A massive 2.7 megawatt-hour lithium polymer battery system from Canada's Richmond BC-based Corvus Energy is capable of powering the 14,500-tonne Scandlines ferry Prinsesse Benedikte, with its 300 cars and 900 passengers for up to half-an-hour on its 20 km run between Rodbyhavn, Denmark and Puttgarden, Germany; but that’s not the main reason for the retrofit installation announced by the companies at the recent commissioning.

Ferry 'Prinsesse Benedikte': Photo credit Scandlines

A best of both worlds kind of solution, Fini Hansen, Technical Superintendent, Fleet Management, Scandlines Danmark A/S explained: “Scandlines is making a significant investment in new green technology that will benefit the people in the areas adjacent to the harbour and beyond in terms of reduced pollution. Corvus batteries are used primarily to minimize diesel engines running at non-optimal load. Further, this means load-leveling function in order to keep a high level of fuel efficiency and reduced number of generating sets in service.”

Lithium Polymer Battery Bank: Photo credit Corvus Energy

Research quoted by Corvus reveals that this type of specialised ferry in service throughout the day, has heavy power requirements on passage, and then idles at the dock for the entire time it is loading and off-loading at the ferry berth. In one example it came out that load and unload time, spent idling at very low genset efficiency equated to 38.5% of daily operational time. On top of that, a typical ferry might spend up to 10% of the time executing low-speed manoeuvres when docking and undocking, also at low diesel engine efficiency.

Puttgarden Ferry Terminal Berth: Photo courtesy of Scandlines

The Prinsesse Benedikte ferry refit involved the conversion of the former diesel electric ferry to a hybrid vessel with Corvus’ AT6500 power modules, using a systems integration system from Siemens, which is designed to estimate the vessel’s power needs and to consider the battery-bank as a source before starting up an additional generator and bringing it online. By such means the hybrid system is claimed to:

• provide enhanced technical reliability and efficiency
• improve maintenance costs
• consume less fuel
• deliver significantly reduced greenhouse gas emissions
• be noise-free
• charge in 30 minutes by renewable, shore or generator power

Corvus Energy’s CEO Brent Perry attended the commissioning together with Scandlines executives and staff and has the last word: "This commissioning is a significant milestone for Corvus because it represents the world’s largest ever hybrid propulsion marine battery pack and an important early success in the marine version of sustainable capitalism. We are honoured to participate and look forward to using this conversion as a template to develop future customer-based solutions for more ferry fleets around the world.”

DP systems have become increasingly complex in their configurations and in their operation aince they were introduced some 50 years ago; sensors have become more sophisticated, there are more of them and the same level of increased complexity applies to the electrical and propulsion systems. GE Power Conversion decided to simplify things and save fuel on occasion, with their new DP control station.

The computer control at the heart of a ship’s positioning system has also become more sophisticated, but the basic principle of DP remains the same: to hold position with a computer system that takes signals from a range of sensors to sense environment, heading, position and attitude and then issues commands to thrusters and propellers. Overall, it is in charge of the complex processes of maintaining a ship on station, a process that needs a high level of system automation so that a single operator can manage the vessel.

New DP Control Station: Image credit GE Power Conversion

Introducing their new control system, GE make it possible for the DP operator to be able to focus on his real job: controlling the ship without being distracted by manipulating and controlling a complex computer system which GE has achieved with their completely new human-machine interface (HMI).

The control panel is very clean and uncluttered with very few control devices. Its 26-inch touch-screen can be tilted to suit each operator’s preference for standing or sitting in front of the screen, or moving around it. It accommodates operators of different heights and is equally visible in a whole range of lighting conditions on the bridge, especially reflections from the sun and artificial light.

The system includes a new ‘Energy-Efficiency’ mode, which can be used when appropriate. For example, when a supply vessel is alongside a rig, what the captain wants above all else is high-accuracy positioning. But if the same supply vessel is standing by at a significant distance off the rig, the new ‘Energy-Efficiency’ mode DP can be engaged, resulting in a greater degree of position accuracy tolerance with substantially reduced fuel consumption.

Inovelis™ Podded Thruster: Image credit GE Power Conversion

Studies have shown that fuel saving may be as much as 10 percent or more with an associated NOx reduction of as much as 20 percent, depending on environmental factors and exact operational profile.  Additionally, if fitted in conjunction with GE’s new compact Inovelis™ podded thruster, which is based on pump jet principles, the manufacturers estimate that a platform support vessel driven by two 2.5-magawatt pods would deliver even greater fuel savings.

