The Defence Command Paper published in the wake of the March 2021 Integrated Review promised: “more than £50m will be spent converting a Bay class support ship to deliver a more agile and lethal littoral strike capability”. Here we take a speculative look at the options for the conversion.
The Bay Class Landing Ship Dock – Auxiliary (LSD(A)) vessels were originally conceived to provide follow-on support to amphibious assaults, with additional troops and stores carried ashore by landing craft and mexeflote. While they are still entirely capable in this role, they have proved to be flexible and adaptable as a platform for other tasks, notably mine warfare support and humanitarian aid operations. As uncrewed systems become increasingly important they are also an ideal mothership for UAVs, UUVs and USVs.
The full history and design of these vessels is covered in depth by an earlier article but it is safe to say the three remaining Bay class are in high demand. The decision to convert at least one as an LSS is intended as a stop-gap until replaced by the promised ‘Multi-Role Vessels’ in the early 2030s. The conversion should be complete by 2023 when the first LSS is expected to deploy to the Indo-Pacific region.
A more expensive route would have been to procure a dedicated LSS using an adapted merchant vessel. Prevail Partners had developed the LSS concept and put agreements with relevant commercial shipping companies in place that could have delivered the capability without converting one or more of the precious LSD(A)s. Besides cost, limited personnel numbers, boats and helicopters available to equip additional vessels must also have factored in the decision not to go with the Prevail offering.
The LSS concept is described officially as “a forward-deployed vessel, to respond rapidly to crises, special operations-capable, ready to strike from the sea, to pre-empt and deter sub-threshold activity, and counter state threats.” The most significant difference in role between that of the LSD(A) and LSS is the requirement to loiter at sea for longer periods and be able to generate and support special forces and light raiding operations. This is in line with the Future Commando Force (FCF) concept that envisages smaller, more agile forces not intended to conduct ‘traditional’ heavier amphibious warfare. The development of a new Royal Marines operating model is a necessary adjustment to a changing and more complex battlespace, but it is also a convenient way to avoid the significant costs of recapitalising ships and equipment needed to retain the full spectrum of credible amphibious capability.Bay-Class-LSDA-General-Arrangement
The conversion work is likely to be subject to competition, with A&P Falmouth a leading contender. As holders of the Future In-Service Support (FISS) Lot-2 contract to maintain the 3 ships, they are already very familiar with the vessels and should be capable of this modest project. Cammell Laird would be the other likely contender. Having performed maintenance or refit work on most ships of the RFA fleet they have no history of work on the Bay Class but have more steelwork fabrication experience than A&P.
At the time of writing it has not been confirmed which vessel is in line for the conversion. RFA Mounts Bay completed major refit in late 2020 while the refit of RFA Cardigan Bay is just beginning. RFA Lyme Bay arrived in Bahrain in May 2021 but naval sources suggest she will not stay in the Gulf for more than a year and will probably return home to be converted into the LSS. It is unclear if there is an intention to convert another vessel to support the two planned Littoral Strike Groups.
There may be scenarios where raids are delivered covertly over the beach, but insertion by helicopter is more likely to be needed for special forces operations. In terms of converting the Bay class to LSS, the most obvious need is to improve the hangar and aviation facilities. Currently, the Bays have a temporary fabric aircraft shelter that can provide some protection from the elements typically for one or two embarked Wildcat helicopters. A larger permanent hangar, ideally with space for at least two Merlin Mk4s (or four Wildcats) is needed. This would allow them to be safely embarked for long periods and conduct maintenance, including engine changes and provide a more workable environment for engineers when operating in the heat of the Gulf or freezing High North.
The LSD(A)s were not built with command facilities (like the LPDs). Additional office, planning and command spaces for the EMF and upgrades to communications would be desirable. Upgrades to weaponry are unlikely within a £50M budget. LSS is supposed to either keep a low profile by merging with merchant traffic or be accompanied by escort(s) in higher threat environments. Further investment in offboard unmanned systems should be seen as the main way of increasing their offensive capability.
