Monitoring machinery and vibration using condition-based and predictive maintenance can stop issues becoming problems
Information from engineroom equipment and propulsors enables operators to implement condition-based or predictive maintenance strategies and remotely manage vessel performance. Monitoring tug propulsion systems can reduce the risk of mechanical failures, improve performance and reduce noise and vibration.
Operators can use digital tools to transform tug maintenance and minimise downtime from machinery issues, improving transparency, reducing operational expenses, raising productivity and increasing flexibility, says SKF service sales manager Gavin Coull. “The ability to perform tasks remotely, digitally with less touch points, has many advantages,” he adds. “Continuous online monitoring is becoming more scalable and valuable every day.”
Swedish monitoring equipment supplier SKF has developed a portfolio of digital tools enabling remote maintenance to support marine operations. Its Enlight Centre is a unified data hub for predictive maintenance that collects data from sensors and systems for analysis, displaying the information in a dashboard that can be accessed by a chief engineer, superintendent, fleet manager or even by a class surveyor or an SKF remote diagnostic expert.
SKF has also invested in artificial intelligence and digital technology to generate easily digestible insights on equipment health.
When applied to rotating equipment, Mr Coull says advanced analytics and software can be used to “turn data into decisions and actionable insights” for crew on vessels.
US-based precision alignment and vibration analysis firm AME Solutions technical projects manager Tony Planamento says the Covid 19 pandemic has driven more operators to use remote monitoring and analysis.
He says Covid 19 has “forced the industry to start thinking outside of the box and come up with some creative solutions.” Companies are transferring more engineroom data for condition monitoring through wireless sensors, Bluetooth gateways and connectivity to cloud resources.
This data can be displayed on board for crew to act upon and ashore for managers to make better decisions. Mr Planamento says this can be applied to vibration data to monitor equipment wear.
With conditioning-monitoring systems, if there is an issue with machinery, an alarm sounds. Technicians can “log in, analyse the spectrum, data, and figure out what is causing that alarm,” says Mr Planamento. “Some of these systems are pretty sophisticated in that they can trigger work orders to go and investigate this data as well. And that can help operators drill down to the root cause.”
AME Solutions regional manager Rich Merhige explains how to discover the cause of potentially damaging vibrations.
“Through vibration analysis, we can identify root causes and mechanical faults,” he says. This can be achieved through analysing established patterns and converting oscillations to their frequency domain, examining harmonics and splitting different noises into their related frequencies and amplitudes.
“Due to mechanical creep and misalignment, there will be more noise,” says Mr Merhige. “It is important to maintain engine mounts, but we have seen this can be neglected.” He recommends tug operators examine isolating mounts and ensure they are maintained.
Vibrations come from mass unbalance, misalignment, gear tooth wear and propeller cavitation. Linear vibration is split into vertical, horizontal and axial through analysis. Torsional vibration comes from changes in angular velocity and can be identified through rotational vibration analysis.
If these are identified, tug owners can carry out precision alignment, dynamic balancing and change structural resonance to more natural frequencies to minimise harmful noise and vibration.
There are regulatory requirements covering noise and vibration. The European Commission’s directive 2008/56/EC includes human-induced underwater noise in the definition of pollution and IMO’s adoption in SOLAS requires vessel construction to reduce onboard noise.
Other rules and regulations include IMO’s Marine Environment Protection Committee-approved guidelines focused on reducing underwater noise to mitigate any negative impact on marine life and DNV’s silent class notation.
“There is more awareness about vibration and noise limits on vessels,” says Mr Merhige. “IMO has adopted rules to reduce vessel noise and vibrations. It is increasingly important to consider noise, vibration and machinery alignment, and to make sure machinery is operating properly,” he says.
Geislinger Gesilco & Acoustics director Christof Sigle says there are several methods of reducing both vibration and noise.
“Reducing vibration is key to reducing engine and powertrain noise,” says Mr Sigle. “Highly integrated solutions save weight and installation space,” he says.
Geislinger’s solutions for acoustically optimised drivetrain applications include reducing torsional vibrations through acoustically optimised steel-spring couplings. With these compact and high-power density couplings, stiffness and damping can be adjusted to customer requirements.
Geislinger’s Silenco acoustic coupling combination reduces sound transmission and optimises acoustic attenuation with maximised transmission loss. They are lightweight, maintenance-free and have the lowest reaction force.
However, there are challenges as vessel owners adopt hybrid propulsion and dual-fuel engine types. “New engines have higher firing pressures, so it becomes more challenging to manage vibrations,” says Mr Sigle.
Vibration and noise can be minimised through design. “It is important to find the best solutions to reduce sound in systems,” says Mr Sigle. “We want to get in at the beginning of projects to find optimal solutions for these applications.”
West P&I global head of loss prevention Simon Hodgkinson agrees developments in digitalisation, ship modelling and predictive maintenance are the future. “These are the first few steps of the journey,” he says.
“It will be great to see the next generation of smarter ships. This will happen in the future, but too many owners are sitting on the sidelines.”
Insurers are interested in technology developments and could be willing to reduce premiums for owners who demonstrate how these processes result in higher safety and lower risk.
“Smart maintenance can add real value, especially from a loss prevention perspective,” Mr Hodgkinson says. “We want our members’ vessels to be maintained in good condition as this reduces the risk of an incident.”
Condition monitoring and predictive maintenance provide “great early warnings for potential issues”. But there are practicalities that need to be considered.