The new Inovelis azimuth pod features fixed stator vanes and a nozzle that act together to guide the water flow across the impeller blades, substantially enhancing propulsion efficiency. Its compactness enables an even greater degree of integration between the hull and the propulsion unit, further influencing the ships’ fuel economy and emissions.

A diesel-electric hybrid power and propulsion contract for an unusual catamaran dive support vessel (DSV) has been won by Canada-based Aspin Kemp & Associates (AKA) who solved the owner’s quest for a system that would operate at peak efficiency while ensuring that safety and redundancy measures were in place.  Australia’s Bhagwan Marine’s 56-m DSV was designed by Incat Crowther, also in Australia, and is to be built at the Keppel Singmarine shipyard in Singapore.

Multi-purpose Dive Support Vesse: Image courtesy of Incat Crowther

Now, here’s a Swiss Army knife of an offshore vessel if ever there was one, designed from the keel up to perform six key roles: dive support, geophysical survey, geotechnical survey, cargo transport, hyperbaric rescue and safety standby. Such varied roles demand a multitude of propulsion responses, including liberal idle times while under way, and AKA’s ‘Duty-cycle analysis’ with its XeroPoint Hybrid system seemed to provide the best answer to the puzzle.

Duty-cycle Analysis & XeroPoint Hybrid System
Vessels like this multi-purpose DSP have a duty cycle profile with extended periods of low to medium power requirements and are great candidates for the hybrid system as diesel engines are least efficient at these load levels.

Duty cycle analysis involves finding the most frequent load points (Xero Points) in a vessel's operational profile and designing specific power plant configurations around these points. The conventional propulsion design approach has been to optimise around a single load point at or near maximum power. The illustration below shows both conventional and hybrid design points.

Duty-cycle Analysis: Sketch courtesy of AKA

The XeroPoint Hybrid system integrates electrical and mechanical devices onboard a vessel to provide optimal modes of operation for power and propulsion. The hybrid system’s energy management system strives to eliminate the unnecessary idling of diesel engines by determining the most efficient configuration of the electrical and mechanical devices onboard at any given time.

The hybrid system, which includes a back-up battery bank from Corvus Energy, is managed by AKA’s energy management system (EMS) to give the high level of flexibility of operation Bhagwan had been seeking.

The diesel-electric propulsion system is designed for several customised modes of operation on the DSV, including two ‘Dynamic Positioning’ modes as well as an ‘Emergency Egress’ mode which permits all machinery to be shut down and low speed propulsion and critical hotel loads to be supported by the battery bank.

Dive Support
Designers Incat Crowther say that unlike any other vessel of its size and type, this one will have all dive equipment designed and built in from the outset. A dedicated dive control room will be fitted with a pair of decompression chambers, with a hull compartment directly below dedicated to support equipment such as compressors and dive gas storage tanks. A pair of diver launch and recovery systems is to be fitted to starboard side, whilst a separate launch and recovery system is to be fitted to port for ROV operations. The vessel will also have the capacity to launch, retrieve and store a hyperbaric lifeboat.

The new catamaran DSV will be built under ABS  class supervision  with the notifications ABS +A1, ⓔOffshore Support Vessel (DSV AIR, SPS, FFV1I) +AMS +ACCU, +DPS-2, GP, ENVIRO, RRDA, which reflect the multiplicity of its intended offshore roles.

Design of an icebreaker Offshore Service Vessel (OSV) of 80-m in length might seems a fair step up from a 30-m harbour tugboat, but all in a day’s work for Robert Allan’s Vancouver-based versatile naval architects, who have just been awarded a contract for two new designs for such vessels to be built in Turkey for operation in the shallow, seasonally ice-bound waters of the Caspian Sea.

TundRA 8000 OSV Preliminary Design: Image courtesy of Robert Allan

Robert Allan Ltd. is an independent, privately owned firm of Consulting Naval Architects founded in 1930 when Robert Allan commenced private practice as a Consulting Naval Architect. Year on year, just like Topsy the business grew and grew until in 2008 the company was restructured to a culture of employee ownership with eleven of Robert Allan Ltd.'s core group of senior employees becoming shareholders in the firm. But a present generation Allan – Robert G. – grandson of the founder, remains Executive Chairman and is still actively involved in day-to-day operations of the company which is now a leader in commercial specialised craft design.

