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Can civilian ships be utilised in a maritime security and support role, not a frigate in the traditional sense, but still something useful and low cost, or where speed is a factor?

This is not a unique question, many have proposed similar for many years. The first I read was from Mark Tempest in 2009 at the US Naval Institute called ‘The Department of Cheaper Pirate Fighting’. Mark also blogs regularly about maritime security at his own blog, Eagle Speak. One of the first multi-part series on Think Defence was called a Ship that is not a Frigate, so-called because it was a few thoughts on how the Royal Navy could create a class of vessels that could operate in the area between the RFA logistics support vessel and the frigate or destroyer, specifically on a range of non-war-like tasks. Taking inspiration from Mark Tempest I expanded the concept from re-purposing surplus offshore supply vessels and creating a larger, more flexible ship, utilising an offshore construction vessel as a base. Since then, and before, I have written about the general concept a few times so this is a continuation and consolidation of those various blog posts and older series.

The reason I called it ‘not a frigate’ is that it was not intended to be a frigate on the cheap, or a surrogate frigate, and to emphasise the point so that people would not get carried away by adding medium calibre guns and cruise missiles. The reason this article is notionally called ‘still not a frigate’ is that that still stands. If one wants a Frigate (light or global) ask those nice chaps at BAE or BMT to design and build one for you.

Why bother with doing this?

There are three reasons why one might convert an existing civilian vessel (or use one as a base design)

Time pressure; we converted merchant vessels for use in the Falklands Conflict, and not just the Atlantic Conveyor. There may be an emergent crisis that cannot be resourced within the existing force structure and an imperfect today is superior to a perfect tomorrow. Conversions free up more capable vessels for more important roles in this scenario.

Cost pressure; Smaller nations might wish to generate a capability at a very low cost, or nations with larger budgets may wish to allocate a smaller budget to a specific range of capability areas and might be willing to compromise.

Suitability for the role; Some roles be well suited, a heavy lift or antarctic patrol vessel requirement might be ‘close enough to that provided by a civilian design, especially if time and cost pressures are also included. Suitability for the role might also include being inconspicuous or an ability to blend in with more common maritime traffic.

It is also possible for all or some of these to be relevant at the same time.

Examples of Civilian Conversions or Derived Vessels

The Atlantic Conveyor had a less well-known sister ship that also took part in operations in the South Atlantic. The Atlantic Causeway was pressed into service in the same time frame but with a different set of modifications. Requisitioned on the 4th of May and taken to Devonport on the 6th she was converted to carry, operate and support helicopters. The conversion differed from the Atlantic Conveyor in having a large hangar forward and improved aviation fuel handling facilities. During the operation, she received 4000 helicopter landings and refuelled aircraft 500 times, an impressive feat for conversion and restoration that cost £2million, or about £8m today.

RFA Reliant started as the MV Astronomer, a container ship built in Poland in 1976. After the sinking of the Atlantic Conveyor, the MoD requisitioned her for service. After unloading all cargo and containers, she was sailed to Devonport and converted to the helicopter forward support ship, sailing south on the 8th of June 1982. The six-day conversion included the installation of a landing pad, hangar, RAS gear, communications equipment, additional accommodation and self-defence equipment. In addition to three Chinook, Wessex and Sea King helicopters, the ship had its crew of 34 joined by 53 Royal Navy, 21 RAF and 8 Army personnel. During her time in the Falkland Islands, the MV Astronomer carried out all manner of aviation support, patrol and logistics activities. The one-thousandth landing was completed by a Royal Navy Sea King from HMS Invincible at the end of August.

MV Astronomer

No, that wasn’t a typo, six days.

The Falkland Islands deployment was a great success. In December 1982, Astronomer was leased by the Ministry of Defence and underwent further conversion during which she was fitted with the US ARAPAHO system, a flight deck and hangar facilities for trials. She was later commissioned into the Royal Fleet Auxiliary as RFA RELIANT in late 1983. Cammell Laird and BAE completed the conversion which included two accommodation blocks (called the Village and the Hilton), power and ventilation, water purification and storage, communications, hangar and flight deck, generators and electrical distribution systems, and weapons and fuel storage. It was a much more comprehensive version of what was originally installed, cost £25m. The ship was tested with helicopters and Sea Harriers. In 1984, RFA Reliant played a key role in the evacuation of British citizens from Lebanon, supporting the UK contingent (BRITFORLEB) of the UN Multinational Force (MNF) in Lebanon between 1982 and 1985, Operation HYPERION.

Despite this promise, the experiment was not a success. The ARAPAHO installation, on loan from the US Navy, was not of high quality and would not have fared well in South Atlantic conditions, even in the Mediterranean, there were problems. Design faults meant the system was not watertight and the landing pad surface was so coarse, it resulted in a great deal of aircraft tire damage. A short tour to the Falkland Islands was followed by decommissioning of the ARAPAHO equipment and sales of the vessel back to the MoD. She ran aground in 1995 and was scrapped at Alang, India, in 1998.

Contender Bezant was utilised as an aircraft transport, ferrying helicopters and Harriers south to the Falkland Islands.

Following purchase by the MoD in 1985 for £13million she was converted to an aviation training ship at the shipyard of Harland & Wolff, Belfast, with the addition of extended accommodation, a flight deck, aircraft lifts and naval radar and communications suites. A Primary Casualty Receiving Facility was added before Argus was sent to participate in the 1991 Gulf War.  Another role of RFA Argus is that of RORO vehicle transport with vehicles carried in the hangar and on the flight deck, a role she performed in support of United Nations operations in the former Yugoslavia.  During the 2003 invasion of Iraq, Argus was again present in the Persian Gulf as an offshore hospital for coalition troops, earning the nickname “BUPA Baghdad”. Most famously, RFA Argus participated in OP GRITROCK, the UK’s response to the Ebola outbreak in Sierra Leone, and of course, a star turn in the Brad Pitt film, World War Z.

