Schottel propellers for new DF heavy-lift vessels

The contract has been signed with Wuhu Shipyard, China, which will construct the vessels for a commercial joint venture – Jumbo-SAL-Alliance -between German shipping company SAL Heavy Lift and Netherlands-based Jumbo Shipping. Delivery of the four firm plus two optional SCPs for the Orca Class newbuilding series will start in summer of 2023 for the first vessel. The last shipment is scheduled for 2025. 

The four-bladed controllable pitch propellers type SCP 129 will feature an input power of up to 8,810 kW and a propeller diameter of six metres. 

The vessels measure 149.9 m x 27.2 m and provide a capacity of 14,600 dwt. Despite their compact outer dimensions, the vessels have a box-shaped single cargo hold with the largest dimensions in their class. 

In addition to the optimised hull form, the innovative engine and propulsion concept including a booster function offers a hybrid setup with the widest available range of economic speed settings and redundancy, while also reaching a maximum vessel speed of about 18.5 knots.

As soon as green methanol becomes available in key ports, the Jumbo-SAL-Alliance will be able to offer their customers carbon-neutral transport solutions following the sustainability goals of the Harren Group. The first two units will be exclusively involved in the transportation of offshore wind farm components in a long-term commitment with Siemens Gamesa Renewable Energy. A holistic, sustainable approach including lowest achievable emission values was prerequisite for the award of the relevant contract.

Schottel SCP performance in model tests

In order to find the optimal propulsion set to reach these targets, the results of hydrodynamic calculations from three market competitors, including Schottel, were analysed by a committee of the two renowned independent model test facilities China Ship Scientific Research Center (CSSRC) and the Shanghai Ship and Shipping Research Institute (SSSRI).

The open water, self-propulsion and cavitation model tests were carried out and evaluated according to SAL’s pre-defined requirements, such as propeller efficiency, cavitation behaviour and propeller-induced hull pressure pulses. They verified Schottel’s customised propeller design with an almost cavitation-free operation and an optimized open water curve meeting SAL’s requirements to their fullest satisfaction.

“We’ve worked well with Schottel for many years, but at the same time wanted to be sure to select the best propeller design for our newbuilding as well. Therefore, it was clear to objectively compare all different competing propeller designs,” states naval architect Florentin Edler, project engineer at SAL Engineering GmbH. “When it now came to equipping the Orca Class, Schottel’s hydrodynamic team once again had proven their expertise which was the key to them winning the contract.”

“New standards in global heavy-lift shipping”

“The Orca Class is setting new standards in global heavy-lift shipping. They represent the new benchmark both in terms of their technical capabilities and modern climate-friendly propulsion systems,” says Dr. Martin Harren, Owner and CEO of SAL Heavy Lift, SAL Engineering and the Harren Group. “The ships will be the most efficient vessels in their class, with consumption and emission figures far superior to any existing heavy-lift vessel today.”