Development of a stacking frame system
Scope of work
Design and deliver a deck stacking frame system to carry 15 wind-turbine blades per voyage from Esbjerg/Aalborg to Taichung, enabling load/discharge with ship’s own gear and no shore crane. Operations included three discharge terminals and hook-height-limited working at up to 24 m above deck.
Methods
Concept and verification with AutoCAD, Inventor and RFEM/Ansys – covering frame layout, FEM of weather decks and structural checks for interfaces, lashings and weight spreading.
Engineering scope
Develop the stacking concept; run FEM analyses of the vessels’ weather decks; engineer weight-spreading into deck and hull; supervise frame fabrication and arrange delivery to the POL; adapt client rigging to limited hook height; plan and oversee load/discharge procedures (including working-at-heights measures) across three terminals in Taiwan.
Supporting Taiwan’s green energy expansion
Development of a Stacking Frame System for 15 Blades on Deck: Taiwan is undergoing a major green energy transformation. Landmark offshore wind farms such as Formosa, Yunlin, and Greater Changhua are central to Taiwan’s goals of cutting greenhouse gas emissions by 50% by 2050 and increasing renewable energy to 20% of total power supply by 2025.
The Jumbo-SAL-Alliance went full steam ahead to support this transition. The mission involved transporting 75 SG 8.0-167 DD turbines and 225 blades from Cuxhaven (Germany) as well as Esbjerg and Aalborg (Denmark) to Taichung (Taiwan). Multiple vessels – Type 176, Type 171, Type 116, and Type 161B – were involved in rolling operations.
However, vessel coordination wasn’t the biggest challenge. As Fabian Obert, Manager Chartering & Projects at Jumbo-SAL-Alliance, notes: “Our main challenge was to develop a stacking frame system for the blades, since they were not initially planned to be stacked by our client SGRE. Luckily, we had an amazing team of experts at SAL Engineering.”
Engineering a custom blade stacking system
To meet client requirements, a new system had to be engineered to safely transport the blades while maximizing intake. “We typically use a mezzanine deck for these types of projects, but in this case the intake was insufficient,” explains Jonas Wehling, Project Engineer & Naval Architect at SAL Engineering.
The goal: accommodate 15 blades on deck while ensuring that the vessel’s own cranes could handle both loading and discharge – without shore crane assistance.
SAL Engineering developed a bespoke stacking frame system that met all technical and operational needs, including:
- FEM analyses of the weather decks for load and stress validation
- Supervision of stacking frame fabrication
- Coordination of delivery to the port of loading in Aalborg
Three ports, one complex discharge operation
An additional operational complexity was that deliveries were split across three terminals in Taiwan, each serving different wind farm projects.
Handling each blade – 82.07 × 7.3 × 6.08 metres and 44.3 tonnes – required operations up to 24 metres above deck. Safety came first:
- All crew received special “working at heights” training
- Blades were handled exclusively using vessel cranes in tandem lift
- Clearance between blades during lifting was extremely limited
“Due to limited hook height, we needed to modify the client’s rigging arrangements – shorter rigging was required,” says Wehling. He adds: “We applied standard lashings for the sea passage, but a careful load-spreading arrangement was essential to safely transfer stack forces into the deck and hull.”
Adding to a greener tomorrow
The first blades and nacelles have now safely arrived in Taiwan and await offshore installation at the Formosa, Yunlin, and Greater Changhua wind farm sites. Shipments are expected to continue through mid-2022.
“With this project, we once again proved that SAL Engineering will find the right solution for even the most unique challenges. We are proud to contribute to these milestone green projects and look forward to many more ahead,” agree Fabian Obert and Jonas Wehling.