RFA Diligence is another veteran of 1982, taken up from trade as the MV Stena Inspector. After providing extensive support to the task force she was retained by the MoD in 1983 and additional forward repair facilities were added. She received an extensive refit in 2007 and is now awaiting disposal.

RFA Diligence and Argus have given the UK sterling service.

The Malaysian Navy converted the Malaysian International Shipping Corporation (MISC) Bunga Mas Lima into an auxiliary patrol ship, equipped with a helicopter pad and hangar, small boat handling systems and personnel accommodation for seventy.

The Bunga Mas Lima (BM5) has achieved some success in the counter-piracy role. Another vessel, the Bunga Mas Enam (BM6), was also been converted, rescuing the MT Bunga Laurel from Somali pirates in 2013. Both vessels are owned and crewed by MISC but the security personnel and aircrew are from the Malaysian Armed Forces (MAF). The Malaysian MoD has published an excellent overview of OP FAJAR, their efforts to combat pirate activity in the Gulf of Aden and the Indian Ocean, click here to read.

Both are still in service.

The SeaOwl Group have an offshore platform supply vessel converted for maritime security and aviation training. It has a frigate sized helicopter landing platform, a containerised aviation planning facility and a close combat module for board and search training. They also use the VN Partisan for target drone deployment and recovery, the French Navy’s (ALFAN – Amiral Commandant de la Force d’Action Naval) make extensive use of the SeaOwl VN Partisan.

After what seemed like an age, the replacement for HMS Endurance (Antarctic Patrol Ship) was announced in 2001. The name HMS Protector has previously been used for many ships, but the last was also an Antarctic Patrol Vessel. The replacement was polar research and subsea support vessel called MV Polarbjørn (Polar Bear).

MV Polarbjørn

The Polar Bear was a mere 10 years old at the time, smaller than the Endurance and without a helicopter hangar. She was owned by CG Rieber Shipping, previously operating on the spot market. HMS Protector is also equipped with a survey motorboat, Pacific 22 rigid inflatable boats, landing craft, three all-terrain vehicles and three quad bikes, complete with trailers.

The Royal Australian Navy (RAN) also purchased a similar vessel, the Skandi Bergen, for just under £64 million. She was renamed the Ocean Shield and served until handed over to the Australian Border Force. The Royal New Zealand Navy took an unusual hybrid approach with the Multi-Role Vessel (MRV) HMNZS Canterbury. She is not a conversion, but a new build based on an Irish Sea ferry called the Ben-My-Chree. Construction was a relatively modest £60 million but doubts about seaworthiness were soon confirmed and a series of modifications were made to address them, these costing approximately £40 million.

The UK has also used the SD for non-conventional uses, allegedly!

A more recent conversion example is the MV Cragside, a $73 million conversation and time charter.

The vessel shall serve host to fifty (50) Sponsor personnel with the ability to surge to an additional one hundred and fifty-seven (157) support personnel, for a total of two hundred and seven (207) Sponsor personnel, within twenty-four (24) hour notice.

Modifications included;

Flight Deck. The Contractor shall provide helicopter facilities with the ability to simultaneously launch/recover two (2) MH-60 class or one (1) CH-53E class helicopter with clear, unobstructed vertical airspace. Helicopter facilities shall comply with the requirements of US Coast Guard Navigation and Vessel Inspection Circular No. 9-81 for day and night landings with instrument meteorological conditions (IMC) for the following aircraft: MH6, AH6, MH47G, MH60K, MH60L, MH60M, UH60L, CH47 D-F, OH58D, AH64 A-D, MV/CV 22, HH60H, HH60J-T, SH60 B-F, MH60R, MH60S, and the MH53E.

Hangar. The Contractor shall provide a hangar facility, capable of being NAVAIR certified, with easy access to the flight deck. Hangar shall be capable of housing two (2) MH-60 class helicopters with main rotor folded, refueling probe installed, and tail rotor unfolded in flyable condition (30’W x 75’L x 26’H), as well as 4 (15′ x 5′) air vehicles, GFE yellow gear, spare parts and space to conduct routine required maintenance. The hangar shall be of sufficient size to accommodate two (2) MH-60 class helicopters.

The Cragside was a Flensburger RORO design, not dissimilar to the Point class strategic RORO vessels in service with the UK. She is now the MV Ocean Trader.

This general concept has also been given a great deal of impetus recently with the UK’s Littoral Strike Ship concept.

Things have moved on a bit since 2019 with an announcement about one of the Bay class vessels being converted as an interim approach to support the newly established Littoral Response Group with a renewed focus on smaller Multi-Role Support Ships rather than the larger Littoral Strike Ship.

Multi Role Support Ships (MRSS), to provide the platforms to deliver Littoral Strike, including Maritime Special Operations, in the early 2030s.

Some have speculated that the MRSS will look something similar to the BMT Ellida design, a dedicated design, not a conversion and there remains much discussion about the final form of these ships and overall concept.

Prevail Partners have also continued to develop their proposal for the Mult-Role Vessel.

Canada also continues to work in this area for their Joint Support Ship requirement, although the latter is looking more like a conventional tanker. In the USA, in support of expeditionary operations, the Department of Defense built a number of Mobile Landing Platform (MLP) and Afloat Forward Staging Base, or Expeditionary Mobile Base (ESB) as it is now known, using an Alaska Class oil tanker as the base design.

