No more waiting for good weather

Deep-water installation in harsh weather conditions made possible by active heave compensated hoisting system in which IHC combines extensive knowledge with hydraulics, automation, winches and heavy lifting technology.

60 extra working days for crew and vessel

The 400t active heave compensated hoisting system allows the heavy-lift vessel to perform more installation jobs each year, maximising return on asset investment.

Our client needed a 400t hoisting system to safely place heavy loads onto the seabed at a depth of up to 3,000 meters. To ensure maximum return on the asset investment, the system would have to be able to perform installation jobs in dynamic sea states.

active-heave-compensated-hoisting-system


THE CHALLENGE: deep-water installation in harsh weather conditions

During deep sea lifting and lowering operations, it is important to keep full control over the load to prevent it from slamming into the seabed. Regular Active Heave Compensators are designed to keep the lifting point steady in relation to the seafloor, compensating the movement of the vessel caused by swell and waves. In this case, however, the large working depths of up to 3,000 metres, added an extra challenge.

Over such great distances, even the strongest cables can stretch up to an additional 8 metres in length. So even if the lifting point is kept steady, the load can start bouncing (oscillating) due to the spring-like characteristics the cable develops in these conditions.





OUR SOLUTION: INTEGRATING THE ACTIVE HEAVE COMPENSATOR AND WINCH SYSTEM

By combining our extensive knowledge of hydraulics, automation, winches and heavy lift technology, we designed, engineered and constructed a system that integrates an active heave compensator and a winch system. It includes a storage winch for 3,500m of wire rope, the complete drive and control system with motion reference unit, and controls cabin.

Keeping loads under control

Requirements to safely transfer 400t loads to water depths of 3,000m with minimal energy consumption.

Advanced control system

Our dedicated control software identifies potential resonance hazards. It actively neutralises the typical frequency to avoid the risk of resonance. A safe lowering operation can be demonstrated by logging force, speed and accelerations during the entire lowering operation.

Load resonance avoidance

Resonance is a common challenge in deep-sea lowering. The IHC AHC system neutralises the typical frequency to avoid resonance without unwanted side effects.

Quick lift

The integrated quick lift mode is activated on the through of a wave to perform a controlled lift without risk of reimpact to the seafloor.

Smooth transition

Transition between splash zone mode, resonance avoidance mode, landing mode, active tension mode and quick lift mode is performed smoothly. This avoids sudden uncontrolled movements of the load.

Splash zone crossing

Instant wire load changes occur when entering the waves. Our AHC system keeps the hoisting wire tensioned – and minimises uncontrolled motion.

Subsea landing

A stepless, controlled and low landing speed is essential for a safe landing. Our integrated approach ensures the highest motion reduction even at water depths of up to 3,000m.



Neutralising resonance

The system not only balances out the motion caused by waves and swell; its dedicated control software also identifies potential resonance hazards and actively neutralises the typical frequency to avoid the risk of resonance. A safe lowering operation can be demonstrated by logging force, speed and accelerations during the entire lowering operation.

Smooth transition

Moreover, this advanced system has a splash zone mode that keeps the hoisting wire tensioned the moment the load enters the waves. The transition between resonance avoidance mode, landing mode, active tension mode and quick lift mode is performed smoothly to avoid sudden uncontrolled movements.



TECHNICAL SPECIFICATIONS

9.338 km
8.000 MM
Compensated stroke
350.000 m3
95 cent
Per motion
compensation
25 persons
3.000 M
Water depth
36 Vessel
400 tonnes
Workload