There has been plenty of coverage of the Fleet Solid Support ship procurement process but here we take the first detailed look at the winning ship design.
At this early stage, full details are not yet public and there maybe further refinements before construction begins but the outline features of the vessel are available. FSS will be a major leap forward in capability for the RFA and the overall design appears purposeful and attractive. BMT have been working on the project since at least 2019 when the initial mock-ups were made public. The first iteration of the specification called for 6 HRAS rigs which would allow FSS to simultaneously pass 5-tonne loads on two rigs to the aircraft carrier. In order to meet the budget, the MoD revised the specification and the 6-rig, 50,000+ tonne ‘beast’ was subsequently scaled down and the ship will now have 3 rigs able to pass 2.5-tonne loads to the carrier from one rig at a time.
Despite the reduction in size and ambition, FSS will still be the largest stores ships ever operated by the Royal Fleet Auxiliary, displacing 39,000 tonnes, about the same as the Tide Class tankers. Their greater beam and length is primarily because of the additional internal volume needed for storing and handling dry cargo compared with the simpler tanks and pipework of the oil tankers. FSS will displace about 20% more than RFA Fort Victoria (the only solid stores replenishment ship currently in service) having a beam more than 4 meters greater.
The MoD says that compared to its predecessors RFA Fort Rosalie, Fort Austin and Fort Victoria, FSS will “have significantly improved cargo capacity and replenishment capability to deliver the tempo required, have lower emissions and fuel consumption and are adaptable for future roles”. Fort Victoria has around 3,330m3 solid stores capacity but also carries fuel for issue. FSS will be a dry cargo-only vessel and has space for 9,000m3 of ammunition, spares, food and general stores.
As another of the cost reduction measures, FSS will not feature the manpower-saving automation of the Highly Mechanised Weapon Handling Systems (HMWHS) used on board the QEC carriers. Stores movement will be undertaken by the conventional use of Material Handling Equipment (MHE) and lifts in the same way as RFA Fort Victoria does currently. However, FSS has a significantly larger clearway, where stores are brought up from below which will facilitate an improved replenishment tempo. There is also direct access through the superstructure to the flight deck aft for more efficient vertical replenishment (VERTREP) using helicopters.FSS-RFA-Fort-Victoria-Tide-Class-Comparison-1
Like the Tide-class tankers, FSS has a twin skeg hull form, twin shaftlines, twin rudders and the propulsion system is a similar hybrid-electric configuration. It is in the propulsion system that there is most commonality between the two BMT-designed ship types, which should reduce logistic and training overheads. The Tides have a flexible CODELOD (Combined Diesel Electric or Diesel) arrangement. A motor on each shaft propels the ship at low-medium speeds. Two diesel generators supply the power to the motors and the ship. For higher speeds, there are two larger diesel engines which drive the shafts through reduction gearboxes. A significant innovation is that when propelled by the diesel engine, the motor on the shaft can be switched to become a generator and used to supply the ship’s hotel load. Two other diesel generators routinely supply the ship’s electrical power. This arrangement eases maintenance, is fuel efficient and likely will be copied by FSS.
FSS has rather small funnels but their positioning suggests the engine rooms are in a staggered arrangement with the port engine room sited further forward than the starboard. This layout is commonly used in warships and provides a measure of separation so at least one may remain operational in the event of the ship being damaged. Noise in the accommodation spaces adjacent to the funnel uptakes was a problem in the Tide class which has hopefully been addressed in the new design.
Top speed is advertised as 19 knots, a sustained 18 being the viable minimum for naval auxiliaries. Officially the Tide class tankers can manage 20 knots but struggled to achieve this in service. There is a considerable performance difference between a new and empty ship and a fully loaded vessel that has accumulated several years of marine growth on the hull. As larger vessels, it must be assumed FSS will have more powerful diesels than the Tides.
The MoD would not comment on whether FSS has emergency propulsion. The Tide class have bow thrusters for manoeuvring in harbour but the thruster can also be lowered out of the bottom of the hull and rotated to provide emergency propulsion and steering in the event of damage to the main propellers or rudders. A diesel generator in the bow can be used to run this truster in the event of main engine failure. FSS appears to have a similar layout at the bows and includes the same forward mast as the Tides that contains the exhaust for the emergency diesel.
As part of the obligatory governmental net zero commitment, the design is advertised as potentially adaptable in future with “carbon intensity reduction packages”. These include using diesel blended with methanol or biofuels and the addition of hull air lubrication which can slightly reduce fuel consumption.
Self-defence fit appears to be pretty standard with mounts for two 30mm Automated Small Calibre Guns and two Phalanx CWIS. By the 2030s Phalanx will be somewhat long in the tooth and could be replaced by directed energy weapons, assuming FSS has sufficient spare electrical generation capacity. This will be backed with manually-served GMPGs and .50cal machine guns for force protection (The .50cal replaces the Mk44 Mini Gun which officially goes out of RN service in March 2023). They are not shown on the mock-ups but it is likely FSS will also be fitted with soft kill decoy launchers and the Surface Ship Torpedo Defence (SSTD) system and supporting Sonar 2170.