Lewis Puller ESB (2)

The ESB is an impressive vessel, a very good write up of the type here

Several years ago BMT looked at the options for replacing RFA Diligence under the Operational Maintenance and Repair (OMAR) study. It concluded that the optimum solution was an unpowered barge carried to the area of operations on a Float On Float Off (FLOFLO) heavy lift vessel. The barge was 120m x 30m and displaced approximately 3,500 tonnes.

OMAR Barge

The study suggested using a FLOFLO vessel of opportunity or one on a long term charter.

Iran has recently introduced two similar vessels, the IRINS Makran (441) and IRINS Shahid Roudaki , the former a converted oil tanker and the latter, a converted RORO vessel.

And right at the other end of the scale, a few from Libya, the tugs Assameeda and Almergheb, both equipped with a range of rocket launchers and automatic weapons.

All these examples show the rich history of small and large nations and conventional and non-conventional forces taking advantage of civilian vessels for use in conflict or security. Some have been in response to immediate time pressures by converting ships already available and some have taken a more considered view and adapted civilian designs. Some have been large, some small, some multi-purpose, some very focussed.

It is also fair to say that some have been a greater success than others but none can be dismissed, there should be a place for them in our thinking.

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Roles and Requirements

From above, time, cost and suitability role are the three main factors to be considered. A while ago I came up with the whimsical idea of defining craft by where they sit on the fightiness scale (as stolen from BMT!) and it might be worth a recap.




Anything we generate by converting a civilian design is not going to be in the upper right, they would straddle safety and security, certainly whilst operating alone. When operating inside the protective envelope of other combat ships such as T45/T26 (or coalition forces), or perhaps, with some additional equipment fitted, carry out these roles in a higher threat environment. To labour the point, it is not a fighting vessel, but it might be involved in a wider fight, with some help from its bigger brothers.

Potential roles might include;

  • Training and Defence Engagement
  • Salvage, Repair and Firefighting
  • Medical support
  • Experimentation and Systems Development
  • Survey
  • Mine Countermeasures
  • Ship to Shore Logistics Support
  • Maritime and Littoral Security
  • Special Forces Support
  • Disaster Relief
  • Submarine Rescue
  • Aviation Support

We need to be absolutely aware of the simple fact that such a design would not meet naval specifications, would lack a range of survivability features and in short, would not be a frigate, or even an OPV. The current regulatory and risk regime is very different from the eighties and expectations of accommodation, a world apart. Just lashing a handful of ISO containers to the deck and calling them home is not going to be acceptable except in extremis. This means that conversions need much more attention to detail and reference to an increasing regulatory burden, or a higher overhead. Compliance is not a luxury or gold plating, it is the law, but it makes any conversion potentially more expensive than might be imagined.

In the next few sections am going to look at a range of scenarios, and how they might deliver a useful capability.

Scenario 1 – Converting an Offshore Supply Vessel

We are facing an emergent crisis in the Gulf of Guinea and need to reinforce our Nigerian and West African allies whilst simultaneously looking to a deteriorating security environment in Northern Europe. High-end naval vessels are required for NATO tasks but there is a need for maritime security vessels, time is of the essence in order to avert a humanitarian crisis. We need hulls in the water to monitor and deter piracy and illegal fishing, provide mobile operating bases for small teams of Royal Marines, and the ability to launch and recover small UAV’s.

Let’s go shopping…

In a depressed market, pretty much any type of vessel is available on the second-hand market, but it is obvious that owners will want to offload their least productive or cheap to run ships first. Vessels with the latest in economic power and propulsion systems will be held on to the last for example, likewise, those that are flexible and can be used in different markets. There is a danger in shopping in the second-hand market that one ends up spending more on running and maintenance costs, regardless of the cost of compliance with the latest regulations and standards. We should be under no illusion, buying second hand and converting is not without its pitfalls, and potentially, not cheap either.

But, ships are available right now, and in this scenario, that trumps other considerations. For the purposes of this scenario, we need a seagoing transit van chassis, something that is robust and adaptable, no-frills, cheap.

The classic analogue is the Offshore Platform Supply Vessel, 75m to 90m in length.

These are tough and reliable as the day is long, and whilst the large tank capacity for drilling mud is unlikely to be much use, the large open deck is. The image above shows a vessel that was on sale a few years ago for £1.5m, no, also not a spelling mistake. Most of those available will have dynamic positioning and a range of navigation and crew facilities, but they will be limited. Going up the price ladder, and looking at various shipbrokers sites, newer models like those below are still available for between 6 and 12 million Pounds.

They typically cruise at 15 knots and have accommodation for 20-30 crew. This modest speed means to cover distances, offboard systems will be needed, or a small flotilla of them. Accepting that time is of the essence and the tank capacities will be of little use, everything has to fit on the cargo deck.

We are being cheap today, let’s go with the first one, a UT705 design.

The specifications are as follows;

Dimensions: Length overall, 80.77m. Beam, 18.01m. Maximum draft: 5.61m. Deadweight 3,910 Tonnes

Capacities: Deck Area 55m x 15m. Fuel capacity, 627 Cubic Metres. Water capacity, 477 Gallons. Oil Based Mud 3,996 bbls @ 100%. Brine 2,516 bbls @ 100%. Dry Bulk 172 m3 in 4 tanks

Accommodation; Berths, 26. Cabins, 14 x 1 man and 1 x 12 Man. Workshops, hospital room, gym, galley, crew mess, day room, laundry and stores.

