New engines for the Royal Navy’s Type 23 Frigates

Originally designed with a service life of around 18 years, the RN’s Type 23 Frigates will now have to serve for around 30 years. All 13 frigates are undergoing life extension (LIFEX) refits and an important component of these upgrades is the Power Generation Machinery Upgrade (PGMU) to replace the ships’ four diesel generator sets.

The Type 23 LIFEX programme is being run by the Surface Ship Support Alliance (a partnership between the MoD, Babcock and BAE Systems) and began in June 2015 when HMS Argyll was taken in hand at Devonport. At the time of writing HMS Argyll, Westminster, Montrose, Northumberland and Kent have all completed LIFEX refits. The most obvious external change is the fitting of the CAAM Sea Ceptor missile system to replace the ageing GWS-26 Sea Wolf but the refits also include major changes to equipment, the combat system, chilled water arrangements and work to extend the life of the hull and superstructure. Unfortunately, the first ships to undergo LIFEX have not received new engines and will have to wait until their next major refit. HMS Richmond will be the first ship to receive the machinery upgrade and is currently mid-way through her refit in Devonport and work has also started on HMS Portland and HMS Lancaster. The LIFEX refit of each Type 23 is costing at least £35M per ship, not including the PGMU. Totalling around £600M for this work across the frigate fleet, this is a very necessary and worthwhile investment but could have been much reduced if the Type 26 frigates had been ordered earlier.

The oldest Type 23s HMS Argyll and HMS Lancaster will never receive the PGMU. Assuming they survive future defence cuts, they will have to soldier on with their Paxman diesels until they go out of service in 2023 and 2024 respectively. The project is set to be completed by 2024 when last of the other 11 ships receives its new engines.

The MTU 20V-4000 M53B Diesel Engine (Photo: Rolls Royce)

The first of the new MTU 12V 4000 M53B diesel generator sets were delivered to Devonport Naval Base in late 2016 for fitting to HMS Richmond. The new gensets are manufactured in Germany by MTU (A subsidiary of the Land & Sea division of Rolls-Royce) and provide 1.65MW each. This will provide the ship with approximately 20% increase in available power for onboard weapons, sensors and electronics as well as for cruising propulsion. The old Paxman Valenta 12 RP2000CZ diesel design dates from the 1960s and are becoming increasingly maintenance-intensive. They are rated at 1.3MW but and have reduced power output as low as 1MW in hot climates. The new diesels perform better in hot conditions and will drastically reduce maintenance time and running cost. The MTU 4000 gensets include sophisticated noise reduction and shock resistance measures and are exceptionally reliable. The PGMU project presented a considerable engineering challenge as new equipment had to fit within the existing structural and compartment constraints and integrate with the ship’s services and systems.

The PGMU project comprises 5 separate components (which the DE&S tendered for in ‘lots’); diesel generators, power conversion equipment, electrical switchboards, the machinery control and surveillance system (MCAS) and the integration work. A £68M contract was signed by the DE&S with MTU to supply the 48 generator sets in April 2015. The contract includes a complete logistics package, spare parts and initial training. The RN’s mechanical engineering training establishment, HMS Sultan will receive equipment and electronic manuals so it can provide relevant training for MEs serving on the upgraded Type 23s.

Hitzinger UK won a £12M contract for the voltage converters and Rolls-Royce signed a £18M contract in January 2016 to deliver the updated MCAS. Babcock Marine and Technology is responsible for the integration of the new systems aboard the ships and was awarded a £3.6M for this task. The project includes installing 600m of new pipework in each ship together with over 8km of new cable. The Upper Auxiliary Machinery Room (UAMR) and the Forward Auxiliary Machinery Rooms (FAMR) have to be almost entirely stripped out and new machinery foundations and uptakes and downtakes fitted.

The MTU 4000 gensets have specialist mounting and are surrounded by an acoustic enclosure, ensuring low radiated noise levels, critical to anti-submarine warfare. (Photo: Rolls Royce)

The new propulsion package fitted to the Type 23s will not only improve ship availability, fuel efficiency and available power but will provide useful experience for the RN as similar MTU gensets are being fitted the future Type 26 frigates. Although the Type 26 is an evolution of the Type 23’s propulsion system there are significant differences. Type 23 utilised a CODLAG arrangement – Combined Diesel Electrical AND Gas Turbine. Both the gensets driving the motors and both Spey Gas Turbines are required to be online to achieve full speed. The Type 26 is CODELOG Combined Diesel-Electric OR Gas Turbine. The single MT-30 gas turbine alone is sufficient to drive the ship at full speed without the need for the motors, and in that mode the gensets can provide power purely for the ships electrical needs.

Although the Type 23’s legacy Spey gas turbines do not, the new MTU propulsion system meets the requirements of the International Maritime Organization (IMO) III emissions directive. Meeting civilian emissions standards is challenging for the unique requirements of naval vessels but it is obviously desirable to maximise fuel efficiency and reduce emissions. The RN has utilised various new hydrodynamic features to minimise drag on its ship hulls. These have been incorporated at the design stage of the modern vessels Type 45, the aircraft carriers and the Type 26 but the older Type 23s have undergone some modifications in service including self-polishing anti-fouling coatings on the hull and propeller blades, stern wedges, and improved propeller designs. The intention is that the Type 26 frigates will be fully compliant with IMO’s MARPOL Nitrogen oxides (NOx) regulations and will be fitted with a Selective Catalytic Reduction (SCR) system together with the efficient MTU4000 20V diesel generators and MT-30 Gas Turbines.

HMS Montrose in the final stages of her LIFEX (May 2017) in Devonport. Babcock’s Frigate Refit Complex comprises 3 covered dry docks and is being heavily utilised for the LIFEX programme. The future Type 26 frigates will not fit inside this facility, although the smaller of the Type 31 designs could probably be accommodated.