In the meantime, the Robert Allan AVT 3000-class Voith Schneider tugboat Cabo de la Vela has arrived in Columbia after the long delivery voyage from the Uzmar Tug and Work Boat Factory in Izmit, also in Turkey.

This tugboat is the second of a two boat order from Carbones del Cerrejón and she will join her sister Media Luna for operations in Columbia’s Puerto de Bolivar, one of the largest coal loading ports in South America, where with a 60-tonne bollard pull, the pair will be the most powerful tugs on station.

Tugboat 'Cabo de la Vela': Photo credit Robert Allan

The 30.75-m  Cabo de la Vela, like most power-packed tugs of this type has a relatively deep draft of 6.2-m, and is equipped with a pair of General Electric 12V228 diesel engines, each rated 2289 KW at 1050 rpm, with each unit driving a Voith Schneider 30R5-250 cycloidal propeller for tight manoeuvring.

The well-proven GE V228 engines are high-compression, four-stroke, medium-speed, turbocharged, electronically fuel injected, class-approved engines designed and built for rigorous marine applications; according to GE capable of operating cost-effectively for more than 20 years. Most components can go without overhaul for up to 40,000 hours on a typical marine duty cycle. This engine delivers economic fuel and lube oil consumption with exhaust gas emissions in compliance with MARPOL Annex VI and U.S. EPA Marine Tier 1 and Tier 2 requirements.

General Electric 12V228 Diesel Engine: Image courtesy of General Electric

The electrical plant comprises two identical Caterpillar C 6.6 ACERT diesel gensets, each with a power output of 125 ekW, 60 Hz, 480V, and Caterpillar have also supplied a 546 KW @ 1800 RPM Caterpillar C18 ACERT auxiliary diesel engine to drive a Fire Fighting Systems SFP 250x350 XP horizontal centrifugal pump.

On deck, winch hydraulics are powered off the front of the FIFI pump engine with a back-up electro-hydraulic pump-set for emergency use and maintenance. The aft deck machinery includes a Rolls Royce ATWH 1500/200 render-recover hawser/towing winch with horizontal warping head, and on the foredeck is a Rolls Royce AW20.5U2H anchor windlass with two cable lifters and two horizontal warping heads.

On trials the Cabo de la Vela met or exceeded all performance expectations including a free-running speed of 13.1 knots. Now Robert Allan’s naval architects turn their attention to the design of those icebreaking OSV’s.

Waste heat from auxiliary marine diesel engines had not been considered much worth thinking about in the past, but times change; a significant amount of energy can now be utilised from the auxiliaries to supplement steam requirements during port stays, and also for some vessels during voyage. With high bunker prices and in challenging economic times for the shipping industry as a whole every single saved dollar counts: witness United Arab Shipping’s recent decision to retrofit all forty-eight ships in its fleet with the latest Alfa Laval Aalborg XS-TC7A auxiliary engine waste heat recovery systems.

Container Ship 'Umm Salal': Photo courtesy of United Arab Shipping Company

With its small footprint and the lowest possible weight to output ratio, the Aalborg XS-TC7A economiser optimises the use of waste heat from the auxiliary engine exhaust gases during voyage and port stays. When used in combination with a waste heat recovery system installed after the main engine, the Aalborg XS-TC7A contributes to significant reductions in oil consumption on the oil-fired boiler under most load conditions. Each unit being specially tailored to the individual ship and engine design taking into consideration the existing uptake back-pressure and other critical factors.

The manufacturers say that their Waste Heat Recovery (WHR) concept has been developed as a customised solution with special focus on energy generation compared to return on investment. They envisage a very short payback time of around to 4-6 months in optimum cases, but normal payback time is calculated to be nearer a year to 18 months, depending on the number of days the produced steam can be utilised (offset against the steam requirement from the oil fired boiler) and whatever redundancy arrangements are required.

Waste Heat Recovery System Schematic: Image courtesy of Alfa Laval

Alfa Laval list these features of its auxiliary engine WHR system:

• Able to supply or support the steam demand during port stay
• Cost of steam production (energy) is nearly free
• Financially sound investment with very short payback time
• Adds a “green” profile to the ship
• Lower emission tax (if introduced)
• Less maintenance and lower operating costs for the oil-fired boiler

 “This order confirms the ship owners’ increased focus on environmental protection and interest in realizing fuel cost savings from smart solutions using the available waste heat onboard,” says Hans-Henrik Jensen, Vice President, Marine & Diesel Division, Alfa Laval. “Ship owners know and trust that Aalborg waste heat recovery systems for use after the main engines save money and reduce emissions. We now see a growing tide of ship owners like United Arab Shipping Company interested in capturing waste heat from auxiliary engines and placing their trust in the Aalborg XS-TC7A.”