Class Notation; DNV +1A1, EO/worldwide UK DTp

Propulsion; Engine power: 2 x 2400. Fuel Consumption: 8 Tons Per Day. Cruising Speed: 11 Knots. Maximum Speed: 12 Knots. Bow Thruster 2 x 750 BHP. Stern Thruster 2 x 750 BHP. Rudders Twin Spade

Winches and Cranes; Capstans 2 x 10 T. Deck Crane 1 x 2.5 T SWL @ 5m. Tugger Winch 1 x 5 T

Navigation and Communications; 2 x Marine VHF. 1 x Emergency VHF. 3 x portable VHF radios. Internal calling system. Cell call telephone. Satcom “SAT C” System. Navtex Receiver. 1 x Sat-M phone fax. 1 x Gyrostar Gyrocompass. 1 x Skipper GDS 101 Echo sounder. 1 x Robertson AP9 MK2 Auto-pilot. 2 x Racal/Decca Bridgemaster Radars. 1 x Nor/Ron 360 Magnetic compass. 2 x GPS Receiver

Although it is most basic, it is manoeuvrable and capable of operating in extreme sea conditions.

Oh, and did I mention, less than £2 million!

Assuming that after a survey, the basic ship condition is sound, a number of works packages can be defined. This kind of work is bread and butter for many of the smaller UK yards, we need not worry the Clyde. The cost must always be a major factor, the whole point of this example is to show what can be achieved for ‘not a lot’ and in quick time.

Am no naval architect but making a few assumptions/guesses here.

Work Packages

Most of these would be about bringing the ship up to the relevant standards of compliance.

Package 01 – Hull and Fixtures; refresh the paintwork and anti-fouling coatings, ensure all fixtures (mooring bollards, railing, ladders etc.) are sound, remove and repair any structural damage. A new lifeboat (and supporting safety equipment) and ships boat should complete the job. The newer the vessel it is more likely the smaller this package will be, no point in buying a fixer-upper because time is of the essence and spending an extra £5m to avoid spending 6 months in refit is not a bad trade-off.

Package 02 – Power, Propulsion and Machinery; Same as above, all the pumps, generators, steering machinery and associated equipment would be subject to maintenance. They may not be rated for warm water operation and this would be a factor in deciding on refurbishment or replacement. One thing that might force an upgrade is the requirement for power for electronic systems and payload modules, additional generator capacity and distribution equipment, for example, is likely to be required. If it is not practicable to upgrade existing, additional power might be provided by an on-deck containerised system.

Package 03 – Accommodation; Sleeping quarters, gyms, restrooms, offices, galleys, laundry, workshops and treatment rooms can all be brought up to modern standards, either through a quick refurbishment or using containerised systems. A secure ammunition and weapons store would be a new addition. Because there may be additional crew added as part of the mission module approach, the basic services like the galley, laundry and other non-sleeping accommodation should be designed to cater for a slight increase.

Package 04 – Fluid Cargo Systems; on PSV’s, the lower deck contains large facilities for liquid cargo; drilling mud, fresh water, brine and fuel are typically pumped onto oil rigs and other offshore facilities. Probably the easiest thing to do with the pumps, pipework and storage tanks would be to simply leave them in place, but taken together they represent a significant volume that could be used for other things. If it didn’t adversely affect the stability or was too expensive, I would be inclined to use the space for additional fuel, potable water and stores to extend the vessels unsupported endurance.

Package 05 – Electronic Systems; What we should not do is try and turn a £2m ship into a vessel that contains £100m worth of electronics, that would be silly. There are what might be considered a set of baseline systems that allows the ship to operate in its intended roles, namely sensors, ships network, navigation and communications. Satellite communications, secure HF/VHF/UHF radio, 4G and perhaps an underwater telephone would be useful and quick to install. Navigation, surface search and short-range air control radars would be required. Finally, a basic day/night electro-optical system, searchlight and electronic chart would complete the major electronic systems. There is no need for additional acoustic or fire control systems so something low cost like the Chess Dynamics Sea Eagle is appropriate.

Package 06 – Weapons; the images show GPMG, M2 and Dillon Aerospace M134 Miniguns (Mk44), all should be available for basic self-defence, with pintle mounts at appropriate locations. No other fixed weapons should be fitted.

How much have we spent so far?

Any number would, frankly, be a guess, but making an educated guess based on other refits and contracts regularly described in the trade press, would anyone think such a set of modest upgrades and refurbishments would cost in excess of £10-15 million? Add some project management, design and consultancy costs, on top of the basic purchase cost of the ship and some contingency, and my big fat finger in the air calculator comes out at around £20 million. Let’s not forget, this is just for one vessel, the second-hand market doesn’t usually cater for multiples of the same design, especially at the bottom end, but, it demonstrates what can be done for a small amount.

At this point, we have an innocuous-looking, slightly aged, high endurance maritime pickup truck that can operate for extended periods in all types of weather. It has a basic set of sensors and good connectivity with decent crew accommodation, modern facilities, a large flat cargo deck and a new lick of paint. On the downside, it has no aviation facilities, no facilities for loading and unloading vehicles and no accommodation for embarked personnel either. The fitted crane is only useful for loading and unloading ships stores.

Useful, yes, but still rather basic.

The key to its usefulness is the large, flat, open deck, approximately 55m x 16m, capable of carrying 2,500 tonnes. This could support 36 Twenty-Foot Equivalent containers. Double stack and use 45ft Hi-Cube containers and that works out to roughly 3,000 cubic metres volume or 900 tonnes. Instead of containers, convert the space to lane metres (approximately 3m wide) and it translates to 275 lims, 30 MAN HX60 trucks. Obviously, these would have to be craned on and off but it does provide some idea of cargo capacity.

Without modification, it could also perform some of the other roles, but only parts of them. This leads to the conclusion that some additional equipment is needed that will enable modular solutions to be utilised. In addition to the smaller TEU sized module, semi-permanent custom made modules that are as wide as the deck could be fabricated. Modular solutions need not be swapped every other week, another incorrect assumption people often make, but to make the most of them, additional systems are needed.

