What is subsea landing speed analysis?

Subsea landing speed analysis involves assessing the descent or landing speed of a structure, equipment, or component onto the seabed in underwater environments. This analysis is a crucial aspect of subsea engineering, especially in offshore industries, where precision and control during the landing process are essential to ensure the success of subsea installations.
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Key considerations in subsea landing speed analysis include:

Controlled Descent:

Evaluating the descent speed to ensure it is controlled and within acceptable limits. Uncontrolled or excessive landing speeds can lead to structural damage, seabed disturbance, or other operational issues.

Structural Integrity:

Assessing the impact of the landing speed on the structural integrity of the subsea structure or equipment. Excessive speed can result in increased forces upon impact, potentially causing damage.

Seabed Conditions:

Considering the characteristics of the seabed, such as composition and stability, to determine the appropriate landing speed. Soft or uneven seabeds may require adjustments to the landing speed to prevent issues like tilting or sliding.

Alignment Accuracy:

Ensuring that the landing speed allows for precise alignment with existing subsea infrastructure or other components. Accurate alignment is crucial for successful integration into the overall subsea system.

Dynamic Conditions:

Accounting for dynamic conditions, such as currents or underwater turbulence, that may affect the landing process. These conditions can influence the descent speed and require adjustments to maintain control.

Safety Factors:

Incorporating safety factors into the analysis to ensure that the landing speed is well within the designed limits and that there is a margin of safety to account for uncertainties or unexpected conditions.

Deployment Method:

Considering the specific method of deployment or lowering the subsea equipment. Different deployment methods, such as using cranes, winches, or remotely operated vehicles (ROVs), can influence the landing speed and control mechanisms.

Real-Time Monitoring:

Implementing real-time monitoring systems to track the descent speed during the landing operation. This allows for adjustments to be made promptly if deviations from the planned speed occur.

Regulatory Compliance:

Ensuring that the planned landing speed complies with industry regulations, standards, and guidelines governing subsea operations.

Subsea landing speed analysis is typically part of a comprehensive subsea installation plan. Engineers and operators use simulations, modeling, and calculations to predict and optimize the landing speed, considering various factors to achieve a safe and successful subsea landing. Adherence to best practices and industry standards is crucial to minimizing risks and ensuring the integrity of both the subsea equipment and the surrounding environment.

Typical challenges during the subsea landing operation

During the landing operation, there is often a limited operational weather window to reach required vertical landing speed. Many structures also have landing speed limitations and a tight angular tolerance. Exceeding these might cause overstress within the structures.

Rapid heeling of vessel during landing of heavy loads, might also pose a substantial risk.

These risks can be effectively mitigated by using a Cranemaster heave compensator during the subsea landing. The benefits include:

  • Reduction of landing speed.
  • Possibility to maintain tension in wire during landing phase.
  • Reduction of peak loads in case of re-lifting.
  • Prevention of rapid heeling of vessel during landing of heavy loads.

Our engineering department can assist in creating a virtual model of the subsea landing operation and run simulations that expose the risks involved within different scenarios. The simulation will then accurately predict the benefits of utilizing a Cranemaster unit, resulting in mitigating risks and saving time and money. Read more.