News in the past week boosted diesel engine manufacturer Wärtsilä's business in the offshore platform supply vessel sector: First a major contract to design and power a series of four multi-purpose platform support vessels (MPSVs) for Malaysian-based international offshore oilfield services provider Bumi Armada Berhad. Then, from the other side of the world, came word that the United States Environmental Protection Agency (EPA) had certified the company’s 34DF engine (soon to be installed in a new series of  Gulf of Mexico US-flag platform support vessels) as emission standard compliant.

Malaysia MPSV Order
Wärtsilä will supply a comprehensive design and propulsion package for each of the four vessels to be built by a subsidiary of Nam Cheong Limited, in one of its subcontracted yards, Fujian Mawei Shipbuilding Ltd, in China.

Platform Supply Vessls WSD 1000 Design: Image credit Wärtsilä

The contract comprises the basic customised design, the main diesel-electric propulsion power generation system, the Wärtsilä Low Loss Concept (LLC)electrical system  (an energy efficient and highly redundant power distribution system for electric propulsion applications) and the automation system.

The WSD 1000 design for the LOA 88.8m (291ft) MPSV’s includes four gensets whose power (in excess of 6MW) is distributed via the LLC system to two Wärtsilä main azimuth steerable thrusters aft, and two tunnel thrusters forward. The design service speed is 15.0 knots.

Wärtsilä 34DF United States EPA certification
The 'Harvey Energy', an offshore supply vessel for New Orleans headquartered Harvey Gulf International Marine, will be the first to have one of these engines; a breakthrough entrance for Wärtsilä into the huge North American offshore market.

"The Wärtsilä 34DF is the first dual-fuel engine fulfilling the EPA requirements and this is a very important statutory recognition of Wärtsilä dual-fuel technology," says Andrea Bochicchio, Director, Product Management & Engineering, Product Centre 4-stroke, Wärtsilä PowerTech.

Dual-fuel Wärtsilä 34DF Marine Diesel Engine: Photo courtesy of Wärtsilä

Wärtsilä announce that four sister vessels will shortly be supplied with the same Wärtsilä engines, thus further demonstrating both the viability of liquefied natural gas (LNG) as a marine fuel and its growing popularity among ship owners and operators. LNG fuelled vessels offer compelling operational cost savings and significant environmental benefits.

The switch to LNG propulsion is part of Harvey Gulf’s ‘Going Green’ initiative, aimed at reducing the environmental impact of the company’s vessels and operations. “These PSVs will be the cleanest burning vessels operating in the Gulf of Mexico,” says Chad Verret, Senior Vice President, Harvey Gulf International Marine.
 

The largest marine diesel engine in MTU’s stable, the 11-ft high, 21-ft long four-stroke 8000-Series has just arrived at Tognum America’s Training Centre in Canton, Michigan, where it will be used for in-depth maintenance and repair courses. An expensive addition – why for?

The reason is that this engine (available in 16V and 20V configurations) has become increasingly popular in commercial marine and defence applications making it clear to Tognum that there was a need for an additon to their US hands-on training facility. Then, last year Tognum further increased the appeal of the engine, upping maximum output of the IMO MARPOL Tier 2 emission compliant 20-cylinder version from 9,100 kW to 10MW.

Littoral Combat Ship USS Independence: Photo credit USN

Engines of this type are being installed in the US Navy’s new class of frigate-sized 416-ft long 44-knot Littoral Combat Ships (LCS). In the Freedom-class LCS variant USS Independence a pair of 8000-Series engines provide power in a diesel and gas turbine (CODAG) main propulsion system combined with two GE LM2500  gas turbines to drive four water-jet pumps.

MTU 8000-Series Engine at Tognum North America Training Center: Photo credit Tognum

At the heart of the 20V 8000-Series success is proven performance coupled with state of the art technology that includes Common Rail Fuel Injection (CR). On this engine, unlike the smaller 4000 Series which has a rigid fuel accumulator (CR) for each row of cylinders, the 8000 Series engine has a separate accumulator for each cylinder located in the vicinity of the injector. This arrangement facilitates a smaller overall engine width and optimum progression of combustion, reducing the interplay between the injectors and the pressure fluctuations in the fuel pumps. By this means only two HP pumps are required to generate the substantial pressure and the necessary flow volume for the entire engine.