The following are additional work packages that enable the cargo deck to be utilised for modules and other cargo.

Package 07 – Additional Accommodation; to provide a flexible accommodation space for embarked personnel, immediately aft of the forward superstructure would be a four containers wide installation, three high, similar to that shown in the image below.

PSV Modules

The modules are placed inside a lifting frame that also acts as gangways, stairs, landings and emergency exits. Four containers are approximately 10m wide which leaves ample space on either side for access routes to and from the forward superstructure and cargo deck. The embarked personnel might be able to make use of the ship’s facilities for eating, laundry and other functions, and so the modular block need only cater for sleeping and ablutions, with some office and storage space.

If this is not possible, additional containerised options are available.

The bottom layer of four containers would be ablutions and showers, with the remaining two used as a locker/ready room and office/briefing room. For the remaining eight containers a decision on sleeping density would dictate the final capacity. Using 8-bed containers could provide space for 64 personnel but this would be a maximum and it would probably be better if a mix of densities were installed. Two 8 bed, five 4 bed, and 1 2 bed containers provide a good mix, for a maximum of thirty-eight sleeping spaces. Using 33-foot containers in a 40-foot lifting frame provides optimal density. The accommodation block module results in the loss of 13m length from the 55m cargo deck, leaving 42m for other payloads and cargo.

These are not just drawings, offshore containerised accommodation modules, with all the latest safety certifications, are commonly used and available from a number of vendors.

Mention the word module and people tend to think of the Royal Danish Navy Stanflex or the US Navy’s LCS and jump straight in with why it is a bad idea. The reason for this is twofold, it may well be a bad idea, but mostly, because the wrong reasons for modular payloads are highlighted. The idea that a sea frame can be an ASW frigate one minute and an MCM vessel the next, purely by virtue of swapping a few modules is clearly suspect. For these highly complex and difficult tasks, the ship system crew must be focussed and integrated. But if the idea of changing roles and modules every other week is put to one side, modularity starts to make a lot more sense. Common physical attributes, electrical, data and other interfaces, compliance with a set of known standards and even common lifting points allow the module to be developed in isolation from whatever is carrying it and fitted to a vessel without each vessel being redesigned to suit. As systems and ships evolve at different speeds the benefits of this become obvious. Add ease of maintenance, damage repair, familiarity and training, and the arguments for modular payloads become compelling. But we need to be pragmatic, we need to be realistic about what can usefully be modularised and we need to be certain where the limits lie.

The offshore industry is a long-standing user of modular systems and approaches. Beyond various stores containers, there are accommodation, power generation, compressors, medical, laboratory, ROV launch and recovery, workshops and even blast resistant refuge modules for use on production platforms. All of these are based on the familiar ISO container format, although other sizes are used as well. Indeed, some topside modules are huge and only moved on decommissioning. For use in the offshore industry, these modules have to comply with a significant amount of safety-related regulations including maintenance of a positive pressure environment and high levels of fire resistance.

Package 08 – Services and Additional Modular Accommodation; along both sides of the cargo deck, services and utility connection panels would allow modules and equipment to be connected using flexible cables and hoses. By using the standard 20ft ISO container as a universal module shape, the multi-services panel spacing can be easily determined. Modules can simply be placed, secured and clipped into the relevant service or utility.

More complex modules are also available.


Control Cabins

Power generation


Data Centre

Diver control

Decompression Chamber

The modules are used on both static facilities and support vessels, and all are designed for the demanding offshore environment. As a general approach works, it is economical and well accepted. But crucially, the industry recognises the limitations of the approach, not everything is modular. It would seem, therefore, that the modular payload concept stands or falls on the level of complexity and integration with the host vessel, but it remains a valid approach.

Although not in the offshore market, Powell Safety Solutions market a containerised solution for prisoner containment at sea, called the ISO Container Cell.

All these can be arranged, stacked, and situated into the optimal mix. The size of the open deck left available would be dependant upon the mix of modules as described above but it would not be unreasonable to assume between twenty and thirty metres of open deck space would be available.

It is interesting that the Royal Navy has recently started to work on a system called NavyPODS

The Ministry of Defence (the Authority) welcomes responses to this Request for Information (RFI) in order to understand the ‘art of the possible’ in regards to the potential future creation of a number of deployable mission modules, known as NavyPODS (Navy Persistent Operational Deployment System).

Each deployable mission module would be expected to take the form of an ISO equivalent container containing a system, or multiple systems, that contribute towards a mission specific capability.

It is envisaged that each mission module will have a COTS power, fibre and antenna ports panel allowing maximum flexibility for plug and play capability, potentially with the capacity to host NELSON Data Platform in a pre-installed NELSON Edge Cloud Server.

Package 09 – Crane; a fixed pedestal crane would allow small craft and USV’s to be loaded and unloaded. There are many types of marine and offshore cranes, available from a broad range of manufacturers such as Palfinger, TTS, Leibherr, Pellegrini, Heila, and Kenz, take your pick.

A more sophisticated davit system would be desirable, and much better than just a crane, so…

Package 10 – Davits; launching small craft using the main crane would not be ideal, indeed, in higher sea states it would be dangerous. Therefore, boat launch davits will be required, much of the utility of this ship is derived from its small craft. They would cut into the deck space but it is a worthwhile trade-off. Manufacturers include VetsadvitMacregorCaley and Norsafe. Go for a model that can support craft up to 15m and it could easily accommodate the Thales/ASV Halcyon for MCM, the ArcIMS for combined influence sweeping, combat support boat, Army workboat, Pacific 24 and Offshore Raiding Craft.

