4 minute read
Safeway unveils new gangway
DESIGNED FOR GROWING SOV MARKET
A rendering of the Safeway Gannet.
SAFEWAY, THE OFFSHORE ACCESS SYSTEM COMPANY IN THE VAN AALST GROUP IN THE NETHERLANDS, HAS ADDED NEW FEATURES TO ITS RANGE OF MOTION COMPENSATED GANGWAYS.
ALL IMAGES COURTESY OF SAFEWAY.
Van Aalst Group CEO Wijnand van Aalst.
The company has incorporated the features into a new gangway, Safeway Gannet, for next-generation requirements, such as the service operation vessels (SOVs) being sought for offshore windfarms on the Dogger Bank in the North Sea. “The Safeway Gannet 3D motion compensated offshore access system was developed in response to evolving requirements for walk-to-work systems,” explains Van Aalst Group CEO Wijnand van Aalst, “such as those being sought by Equinor and its partners for the massive offshore windfarms they plan to build on Dogger Bank. However, it is equally well suited to emerging requirements elsewhere, such as in Taiwan.” Equinor has issued a tender for a new class of SOV for its Dogger Bank projects, a tender that is particularly demanding for several reasons. The first is that the access systems installed on the vessels will need to be able to connect and transfer personnel and equipment in a significant wave height of 3.5m Hs, compared to the industry norm of 2.5m Hs. The second reason is that the SOVs on which the motion compensated gangways will be installed will be somewhat smaller than those operating in the North Sea. SOVs built to date for operation in the North Sea are in the order of 80-90m in length. Those for Dogger Bank will be 70-80m long. Smaller vessels will be less expensive to build and operate but, given that a vessel’s stability usually increases in relation to size, opting for smaller ships will make motion
compensated access harder to achieve without adopting walk-to-work systems that are more capable than existing equipment.
Hover mode and roll compensation Safeway’s motion compensated gangway has various unique features, including its well-known ‘hover mode’ and its roll compensation capability. Hover mode means that the gangway does not physically push against the landing point on a turbine or offshore structure, so you can land at your preferred location. The freedom of landing point that you get with hover mode is a big advantage because it means you can select the best heading for the vessel towards the waves, regardless of the conditions, and maximise workability. Roll compensation has become an increasingly important capability, as the height above sea level at which windfarm technicians need to be transferred has grown. Any vessel, however well designed, will experience some rolling motion, but its effect on a gangway when extended increases as the height at which transfers take place grows.
A lot of existing equipment was designed with a transfer height of 20-21m in mind, but as wind turbines have grown and more windfarms are built in areas with significant variation in conditions and water depth, so gangways need to be able to safely transfer personnel at 28-30m or more above sea level. At that kind of height, even a small
Photo courtesy of Safeway.
Pictured here is the Safeway Seagull from which the Safeway Gannet is derived.
amount of vessel roll can make big difference. To date, gangways have compensated for this with a high telescoping speed, but this can lead to a certain amount of resistance from personnel being transferred, according to Mr Van Aalst. He voices, “A lot depends on the telescoping speed, but when it is high, the personnel on a gangway can experience being moved towards a fixed object as quite uncomfortable.”
Apart from enhanced safety and greater confidence in the use of a gangway, Mr Van Aalst comments that combined with hover mode, this also reduces the time it takes to transfer personnel and their equipment. “We believe that compared to a system without roll compensation, you can complete transfers 25-30% more quickly”, he claims, which translates into a significant timesaving and cost reduction. Like some of the other Safeway gangways, the Safeway Gannet will also be able to transfer cargo using the hook on the tip of the gangway. Safeway’s gangways are currently capable of lifting 1,000kg, but the Safeway Gannet will provide an option for lifting 2,000kg, a level of capability that is also understood to have been specified by Equinor. In addition to personnel and cargo transfer, the Safeway Gannet can also carry trolleys of the type that many offshore operators like to use to take equipment and tools across to a turbine. By combining trolley operation with cargo lifts, Mr Van Aalst exclaims Safeway is confident that the Safeway Gannet will be popular in the demanding and fast-growing SOV market worldwide.
