed into engine cabins of the new built cargo ship which was prepared to be launched in a floating dock. Eventually cargo ship slipped out of floating dock before it was total floated and grounded by its stern. It is said the floating dock was somewhat damaged also.

From the shipyard’s website people can see their goal is to be NO. 1 of the shipbuilding company in the world.