Go up to 20m and increase the weight and even the LCVP or a Combat Boat 90 are possible.

If it were operating in the MCM role, there would be ample space for SIX Halcyon davits and enough room for four lengthwise control containers, stores and workshops, these could also be double stacked with ease. Lose two davit slots and this would free up enough room for a 15m long landing pad for UAV’s, with some storage space underneath.

Package 11 – Landing Deck; Assuming at least two (one each side) 15m davit leaves 24m available for other uses, about the same size as a Type 23 Frigate helicopter landing deck. Clearly, fitting a helicopter deck would be on a semi-permanent basis and given the scope of the other work packages, would not provide open deck space for anything else. It would be the accommodation block, a pair of davits, a small amount of clear space between them and the landing deck, and nothing else. It could be fitted in such a manner that there was some space available beneath it but the handling equipment would add additional cost, it remains an option though and would provide approximately 12 TEU’s worth of space, or 120 lane metres for vehicles. More likely in this scenario would be space for something like a Boeing ScanEagle, something the Royal Navy already has experience with, and an essential tool for this role.


In this particular scenario, where time is limited, the resulting group of vessels would be able to provide security assistance to our allies, covering a reasonably large area by exploiting the reach of something like a pair of Scan Eagles and the speed of small craft like Pacific 24’s or Offshore Raiding Craft. Combine those with commercial satellite services for imagery, AIS and signature tracking, and I think a pretty cost-effective package could be created relatively quickly, 3 to 6 months perhaps.

Helicopter facilities would become the determinant factor in configuration. Facilities for a Wildcat (or similar) helicopter would still provide enough space for 4 12m davits. The additional personnel would likely be Army or Royal Marines, with specialist UAV operators as required. In addition to the four small craft (Pacific 24’s, Offshore Raiding Craft etc.), there would be ample space for a small UAV like Scan Eagle and 4 or 5 container-sized modules for operations rooms and stores, perhaps even prisoner containment. An alternative might see the deck space used for four Combat Boat ’90s or similar, although there would be only five or six metres of open deck space left over for UAV launch and recovery.

Operating helicopters would represent a significant step up in complexity, so unlikely

For other roles;

Humanitarian Assistance Disaster Response; the basic configuration, without a landing pad, provides a good platform for HADR. Accommodation for a combat engineer and logistics troop, plus a handful of other specialists. The two davits could be used for a Pacific 24, Combat Support Boat or even a new build Alnmaritec Wave Supplier landing craft (similar to that carried by HMS Protector). The deck space, used for a disassembled Mexeflote, vehicles and stores containers. When on location, and assuming no port facilities exist, the crane would offload a Mexeflote, stores or vehicles onto it for transport to shore. In this configuration, the open deck space left would be 15m wide by 25m long. A couple of MAN HX 4×4 trucks, two JCB Telehandlers, two JCB 4CX and a couple of Land Rovers would be joined by 16 20ft ISO containers of relief stores and engineering tools and equipment.

Training and Defence Engagement; It seems to me that the VN Partisan provides a near-perfect configuration for training. The only exception would be where the Partisan has the containers mid-point on the cargo deck for aviation training spaces, the MSS accommodation units would take up this space, so only a minimum aviation training space could be provided. If aviation training were dispensed with, or limited to small UAV’s like a Scan Eagle or Camcopter, the smaller flight deck and space beneath, would provide valuable training facilities.

Medical Support; am not convinced there is enough space for medical facilities so, in this configuration, it would unsuitable for the RFA Argus role but still might be useful for medical support in a HADR context, although again, capacity would be limited.

Salvage, Repair and Fire Fighting; an 80m PSV like this has about 30m less length than RFA Diligence which represents a lot of lost space, so in this configuration, like medical, am not convinced would be suitable. Additional cranes and workshops would be required, turning a cheap vessel into an expensive vessel. Therefore, this version would not be a suitable RFA Diligence replacement. Like medical, there might be some possibility of using it as a secondary repair and salvage vessel, accepting the reduction in overall capability.

Experimentation and Systems Development; I think it would be taken for granted, that the large open deck, crane, services connectivity and additional accommodation would provide a very good platform for experimentation and systems development, especially emerging unmanned surface vessels and aerial vehicles.

MCM and Survey; whether this example would be of any value in the MCM role is entirely dependent upon the evolution of unmanned off-board systems, likewise for the survey. Survey tasks will rely less on unmanned systems for specific tasks but making the assumption that the unmanned revolution arrives, this example could easily carry 6 small unmanned craft like Halycon or ArcIMS. Even with this payload, it has the space for a comprehensive command and control fit, a data centre for information processing, basic maintenance facilities, disposal vehicle magazines and communications equipment. Containerised Launch and Recovery Systems (LARS) are also available off the shelf for the current generation of REMUS and Seafox unmanned systems. Other than MCM direct, such a conversion might also provide suitable facilities for the MCM support role.

Ship to Shore Logistics Support; in addition to carrying supplies, vehicles, personnel and engineering plant for port repair, another suitable task would be that of providing a ship to shore fuel transfer capability. With one of the davits for an Army WorkBoat or Combat Support Boat, and sufficient deck space for hose drums and the floating pump and manifold of the Joint Operational Fuel System, it could provide a capability we only have in limited capacity now.

Special Forces and Intelligence Support; whether carrying raiding craft, small landing craft, vehicles, personnel or even a swimmer delivery vehicle, the carrying capacity and flexibility afforded by the open deck space would provide obvious utility for special forces. Containerised signals equipment could also be used to provide an additional and innocuous capability for gathering intelligence. Unmanned systems would also be potential for carriage.

