Salvage grabber automation

Salvage grabber automation

In 2004 an oil tanker passing through the Malacca Strait collided with a vehicle transporter carrying four thousand cars, making a hole in the hull. The ship sank to the sea bed off the Singapore coast. Smit Salvage was the party to recover the vessel, measuring nearly two hundred metres.
Smit asked Idea to come up with a design for a new grab, based on an existing 11 metre wide model. The redesign would need to deliver increased gripping capacity and allow work to be carried out at a greater depth.

It resulted in a grabber with the following characteristics:

  • Weight in air : 250 tonnes
  • Grabbing capacity : 600 tonnes
  • Maximum grabbing force : 300 to 900 tonnes (PLC controlled)
  • Control system : PLC Siemens S-7
  • Monitoring systems : Pressure, temperature, camera, lights, heading, inclination, position

The grab in operation is connected to the blocks of a sheerlegs crane to control the hoisting height/depth of the grab. The grab itself is equipped with three vertical mounted hydraulic cylinders for opening and closing of the grab. The cylinders are actuated by means of a subsea power pack mounted within the steel construction of the grab. The electrical power supply to the grab is provided by an umbilical from the main deck of the sheerlegs. The grab operation is PLC (Programmable Logic Controller) controlled and the operation can be 
monitored from the control room at the surface.

DISA took care of all PLC programming on the project as well as of writing dedicated monitoring software functioning in the control container.

Client: Seascape
Period: 2007
Location: Rotterdam, Holland