Monopile oscillation damping

XXL Monopile oscillations

During monopile (MP) piling operations, there are various stages where MP's are excited by forces from current, waves, wind, slewing inertia etc. You run the risk that MP's start oscillating, increasingly accumulating dynamic energy. When these MP's are becoming heavier and heavier (e.g. 3000mT), this starts to become dangerous: for the structural integrity of the crane, the gripper and other deck equipment. But also for accuracy of installation. All in all, the level of control over the operation drops significantly

The Full Motion Chief 3000 can dampen MP oscillations,...

Using a heavy version of our Full Motion Chief, the FMC3000, you can control these oscillations. This can be done for double (see examples here) and single pendulum motions. This keeps the MP much stabler, reduces side- and off lead angles on your crane, and dynamic forces on the gripper.

,.... and holds the MP still above the seabed in floating installations

Besides pendulum damping, the FMC3000 has the same level of heave control as our standard Heave Chiefs. The tool keeps the full MP steady within a +/- 5cm vertical bandwidth, even if your crane hook moves up and down in waves of Hs 3.0m. This is especially helpful for low-noise MP jetting operations: if the distance to the soil is constant, the driving of the MP is faster, and more controlled. Plus, the vertical tension control allows crew to much easier handle the variation between soil conditions: when reaching denser soil layers, the FMC3000 simply buffers its mechanical stroke, and can keep the tension in the crane wires constant.

Gripperless installations?

Is a future foreseeable where installations without expensive grippers (~€50Mn?) might be an option? or at least make them simpler? Two important reasons for using grippers is to keep control over the MP during a pilerun, and to ensure the inclination and position remain within limits during the entire process. Jetting technology takes care of the pilerun risk, as it basically dredges itself into the soil. Using the FMC will definitely help with getting control over those dynamic elements. Currently we are investigating what further steps are needed to work towards this future.

Download study results

Seaqualize did simulation studies, on all steps of a jetting operation. We've taken typical installation limits into account, and show how much difference the addition of the FMC3000 can make, how many days and €'s on spread costs are possible. Have a look below!