Submarine Rescue; in its bare configuration, it would provide an excellent platform for the NATO Submarine Rescue System.

It may seem counter-intuitive to buy something for a couple of million Pounds and then spend twenty-five million on pimping it up, but if it allows us to save millions on buying new ones, maybe it is not a bad investment. However, if the second-hand approach forces too many compromises and is poor value for money, there is still the option to buy a ready-made design and build new.

The PX 121 is a basic 83m platform supply vessel, but given it has about 30 years of evolution over our second-hand example, the latest designs and equipment come as standard. It is about the same dimensions as the UT705 so module capacity and configuration would remain largely unchanged.

If we don’t mind keeping significant design changes to a minimum and going overseas for the build, prices are actually quite low. Recent contracts include a pair for less than $29 million each, about £20 million.

Although the X Bow does look rather futuristic, the PX 121 is about as simple as they come. There are many other similar designs, from Rolls RoyceSTXVard and Damen, for example.

The open deck of an 80m Platform Supply Vessel provides an opportunity to mix and match modules and open space, each layout optimised for the mission. For some roles, it would be entirely unsuited though, and other approaches would be needed. But for many of the others, this example does provide some glimpse into the possibilities. The main downside I can see with this is their pedestrian speed, top speeds are generally in the 14-15 knot range, far from ideal. Also, the lack of aviation facilities is a big problem for many of the roles. If we are willing to compromise, again, reinforcing the point that a merchant conversion is a collection of compromises, then this route may well provide a ‘bargain basement’ solution in no time at all.

The next example will examine a new build, not a conversion.

Scenario 2 – New Build Modified Offshore Construction Vessel

In this scenario, more time and money are available. In response to a growing need for providing security for submarine cables, building underwater infrastructure in support of uncrewed underwater vessels (UUV) and general maritime security, a large flexible design is required.

The previous example showed a basic offshore platform supply vessel conversion, taking a second-hand UT705 as the starting point, or, buying a new vessel of similar size. What seems evident, is that whilst useful in some roles, the lack of aviation facilities and very low speeds severely limited its utility. By improving aviation facilities, the one thing that made it useful, space, was curtailed. This leads to a conclusion that if we are intent on either converting a merchant vessel or taking one as a start point, it probably needs to be longer than 80m. Vigor Industrial and Ulstein did collaborate to propose an X Bow based vessel for the US Coastguard, based on a specialist offshore design. The SX-151 was 100m long, 16.5m wide and with a top speed of 22 knots. A large hangar, mission bay and accommodation for over 120 personnel completed the design. It was perhaps a bit too radical for the USCG, who knows, but it didn’t progress.

Submarine tenders and other patrol vessels have also been proposed based on the SX 119 Field Support/Standby Vessel.

The Field support/Standby role requires a multi-purpose design for rescue, oil recovery and towing so they tend to have higher speeds, excellent firefighting capability, flexible small craft handling, plenty of accommodation space and improved helicopter handling facilities. 

The French are bringing into service a pair of vessel designs, four of the Kership Bâtiment multi-mission (B2M, “multi-mission ship”) and four of the Bâtiments de Soutien et d’Assistance Hauturiers (Offshore support and assistance vessels BSAH) Even the Russians have a similar idea with the Zelenodolsk Design Bureau Project 03182 and 23310 designs.

These ideas use a derivative of designs in use in the offshore industry, why is it that this shipping sector produces such a rich vein of innovative and low-cost designs, three reasons I think?

Evolutionary Maturity; the basic superstructure forward design has remained relatively unchanged over many decades of demanding operation in extreme environments such as the North Sea. But what has changed over this period are the details. Refined in response to demanding customer requirements, designers have responded over many iterations to the point where mature designs of every kind are available almost off the shelf. The supply chain and support ecosystem are equally mature, and this brings its own cost benefits.

Competition; a vibrant and healthy global market invariably has competition and this competition has created a fertile atmosphere for innovation. Because there are many experienced designers, shipyards and suppliers worldwide we can tap into this extremely competitive market and drive out benefits. This is in sharp contrast to naval shipbuilding which is generally sclerotic, relying on government subsidies and often failing to innovate at the same rate.

Innovation; although the fundamentals have remained fairly constant, subsystems have evolved at a rapid pace, benefitting from the competition, steady demand and an overwhelming need to reduce operating costs by increasing utilisation. Wave piercing designs such as the Ulstein X Bow are genuine innovations that we can take advantage of, the innovation being essentially paid for by the oil and gas industry. Power, propulsion, boat handling, whole ship control systems and positioning technologies have all benefited from an atmosphere of commercially driven innovation.

The more complex offshore support vessels, such as those used for pipe-laying, seismic research, dive support, well intervention, field support and construction tend to be larger than straightforward PSV’s, between 100m and 180m. They are designed and built by organisations such as HavyardWärtsiläUlsteinRolls RoyceSTXVard and Damen The reason I have elected to ‘go large’ for this example is because of the trade-off between payload space and aviation space, a larger vessel has more space, and it is space that really allows the concept to get going. Given that they also contain a high degree of specialist equipment like saturation diving facilities, moon-pools, heavy-lift subsea cranes and pipe laying equipment, a second-hand vessel would include a great deal of equipment removal before any conversion could start. So, it is probably better to start with the basic design but build a new one.

One such innovative vessel is the multi-purpose subsea Ulstein SX-121


Ulstein has designed and/or built six such designs over the last decade, costs have varied as there are obviously slight differences in final specification but the first few between 2006 and 2008 varied between 600 Million NOK and 900 Million NOK, approximately £50 million and £75 million. More recent orders in 2012 and 2013 averaged £65 million. It would seem reasonable to set the baseline design and build cost at £80 million.