The original LSS concept also hinted at a more substantial medical capability than currently possessed by the Bay class, possibly a Role 2 facility that would support a full surgical team. (They currently have a 14-bed sick bay, a small operating theatre and a treatment room.) Any improvement to afloat medical capability would be especially welcome to help offset the pending disposal (without replacement) of RFA Argus.
While the RFA crew are accommodated in some comfort, the Embarked Military Force accommodation for up to 350 personnel is adequate but was not really intended to be inhabited for long periods. It may be desirable to upgrade the EMF recreation areas (under the vehicle deck) to be more comfortable, even at the cost of slightly reducing capacity.
The LSS conversion designers must deliver the project within the £50M budget but are also constrained by the limits of the existing platform. Any additional steelwork must not exceed topweight limits and may require work re-ballasting to ensure the ship’s stability. The Bay class are loosely based on the Dutch Damen Schelde ‘Enforcer’ design used for HNMLS Rotterdam, built in 1997. The highest (bridge) deck is one deck lower than the Bays but the superstructure extends further aft, enclosing a permanent hangar for 3 NH-90 helicopters which would suggest there is some topweight margin available for additions to the superstructure.
Additional compartments must also meet modern certification standards and consideration be given to electrical supplies, heating, ventilation and air conditioning services (HVAC).
Modifications to the upper deck must also take into account the position of the funnels, set inboard and amidships, two pedestal cranes and the elevator vital for moving equipment between the main deck and vehicle deck. The elevator is set on the centreline and its position would complicate the addition of new superstructure above. Re-siting the cranes, funnel or elevator might all be possible but each would imply additional time and cost.
The steelwork itself may be relatively cheap but to this must be added the cost of design, new equipment, the re-siting of existing equipment and integration of HVAC, and power supplies with existing systems.
Below are some very simple concepts showing possible options for the conversion. Without details of the specific requirements for LSS, these are only speculative ideas. For the sake of simplicity and cost, the elevator has not been repositioned or any modifications made below the upper deck.Littoral-Strike-Bay-Plus
This is the most basic solution, essentially replacing the fabric aircraft shelter with a simple rectangular steel hangar that almost extends the full width of the ship, apart from the port side where the crane remains in position. This would not require the re-siting of any equipment and it is perhaps surprising that this simple upgrade was not made years ago. However, the LSS may demand more complex modifications and additional command spaces.Littoral-Strike-Enforcer
This has most in common with the original Dutch Enforcer design and is the most likely direction of travel. The hangar extends the full width of the ship, able to accommodate up to 3 Merlin-size aircraft. The pedestal cranes have been moved aft. There is a smaller upper deck storage area but the flight deck could be extended for two spots to support faster launch and recovery of helicopters. Above the hangar is a small Flying control office (Flyco) and two decks for use as offices and command space. The medical facility has been extended to be more than double the existing size, replacing the offices currently occupying the forward part of 1 deck.Littoral-Strike-Max
This is a more ambitious arrangement but would provide more extensive offices, accommodation and enclosed storage space in a separate after superstructure. The midships deck storage area is retained, although smaller and the elevator emerges into a covered area connected by a tunnel to the aircraft hangar to allow vehicles and stores to be moved to the flight deck. The full-width hangar can also house 3 merlins but the flight deck is reduced to a single spot. Engine exhausts would be extended upward into a more traditional twin funnel design that would keep fumes well away from the deck. Flyco is also in the optimum position overlooking the flight deck. The size of this superstructure will place additional loading on the hull that may demand structural strengthening and significant re-ballasting.
It will be fascinating to see how the conversion project progresses and whether the LSS is a success in service. From an operational perspective, the flexibility of the Bay Class suggests they are a sound platform that can easily be adapted to perform in a slightly different role. In a future article, we will consider the bigger challenge of the Littoral Strike Group concept as a whole.