Offshore Wind O&M Challenges Solutions: The Neptune Jack-up vessel assisted by the boomlock system

Nicolas Degand
GeoSea Maintenance, Antwerp, Belgium


The Offshore Wind industry and its supply chain are continuously being challenged to further reduce costs. This trend, evidenced by the latest offshore windfarm tenders, clearly indicates the dedication from major industry players to substantially reduce the LCOE and ultimately make offshore wind subsidy free. Consequently developers become less and less dependent on unpredictable political interference, which combined with the current availability of equity, will further boost industry growth with increasing focus on reducing O&M costs.

With O&M costs representing around 25% of an offshore windfarm’s lifetime costs, it represents an important opportunity of cost reduction.

Offshore windfarm O&M costs are predominantly driven by wind turbine size, wind turbine technology, the size of the windpark, and its distance from shore.

Wind turbines technologies are evolving at a rapid rate. Both turbine hub heights and rotor diameters are increasing to capture more wind resource. This has led to higher power ratings, larger components and bigger capacity factors to transform more wind power into electricity. Although turbine OEMs have applied lessons learned from previous turbine models to ensure good levels of reliability, these new technologies will have to pass through a learning curve with some unpredictable challenges to overcome.


Additionally, as turbine power capacity increases the resulting potential downtime of a single turbine will have a bigger cost impact. Fast response times, the availability of suitable vessels and efficient major component replacements will be key.


As a result, here will be an increasing need and demand for vessels and tools that are able to handle these new and larger components whilst minimizing power production down-time.


Offshore wind farms are constructed further and further from shore and have to cope with extreme harsh environmental and site specific conditions. Special purpose designed O&M vessels and Jack-ups, used to support a variety of required scheduled and unscheduled service and maintenance activities, will need higher workability to safely and comfortably transfer people and handle components through higher wave heights and faster wind speeds. With a reduced amount of suitable weather windows to plan the activities, there is undoubtedly room for technological innovation to reduce the O&M costs.



With the development of more efficient vessels, capable of transiting and jacking-up in harsher conditions – weather downtime has been pushed back to the lifting operation. The biggest factor in weather downtime is waiting on the wind to drop so that blades and other wind sensitive components can be safely removed and installed offshore. Current wind limits are at 11 m/s (and as low as 8 m/s for some components). In order to overcome these challenges and allow for lifting turbine components in higher wind limits, the Boom Lockę system has been developed.


The Boom Lock system is an intelligent guidance system that allows an offshore crane to install wind turbine components at wind speeds that were previously impossible to work in. Capable of lifting multi-MW turbine blades in 15m/s winds, the Boom Lock system allows complete control over the hoisted load during the lifting process.

The Boom Lock system also takes a new approach in being the only system on the market which is designed to be turbine-independent (instead of being designed to fit only one turbine type/make) and can be used by all manufacturers, contractors and jack-up owners.


The JUP Neptune owned by Geosea, is fitted with the Boom-Lock system and is used by GeoSea Maintenance NV, to provide services to the offshore wind farm O&M sector. This makes the vessel unique in the market and provides customers the opportunity to maximize their wind park availability through minimizing production down-time during scheduled and unscheduled maintenance.