MTU 8000-Series CR Accummulator System: Image courtesy of Tognum

“The addition of the Series 8000 to the MTU Training Center enables us to offer Series 8000 training to Navy and Coast Guard personnel, as well as shipbuilders, here in the U.S. for the first time,” said Wolfgang Griener, senior manager, MTU Training Center. “Previously, such training was only available in Germany. Our new Series 8000 training courses will provide our North American customers with the information and hands-on experience they need to keep their equipment performing at optimal levels.”

Since mid-March 2013, Tognum AG has been a wholly-owned subsidiary of Engine Holding GmbH, a joint venture of Daimler AG and Rolls-Royce Group plc.

One of the world’s largest four-cylinder two-stroke marine diesel test engines (the electronically-controlled 4UE-X3 with a bore diameter of 60 cm) has been installed and brought up to speed at MHI, Mitsubishi Heavy Industries’ Nagasaki Research & Development Centre, where it thumps away producing data the Japanese marine engine manufacture needs to keep up with the leaders in a highly competitive business. MHI claims it is the only licensor among the top three in the world to carry out all of its own engine development, design and manufacturing.

Marine Diesel Engine Test Plant MHI 4UE-X3: Photo courtesy of MHI

Test Engine Features

• Main body structure: The main body (bed plate and column) uses a high rigidity, light-weight and simple single wall structure for simplicity of manufacture. The structure and thickness of the wall is optimized through FEM analysis using 3D modeling, etc.
• Combustion chambers: Bore cooled, high top land pistons are used to deal with the high heat load. The cylinder liners employ a new construction with reinforced rings.
• Bearings: The main and crankpin bearings are aluminium bearings instead of conventional white metal bearings.
• Electronic control: Full electronic control is employed, in line with the compact and reliable Eco system used on the latest commercial engines.
• Lubricating system: The latest A-ECL system, which can reduce lubricating rate, is used as the cylinder lubricating system.
• Test plant control: Remote control and alarm systems are installed in order to simulate actual operation on a ship. In addition, MHI's DIASYS Netmation® control system was used for the integrated control of auxiliary machines and ancillary facilities

The company is focusing its R&D attention on the slow-speed diesel, the workhorse engine of choice for the majority of the 50,000 or so large merchant ships that continually ply the oceans in global trade. Engine of choice by shipowners, it normally burns heavy C bunker oil, the cheapest dregs of oil in the refining process, but nevertheless it is also energy efficient. As a sole propulsion engine, it achieves thermal efficiency as high as about 50% with a directly coupled slow propeller shaft rotational speed of about 100 rpm.


Engine Control & Measurement: Photo courtesy of MHI

The test engine is being used not only to verify the performance and reliability of the latest engine technologies, but also to develop engines capable of operating on different kinds of fuel (gaseous fuels, like LNG in particular) so as to comply with increasingly stringent engine exhaust gas emission regulations. For example, with this in mind, an EGR (Exhaust Gas Recycling) system, has been tested already and the NOx reduction effect ascertained.

MHI plans eventually to bring the  4UE-X3  engine to the market after its performance has been fully optimised.

Source: Mitsubishi Heavy Industries Technical Review Vol. 50 No. 1 (March 2013).

Overhaul cylinder heads and liners; pistons and con rods; cam shafts; bearings; vibration dampers and injectors, and two turbocharger units after completely dismantling three of the marine diesel engines that power Dive Support Vessel (DSV) Rockwater 1, and get it all done within 18 days.  That would be a tall order for many firms in the engine service support business, but Royston’s nine-man team of engineers based in Newcastle-on-Tyne, in the North-East of England, worked day-and-night shifts without missing a beat to complete this first stage of the vessel’s 30,000-hour engine overhaul so that the  Subsea 7 offshore vessel was back to work on time after scheduled docking.

Photo courtesy of Royston Ltd.

While the team beavered away aboard the DSV in the Barrow-in-Furness dock, another six engineers machined components in the company’s nearby Newcastle workshop, a job that included servicing 27 cylinder heads and liners; fuel injectors; and a complete overhaul of two turbochargers.

