Longitude pioneers analysis of dynamic lowering operations for wind farm construction

(WK-intern) – Longitude Engineering – a specialist marine engineering subsidiary of the LOC Group – working closely with Rampion and its contractors, has developed an innovative analysis and modelling process to fully understand why large monopiles oscillate in relatively small wave heights; and to increase the operating window for their installation.

Monopiles and turbines are increasing in size as wind farms move farther offshore.

At the Rampion Offshore Wind Farm, which is currently under construction off the south coast of the UK, the developer was concerned that these large structures were beginning to oscillate in relatively small wave heights.This was affecting the operational window for lowering them into position.

As installation limits are generally set by operator experience, Rampion recognised that the oscillation had the potential to cause difficulties and invited Longitude to work with them to develop a more in-depth understanding of the problem and to assist with developing solutions and more rigorous guidelines.

Peter Kingsland, Principal Consultant/Naval Architect at Longitude explains:

“The piles used for the Rampion site weigh up to 850 tonnes which is close the working limit of the crane. Dynamic effects can lead to much larger forces than purely static loads and so it was important to understand the conditions which caused the piles to oscillate. We developed a numerical model of the pile and the rigging which we ran under a variety of conditions.“

„We also oversaw a series of tank tests and advised on and post processed data from instrumentation on the jack-up vessels to measure the motion of the piles as they were being lowered. This allowed us to develop a robust set of operating guidelines which gave confidence to Rampion and its marine warranty surveyors that pile installation would remain safe.“

„In effect, working closely with Rampion and its contractors, we were able to widen the safe operating window to give more flexibility to the installation process.”

In addition to this, and following an initiative from Rampion, Longitude also collaborated with the manufacturers of the crane tugger winch control system to numerically model its functionality and to develop an enhanced control system that would sense and damp down the motion of the piles.

This innovative work was coordinated and implemented by Rampion Offshore Wind and is the first of its kind to be developed and applied to the offshore windfarm sector and has the potential to be used in a variety of other offshore applications.

Longitude has a proven track record of working on a variety of renewable projects including cable installations, vessel conversions metocean studies, wave and tidal energy devices, wind farm component transportation and subsea deployment.

This latest project represents just one of the ways Longitude is working alongside the renewables sector to develop current methods and improve design capability.

Longitude Engineering is a specialist engineering consultancy dedicated to providing marine design and analysis services to the marine, offshore, renewable energy, superyacht and small craft market sectors.

It provides field operators, installation contractors, vessel owners and others involved in the industry with all the maritime engineering assistance they require to ensure their projects are successful.

Longitude Engineering was founded by leading international marine warranty surveying consultancy, LOC Group, in 2006. Since then, Longitude has opened offices in Singapore, United States, United Kingdom and Mexico. It is staffed by naval architects, structural engineers, composite engineers and marine engineers all with extensive experience of the offshore, marine, superyacht and small craft industries gained whilst working in a broad spectrum of the maritime industry.

The Rampion Offshore Wind farm is being built 13km off the Sussex coast by E.ON, the UK Green Investment Bank plc and Canadian energy company Enbridge.

The 400MW project is due to be completed in 2018.

PR: LOC Group

Internet: http://www.longitude-engineering.com/