Ulstein unveils new monopile installation technology
Ulstein’s U-Stern design will enable more efficient monopile installation (Source: Ulstein)
Ulstein Design & Solutions BV has released details of the patent-pending Ulstein U-SternTM, a safer and more efficient way of transporting, upending and installing large monopiles with dynamic positioning (DP) accuracy.
The U-Stern system involves the longitudinal carriage of monopiles, a transverse and longitudinal skid system to locate them on the ship’s centreline ready for a crane to upend them and position them via a recess at the stern of the vessel.
The new technology enables the ship to face incoming weather, thereby reducing ship motions and saving fuel. And the design of the stern provides further protection from waves.
The company’s product manager and lead naval architect, Ko Stroo, explained that the U-Stern is more than a simple recess. “The shape and location of the recess are finely tuned with computational flued dynamics to make it work in harmony with the crane and mission equipment,” he said.
Managing director of the design company, Edwin van Leeuwen, commented; “The idea of longitudinal monopile installation originates in our vast experience in developing heavy-lift pipelay vessels with a centreline firing line. The U-Stern is however not a ‘one-trick pony’, as the vessel is also suitable for jacket installation and other heavy-lift installation work. In the past months, we have presented the U-Stern to major contractors and operators, many recognising this as the most viable solution for installing the next-generation monopile foundations.”
The new design offers a range of benefits compared with traditional over-the-side monopile installation arrangements. They include a reduction in motions of up to 25%, allowing more uptime; a 50% reduction in DP power requirements due to weather-vaning; avoiding challenges relating to transverse monopile transport and upending; and safer lifting operations offshore.