The 98-m LOA, 4,905 gt Rockwater 1, features a single-bell saturation dive system, and is powered by a diesel-electric propulsion system consisting of five 1,700 kW Brons-MAN ASL25/30 diesel engines that each drive a 2125 kVA NEBB WAB 630 generator which produces power for two 1,800 kW azimuth thrusters and three 7,90 kW tunnel thrusters.  Because the diesel engines are used to power generators the Rockwater 1’s engineering staff will be able to vary their running hours and control the service intervals; this way the Royston team will be able to overhaul the remaining two engines during the ship’s next planned maintenance period.

DSV Rockwater 1: Photo courtesy of Subsea 7

P&O Australian Contract
Royston is a firm with a global reach, having facilities in Perth, Western Australia where the ‘Down-Under’ team earlier completed a major three-week 60,000-hour diesel engine overhaul contract with P&O for work on the P&O Southern Supporter while she was berthed not far way in Henderson’s Fremantle dock.

The P&O Southern Supporter has an Ice Class 1A rating and is well-known in the Southern Ocean where she has been operating extensively since launch in 1993.  The 74-m vessel is equipped with an A-frame and crane which enables her to perform a wide variety of survey, maintenance and supply tasks.  Engine performance and reliability are critical for a ship that has been used to take equipment and personnel into Antarctica.

On this job, again time was of the essence, and the project called on the eight-man Royston team to work continuously around the clock to service and re-build the ship’s three Cat 3516 engines. This included a complete strip-down of the engines, replacing the main bearings, overhauling the cylinder heads, upgrading liners with spacer-plate modifications. The work also included camshaft grinding on one of the engines and the overhaul of all ancillary components.

Royston has been in business for thirty years providing fleet maintenance service for all types of seagoing vessels and for diesel engines on offshore platforms or ashore. They say that their technicians come from a variety of OEM backgrounds and maintain their skills at the highest levels to ensure that even discontinued products can remain fully operational.

Cylinder liners of both 4-stroke and 2-stroke engines show signs of wear and tear after extended use, regardless of the latest advances in lubricating oil and liner casting technologies. What's not quite so obvious is that when doing the consequent engine overhauls or engine repairs that involve cylinders, it is predictable that the liners will have to be deglazed and crosshatched. For cylinder deglazing jobs (plateauing as well) one industry standard tool is the compact, portable ball hone from Brush Research Manufacturing (BRM), who recently announced that its Flex-Hone® tool was available for ‘big bore’ marine diesel engines up to 40-inches in diameter.

'Big Bore' Cylinder Liner: Photo courtesy of Bright Hub Engineering

When a cylinder liner comes out of the factory, it will have a slight cross-hatch pattern honed into its surface, an increased roughness to help the liner surface to retain the lubricating oil needed to provide an evenly distributed oil film between the piston ring reversal points. If the surface becomes too smooth due to wear with glazing of the surface, the piston rings will more easily break the oil film, causing even more wear. Worse still, any excess oil will no longer be retained by the liner surface, and will burn off instead, causing an increase in lube oil consumption.

The BRM Tool
Widely known by its Flex-Hone® brand name®, the ball-style hone is a highly specialised abrasive tool that is instantly recognisable by its unique appearance. Featuring small, abrasive globules that are permanently mounted to flexible filaments, the product is a flexible, low-cost tool that is a favourite among mechanics and metal workers due to its cylinder deglazing, de-burring, edge blending and crosshatching capabilities.

Flex-Hone® tool: Image credit BRM

An Inexpensive Alternative to Air-Operated Equipment
The electrically operated flexible hone is an efficient alternative to air-operated equipment which must be lined up with the studs on the engine block. Not only does the ball hone set up much more quickly, but just a few passes up and down inside a cylinder liner accomplishes thorough deglazing as well as crosshatching. The Flex-Hone® tool's independently-suspended, abrasive globules both self-centre and self-align to the bore as well as compensate for wear, all of which facilitate close-tolerance finishing work.

Plateau Finishing for Piston Ring Seating
Wear on the liner is not evenly distributed – most of it occurs between the reversal points of the upper and lower piston rings –  and commonly scuffing marks are to be seen where the upper piston ring changes direction. The purpose of plateauing is to remove loose, cut, torn and folded material within the cylinder, create valleys and remove peaks that would otherwise damage rings or seals, and the Flex-Hone® is capable of that as well.

Although the Flex-Hone® is used for refurbishing cylinder liners, BRM (factory located in Los Angeles, California) say the tool is also quite versatile and adaptable to many applications where honing the inside of cylindrical shapes is needed, including cleaning pipe bores and valves on some pump designs.