FSS will have core RFA crew of 101 plus up to 57 augmentees all accommodated in comfortable single en-suite cabins. There is more austere sleeping accommodation for another 21 personnel if needed. Unlike most RFAs, the majority of cabins will not have windows or portholes. The MoD confirmed this is because they were not a mandatory requirement and have been omitted as part of the cost-capability trade-offs. The maritime Trade Unions may have something to say about this and with the RFA struggling to attract enough civilian seafarers, it is debatable if this small but unwelcome economy will be worthwhile if it has an impact on morale and retention.
FSS will be fitted with a medical facility with Fleet Time fit – enhanced with extra staff as required. The capacity of the medical suite is unclear but is likely similar to the Tides which have a 3-bed sick bay and dispensary. When the future of RFA Argus was less certain, there had been speculation that one or more of the FSS could be equipped with a much more substantial medical facility to operate in the Primary Casualty Receiving Ship (PRCS) role. Team Resolute says the FSS design has the capacity for the medical suite to be enhanced in the future if required.
How heavy is HRAS?
In anticipation of the demands of the aircraft carriers and the future FSS project, in 2013 Rolls-Royce and built a new Heavy Replenishment at Sea (HRAS) land-based demonstrator and training system at HMS Raleigh. If this rig had been fitted to FSS, it was designed to be capable of transferring 25 five-tonne loads per hour for up to five hours in conditions up to sea state 5. The 5-tonne weight and size requirement was based on the engine module of the F-35 as well as the tactical benefit of speeding up RAS serials which make the carrier more vulnerable than usual. To cope with these loads, the whole system has to be substantially bigger and reinforced, the main jackstay line is tensioned to 18 tonnes, whereas the 2-tonne rig requires a tension of 8 tonnes. The need to handle larger and heavier loads is also a cost and complexity driver in the design for the internal movement of stores.
Confusingly under NATO standards, HRAS is considered to be any payload greater than 2 tonnes. Since FSS will now have 3 rigs rated at 2.5 tonnes it is technically classed as HRAS-capable but this should not be confused with the 5-tonne system originally envisaged for the ships. There is some merit in the argument that 5-tonne HRAS was a ‘gold-plated’ solution and the carriers can make do without it and ensuring the overdue FSS project is affordable and deliverable must be the priority. F-35 engines can be stored onboard the carrier which has some excess storage capacity anyway, especially as embarking the intended 36-jet full-size air group seems to be a very long-term aspiration.
Besides the core replenishment work, FSS will be able to carry out other supporting roles. There will be ‘operational spaces’ for use by embarked forces, presumably briefing rooms and possibly some form of command and control facility. Like all RFAs, FSS will have a military communications fit, and some electronic surveillance capability.
Very early concepts for FSS included a vehicle deck, stern ramp and ‘steel beach’ for offloading cargo into landing craft which were carried in davits. Ambitious aspirations for amphibious capability disappeared from the requirement long before the first FSS competition began but Team Resolute have at least included the option to fit davits for up to two small landing craft. LCVPs are optimised for carrying personnel not freight but would be useful for ferrying medical staff or light stores ashore during HADR operations (as was the case during the 2015 operation launched from RFA Argus to combat the Ebola outbreak in Sierra Leone). Use of FSS in littoral Strike operations would be rather limited, given their high value and limited self-defence capability. Perhaps for follow-on logistic support to a secured beach (with air superiority) using the cranes to offload stores onto Mexflotes and helicopters to fly loads ashore.
The large flight deck and twin hangar would allow FSS to fill in for RFA Argus in the aviation training role at times. As Argus will be re-designated as a Littoral Strike platform, the availability of her big deck for rotary wing aircrew training could be more limited. FSS will also be capable of embarking large items of freight for general transportation as a supplement to the civilian strategic sealift vessels if needed.
The name game
Names for the ships are unlikely to be announced until the first steel is cut but there is speculation they could follow those of previous RFA solid stores ships. The obvious candidates would be RFA Stromness, Lyness and Tarbatness. The Ness class served from the mid-1960s before all three were sold for further service to the US Military Sealift Command in the early 1980s. Stromness saw action in the Falklands War as she had not yet been transferred to the US. These are evocative names that work well together, although there could be some political sensitivity around all being Scottish place names.
Another possibility would be to name them after RFA Resource (1966), Regent (built by Harland & Wolff 1966) and Reliant. All served in the Falklands conflict, although MV Astronmer was a merchant ship converted after the war with the ARAPAHO containerised aircraft handling system and renamed Reliant. A previous RFA Reliant (1957-76) was specifically converted to supply stores and victuals to RN aircraft carriers.
These ships will be a fine addition to the fleet and enable to carrier strike group to operate to its full potential for a sustained period over great distances if required. More broadly, these vessels will considerably enhance NATO’s slim European naval logistics capacity.