Q&A with Eagle Marine Group: Smart Propulsion Systems

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Marine Log (ML): What is EGM Propulsion introducing to the commercial marine propulsion market with its modular propeller system?

Wayne Wingate (WW): EGM (Eagle Marine Group) is a new division of Fundilusa that has combined its foundry’s experience of manufacturing propellers and propulsion components since 1989 with today’s leading-edge technology and development of new patents. Our new modular propeller system, called Smart Propulsion Systems (SPS), is an adaptation of a concept with deep roots in the marine industry dating back to the mid-19^th century and more recently applied to Ice breakers, Navy vessels, and Cruise ships. SPS brings this technology to the commercial sector by standardizing components and tailoring to the existing shaftlines that are most used in this market segment. This allows for direct replacement of monoblock propellers without modification to the shaft. We can also develop unique custom solutions for specific applications. The goal is to bring the benefits of a modular propeller system to a larger audience much like in the computing world when PCs were first introduced in the day of MAINFRAME computers.

ML: How does the modular “build-up” propeller design differ from traditional monoblock propellers and CPP systems?

WW: It might be better to ask how SPS is similar to monoblock propellers and CPP (Controllable Pitch Propellers) systems. From appearance and performance, any FPP (Fixed Pitch Propellers) monoblock propeller can be made as a SPS propeller. If you were to see a boat in drydock with SPS propellers, you would not be able to differentiate from a monoblock propeller unless you got close enough to inspect the hub and see a bolt pattern. In comparing SPS to CPP propeller systems, obviously they both bolt the blades to a hub. In the case of SPS, the hub is same size as a monoblock propeller and smaller in comparison to the CPP hub since there is no need for a mechanism to rotate the blades. The SPS is much more robust than CPP since they are attached to a solid hub versus the rotating palm in a CPP hub.

ML: What maintenance and durability benefits does a hub-and-bolted-blade configuration provide operators?

WW: One of the key benefits of SPS has to do with the installation and removal of the propeller. With tugs and towboats working in such harsh environments, the operators want to ensure the propellers are properly fitted such that there is no risk of losing the propeller. One common practice has been heating the hub for both installation and removal. Unfortunately, this severely damages the propeller over time and results in spider cracks on the hub. The USCG (United States Coast Guard) is now becoming more critical of this practice and condemning propellers. The benefit with SPS is the installation of the hub utilizing a hydraulic push-up nut to properly secure without the use of heat (NOTE: Using a hydraulic push-up nut does not mean the hub is a hydraulic hub. EGM does offer hydraulic hubs with SPS as an option). Once the hub is installed, the blades can be easily installed/removed for repair or replacement without having to remove the hub. The blades are bolted in place with a specified torque value determined by our engineers to meet the strength requirements per ABS (American Bureau of Shipping) rules. The hydraulic push-up nut also has calculated pressure values that meet ABS rules for hub/shaft taper fit. This gives the operators the peace of mind knowing measurable engineered values that meet ABS rules are used to install the hub and blades. Subsequently, the USCG defers to ABS rules for propellers, so the operator can have confidence in both the design and installation of the SPS propeller.

ML: How can modular blades help vessels reduce downtime and manage spare parts strategy?

WW: Reduced down time is the fastest way to realize your ROI (Return on Investment) with SPS. A haul-out to repair a damaged propeller can be reduced to just one day and have no risk of damaging the hub due to heating and potentially prematurely putting the vessel back in the water before letting the propeller properly cool after installation. Additionally, severe propeller damage is commonly limited to one or two blades. A vessel could travel with spare blades on board and replace the blades with the vessel in the water, making for an even faster turnaround and no need to find a dry dock. If there is a fleet of vessels needing the same propeller, spare blades can be housed in a warehouse and rapidly deployed to the vessel in need. SPS allows for a scalable solution and flexibility within the fleet. The modular hub can remain with the shaft and blade design can change to suit the needs of a season or different operating points. There is also a trade in program for NiBrAl blades as credit towards new blades. As popularity grows, a used market will grow since the hubs are standardized.

ML: What manufacturing, lead time, and shipping advantages does this propeller design offer, particularly for large diameters?

WW: Large diameter monoblock propellers present a variety of challenges when it comes to manufacturing and shipping logistics. Fundilusa is no stranger to producing monoblock propellers up to 5.5 meters (18 feet) and 15 tons and know what is required to maintain a quality casting and meeting tolerance specifications. This is why they see a great future with manufacturing a modular propeller system. When making the modular propeller, the casting is done in several parts: the hub and the blades. Smaller castings are easier to control the homogeneous properties and ensure a consistent high-quality casting. Additionally, these individual components are easier to handle, and CNC (Computer Numerical Control) machining tools heads have full access to 100% of the surface, whereas monoblock propellers will have areas that are not accessible. Hence, SPS are 100% fully CNC. This allows for repeatability and the most accurate components both dimensionally and with material properties.

Given the manufacturing process of the individual components, it also means that several CNC machines can be working on the same propeller simultaneously greatly reducing lead times.

Shipping logistics for large diameter propellers that are “out of gage” when it comes to both ocean freight and ground transport can be quite challenging. Flat rack and open top containers have limited space on ships and typically lead to delays and have higher premiums. Ground transportation is equally challenging requiring escorts, limited routes, time of travel and potential height restrictions. SPS propellers ship disassembled and can fit within a container eliminating the hassle, extra costs, and delays.

In the event that one of these large diameter propellers is damaged and propeller repair services are not available, spare blades can be rapidly cast, machined, and loaded in a container in weeks, not months. It is for this very fact ice breakers, Navy vessels, and cruise ships chose a modular propeller system. And now so can the commercial fleet!