Cranemaster was recently used for deployment of a large mudmat (13,75 x 13,75 meter) at 1788 meter in the Gulf of Mexico. For ease of operation, the mudmat was deployed horizontally.

Considerations to be handled by Cranemaster

  • The unit should have enough load capacity to support the dynamic loads during all phases of the installation.
  • The length of the unit should allow for deck handling during deployment.
  • At any stage in the installation, the unit should be able to stroke but not extend to the maximum allowable limit.
  • The stiffness of the unit should be sufficiently low to eliminate the risk for lowering resonance zone during the lowering to depths.

Lift analysis

A feasibility study was conducted, demonstrating the benefit of adding Cranemaster to the operation.

The following phases were analyzed:

  • Lift off from the supply vessel.
  • Deployment through the splash zone.
  • Lowering and resonance check at every 200m till 1700m depth.
  • Seabed landing.

The operation went very well and Cranemaster significantly extended the weather window for the installation.

Mobilization and demobilization was handled by our US representative Marine & Industrial.

Passive depth compensation

The Cranemaster® unit CM3-75T-4000 with passive depth compensation (CMDC) was chosen for this project for its unbeatable advantages. CMDC is a patented1) robust, passive depth compensation solution especially made for deep water operations. For a soft and controlled landing, the stroke capacity is maintained throughout the lowering phase and potential resonance during lowering is eliminated. The unit was configured to handle both splash zone crossing and subsea landing with the same setting, which was enabled by the CMDC.

We are experiencing an increasing interest for Cranemaster® units with passive depth compensation (CMDC) and they have recently been used for installation of similar structures in deep waters.

1)InterMoore Inc., the owner of US patent 7934561 “Depth Compensated Subsea Passive Heave Compensator”, has granted Cranemaster an exclusive worldwide right of the use of this patent.

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