“It must be used in conjunction with proper crew training and operational and maintenance checks in line with manufacturer advice and best practice,” says Mr Hodgkinson. “There is a high cost to installing sensors on board and a cost to operate shore analysis.”
Planned maintenance kits unveiled to improve efficiency
Caterpillar Marine has introduced planned maintenance kits for all its propulsion engines and generator sets up to, and including, C7.1 to improve servicing efficiency.
It says these packages are a “fast, convenient, and affordable way for customers to ensure they have all the Cat parts they need, when they need them, for key service intervals.”
These planned maintenance kits are for Cat C1.5-C7.1 products and are pre-configured with all the parts required to carry out regular maintenance for Cat propulsion engines and genset models over the lifetime of the asset in 2,000-4,000-hour cycles.
“By introducing the new planned maintenance kits, we are empowering customers with another way to ensure maximum uptime and realise optimum performance and reliability for their propulsion engine or genset,” says Caterpillar Marine global commercial manager David Surroca.
“The kits will contain everything customers need for their service interval except fluids, which can be obtained from their Cat dealer,” he adds.
Two kits are required to complete the maintenance: a base kit and a filter kit. Each kit is tailored to specific engine requirements such as cooling systems, simplex or duplex filter arrangements.
Houston, Texas-headquartered Caterpillar Marine says its three-step process makes it easy to determine the appropriate kit for the engines and gensets.
Once a kit has been used, customers can order another kit to prepare for the next cycle of scheduled maintenance. Customers can also acquire kits when purchasing a new engine or genset through a Cat dealer.
Caterpillar Marine provides medium- and high-speed engines with outputs from 93 to 16,800 kW and gensets from 10 to 16,100 ekW.
Manufacturers innovate for tug fleet propulsion
Azimuth propulsion suppliers will incorporate electrical and hybrid innovations into their thrusters for new fleets of harbour and escort tugs to reduce fuel consumption and emissions, but improve bollard pull and manoeuvring for these newbuild tugboats.
Schottel will include hybrid-mechanical drives into rudderpropellers it is supplying for a fleet of escort tugs under construction in Brazil.
This follows a contract to supply thrusters for four azimuth stern drive (ASD) tugs Starnav intends to build at its Detroit shipyard in Itajaí. The first of the four 32-m escort tugs is scheduled to enter service in 2022.
Schottel will supply SRP 490 nozzle thrusters, each rated at 2,525 kW featuring fixed-pitch propellers with a diameter of 2.8 m.
With this thruster configuration and two diesel-driven main engines, these ASD tugs will achieve more than 80 tonnes of bollard pull and a maximum speed of 12.5 knots.
Rudderpropellers on the first tug will feature Schottel’s patented Sydrive-M technology from the start while the other three will be configured to be Sydrive-ready.
Sydrive is a mechanical-hybrid drive system without the costly complexity of common hybrid technology, to help lower maintenance costs and fuel consumption.
“By using Schottel’s hybrid solution, we seek clean operations. Starting now is particularly important: the vessels built today will be in the water for decades to come,” says Starnav chief executive Carlos Eduardo Pereira.
“Our focus has always been the high level of reliability in the equipment, mainly safety and environment care,” he explains. “With 34 vessels propelled by Schottel in our fleet, we will continue expanding our operations and benefit from a strong partner with extensive know-how in Brazil.”
Sydrive-M connects a port and starboard-mounted azimuth thruster in one vessel, allowing the thrusters to be driven together by only one of the main engines.
The system needs no additional electronic components, which offers many advantages as demonstrated in three main operation modes: light operation or free sailing mode, full thrust operation mode and FiFi mode.
This configuration helps reduce the operating hours of the main engines, resulting in lower maintenance costs and reduced carbon emissions.
Steerprop has re-entered the tug market with an order for six Z-drive azimuth propulsion units, each with electrical steering.
These are for three harbour tugs Uzmar is building in Turkey to Robert Allan Ltd’s RAmparts 2300 UZM design. Each of these tugs will have two SP 20 WD azimuth propulsion units, each delivering 1,610 kW of power.
Steerprop sales manager Donato Agostinelli says these Z-drives were delivered during Q3 2021.
“Since the tugs will be operating in challenging conditions and performing very different tasks throughout their life, the propulsion units must be efficient and reliable under all circumstances,” he adds. “For these reasons, the units also come with our condition monitoring system as standard.”
The azimuth propulsors have electrical steering to increase the achieved bollard pull to 50 tonnes for these 23-m tugs. Electrical steering improves the manoeuvrability of the tugboat enabling more efficient use of the main engine’s power compared with hydraulic steering.
“The agile electrical steering system in our Z-drive azimuth propulsion increases overall performance and reduces the running costs of the vessels,” says Mr Agostinelli.
“The electrical system can also be upgraded with a battery pack to enhance performance even further, while at the same time lowering the environmental footprint of the system.”
Electric steering gears offer a constant steering speed, which is important when performing sensitive tasks such as escorting tankers.
“Since the steering uses power only when actively turning, it is very energy-efficient,” Mr Agostinelli continues. “In addition, the electrical steering also produces significantly less noise than hydraulic steering systems and requires little service due to its mechanically simple construction.”
Mr Agostinelli says this award will enable Steerprop to gain more contracts in the tugboat propulsion market. “This is a great reference to make a re-entry in a segment that is not new to us, but in which we have not been present for a while,” he says.
Steerprop’s W Series is a modular and scalable propulsion line with a power range from 900 to 7,000 kW. Propulsion units can have open or ducted propellers and can be delivered with a Z-drive or L-drive configuration. They comply with the rules of all major classification societies.