Optimized Reliability from Steerprop – the Azimuth Propulsion Company.
The goal of the Finnish company Steerprop Ltd. is to provide the global maritime market with azimuth propulsors of exceptional quality and reliability. Up to now CRP (contra-rotating propellers) azimuth propulsors have been limited to smaller vessels. With enhanced efficiency, however, they can now be used in larger and faster vessels than before. Recently Steerprop has introduced its latest development of CRP Propulsors up to 20.000 kW with enhanced efficiency.
One high-efficiency propulsion solution is the dual-end CRP azimuth propulsor. Its propulsive load is divided between two gear wheels with both a pushing and a pulling propeller. These larger and slower propellers, whose efficiency is further enhanced by the positive hydrodynamic effects of the propulsor body, offer a 5 – 20% improvement in propulsive efficiency even – and especially – at higher speeds while maintaining the outstanding manoeuvrability inherent in azimuth propulsors.
The company has delivered dual-end CRP propulsors to a number of vessels with different operational profiles worldwide, in particular to platform supply vessels (PSVs) and survey vessels operating in the challenging conditions of Norwegian oil fields. Based on the experience with these vessels, Steerprop is conducting research and development to bring CRP technology to propulsors with up to 20 MW in power at speeds of 25(+) knots, and to high-powered propulsors for the most demanding Arctic ice classes.
The new Steerprop SP ECO CRP propulsor with up to 20.000kW
Hannu Jukola, a Steerprop naval architect specializing in hydrodynamics, said: "With the new ECO CRP, we are able to combine a demanding ice class with high power and a high open water propulsive efficiency. We envision that this would be particularly useful for LNG carriers, cargo vessels and tankers operating on the Northern Sea Route." As a part of the research and development process, the Finns have undertaken several model tests with CRP propulsors having power ratings of 2.5 MW, 6.5 MW, 15 MW and 20 MW, using a variety of propulsion and vessel configurations in both ice basin and open water tests. The ice basin tests showed that the ECO CRP could allay the fear of a block of ice making contact with both propellers simultaneously since the propellers are located several metres apart on different ends of the propulsor's body. This enables the ECO CRP to be built into 20 MW, using a variety of propulsion and vessel configurations in both ice basin and open water tests. The ice basin tests showed that the ECO CRP could allay the fear of a block of ice making contact with both propellers simultaneously since the propellers are located several metres apart on different ends of the propulsors body. This enables the ECO CRP to be built into virtually any ice class - even the most demanding Arctic ones - without fear of damage to the propulsor or main engine by a double propeller ice load. The open water tests verified the propulsors high-speed open water efficiency, while showing how proper steering angles could be used to further enhance the propulsor's efficiency. "The tests verified the predicted benefits of CRP propulsion in a larger-sized propulsor, but they also revealed certain unexpected benefits," Jukola said. "In particular, the different nature of the ECO CRP propulsor's slipstream seems quite promising for ice management. This may enable completely new applications for these propulsors in shipping vessels as well as dedicated ice-management vessels."
PSV Stril Polar equipped with two 3.000kW SP 35 CRP propulsors in DNV ICE-C Ice-class