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DNV GL "Twisties" Joint Industry Project

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Chris Garrett Chris Garrett
Senior Engineer, Offshore Wind Farm Installation

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Twisties JIP
This Joint Industry Project (JIP) is the first step on the deployment of the Fast Feeder Vessel concept for offshore wind farm installation. The JIP will develop a Recommended Practice for the unitisation of project cargo using “Twisties”, and in particular usage of the Twistie Turbine Cassette in offshore wind turbine storage, transportation and installation.

Background
The increasing size and quantities of wind turbines installed, both onshore and offshore, means that a change in requirements is needed for shipping project cargo between manufacturing and marshalling port facilities, and feeding Wind Turbine Installation Vessels (WTIVs) offshore.

Feeder vessels allow WTIVs to focus on installation and stops them being expensive inefficient cargo vessels.

But feeding has historically introduced a lifted, offshore vessel-to-vessel transfer of components. With floating feeder vessels this introduces two limitations – wave height and wind speed limits. Jack-up feeder vessels avoid the wave limits, but it means there must be two weather windows for blade lifts. The Fast Feeder Vessel uses a RoRo method of vessel transfer and can therefore, avoid both wave-limits and the tight windspeed limits associated with lifting blades offshore.

This constant requirement for handling project cargo of a repeatable form has brought around the need to optimise and standardise the transport logistics and sea-fastening arrangements associated with the multiple, uniform project cargoes handled by the offshore wind industry.

Project objectives
Together with industry stakeholders, DNV GL aims to establish a Joint Industry Project (JIP) to develop a Recommended Practice for the unitisation of project cargo. Some cargoes are suitable for containerisation, but offshore turbine components are too large for this. We have seen attempts made at unitisation, such as the wind industry grouping sets of three blades into a “unit”.

Modular twist-lock, stackable blade racks are now commonplace on the decks of installation vessels. We have taken this concept and proposed a method for unitisation, by using modular transportation and sea fastening frames, based upon standard 20' container twist-lock centres. The concept is called the DNV GL “Twistie” - a modular project-cargo transport frame system.

Deliverables
An industry guidance document will be developed and published as a “Recommended Practice” (RP). The document will be subject to wider industry stakeholder consultation and will become publicly available after project completion.

Following the completion of the JIP, a project report will become available to the participating parties only and will capture key findings, knowledge, and experience.

It is also hoped that the partnership will remain together into a demonstration phase and beyond as the concept is implemented.

Participants
Together with DNV GL, the project will be sponsored by stakeholders with a genuine interest in the unitisation of project cargo in the wind industry. The project will be managed by offshore wind experts located in DNV GL’s London and Bristol offices in the UK. Project meetings will likely take place in the UK with wider participation facilitated by video conferencing when necessary.

Timeline
The project will commence in 2016, with a likely duration of one year. The Recommended Practice development, review, and publication are envisioned for 2017. The demonstration phase would commence immediately after the RP document is completed and it is anticipated that it would have a duration of 12-18 months before the concept is honed for commercial implementation.

Cost and budget
There is a project participation fee. A total of 10 to 20 participants are expected to participate in the project. The project participation fee will be finalised when the precise scope of work is agreed by all partners.

Join the JIP
To join the JIP or for more information, please contact us.