Specifications for the SX-121 Viking Poseidon include;

Dimensions; Length: 130m Beam: 25m Draught (max): 7.8m Speed (max): 14.5 knots Deadweight: 10,400 tonnes. Deck area 1,620 m3

Capacities: Fuel oil (MDO): 3280 m3 Freshwater: 990 m3 Technical freshwater: 519 m3 Ballast water: 7700 m3

Accommodation; hotel facilities for 106 persons, 6 state cabins with day and bedroom, 46 one-bed cabins, 13 two-bed cabins, 7 four-bed cabins. All cabins with separate toilets and showers. Hospital and sickbay. Galley, scullery, mess (60 seats), day rooms, smoker’s day rooms, dry provisions, cooler, and two freezer rooms. Misc. conference rooms, 30 seat auditorium, offices and heli reception. Deck pantry, wardrooms, laundry, trim/games room. ROV Control room, online room, offline room, workshops. All facilities are suitable for male and female crew.


Power and Propulsion; Two tunnel thrusters, two swing-up azimuth thrusters.DP3 positioning system. Diesel-electric power and propulsion plant, Four main generator engines, each of MCR 2850 kW. Two main generator engines, each of MCR 1530 kW (1450 kWe / 1611 kVA) at 900 rpm. Exhaust catalyst for all six engines. Fuel consumption, harbour 5m3 per day, 12 knots 38 m3 per day.

Winches and Cranes; Knuckle boom shipboard/harbour crane, 10 tonnes at 20 m outreach. Two Folding cranes, 2850 kg at 10 m outreach. 250-tonne Active Heave Compensated Offshore Knuckle Jib Crane. Main winch SWL 200 tonnes single line, 3000 m net hook travel. Auxiliary Winch SWL 25 tonnes. Two combined windlass/mooring winches, One double mooring winch, pull 12.5 tonnes, Two tugger winches, pull 12 tonnes, Two mooring winches aft, pull 12,5 tonne

Navigation and Communications;  S-band ARPA radar and X-band ARPA radar, Digital chart system ECDIS, Radio installation according to GMDSS – area A3, Satcom C, Fleet-77, Two V-Sat communication antennas Internal Communication ULSTEIN COM® common distribution of automatic telephone, data network and satellite TV antenna signal to all offices and cabins. Telephone system, separate PA, DECT.

Other; Two moon pools with well vented dampening chambers at all sides 8m x 8m and  5m x 5m. Two enclosed lifeboats with davits, each of 106 person Life rafts: Four off 35 p. and two off 37 p., in davits. MOB boat (10 persons) with one-armed davit. Work class ROV hangar and launch/recovery equipment, module tower, 22m 14.7 tonnes capacity helideck, a multi-skidding system for 100-tonne pallets, reinforced deck. Two Freshwater generators, 15 m3/24h, One Reverse osmosis plant, 25 m3/24h

From a systems and capacities perspective, this is a world away from the UT705 in example 1, accommodation is of the absolute highest standard, ships systems, safety, power, positioning, likewise. Using the Viking Poseidon allows a start point to be established but there are a number of design features and systems we either don’t want or want to change. The goal is still to minimise this amount of change, but in our context, am struggling to see the value of a well-intervention tower.

Making Changes to the Base Design

Power and Propulsion; A top speed of 14.5 knots is still 3 or 4 knots short of what would be acceptable. The diesel power generation capacity is used for the high demand deck machinery so basic installed power may be enough. If not, a modest increase of a few knots may not increase costs a great deal. If we could go from 15 knots to 18 knots within the existing hull form, it would be extremely desirable to do so. Given one of the principles of MSS is to embrace the concept of experimentation, there may be room for testing new systems such as a DC Buspermanent magnet thrusterscomposite propellersducted propellers or rim thrusters. Another Ulstein design, the PX105, features a seawater injection system for exhaust gasses. Instead of routing the exhaust pipes up through the ship, leaving behind the bridge as per most designs, it is exited at sea level. This is done to provide an improved field of vision from the bridge but there are obvious tactical advantages as well.

Accommodation; No changes are likely to be needed to the basic hotel facilities. Capacity is enough for the ship’s crew and approximately 60-70 embarked personnel. The accommodation also includes a range of offices, briefing rooms and workshops, these may need some minor changes. Weapons and explosives storage would need to be incorporated and the hospital/clinic facilities improved and expanded. The spacious bridge area might also be modified to include an operations room. The ships boat and lifeboat deck would remain unchanged.

Helideck; The helicopter landing pads seen on offshore construction vessels are used conventionally for crew changeovers whilst the ship is maintained on-station. They are not usually used at night and tend to be limited in sea state operability. On HMS Protector, the helicopter deck was moved from the forward position to the cargo deck.  The typical manufacture of such helicopter decks is the Dutch company, Bayards. Constructed of aluminium, they can also be fitted with various additional fixtures such as lighting and automated fire monitors. They have also joined forces with Barge Master to develop a stabilised flight deck. Although this type of helideck does provide the ability to move personnel they are of no use for cargo or vehicles, so if this design is to exploit helicopters fully, it needs a more conventional solution. If it is to operate helicopters, as opposed to just provide a landing facility, it will also need a hangar and space for maintenance and stores, fuel, weapons and other supplies. The Viking Poseidon helideck should therefore be deleted from the design, another saving of cost and top weight.

Weapons; The same applies for example 1, basic pintle-mounted automatic weapons and man-portable systems only.

Electronics; Much like example 1, the principal changes would be to install a military communication system and basic radar/electro-optical sensor fit.

Fluid Cargo; Like example 1, any drilling mud and bulk powder tanks, pumps and pipes can be removed and used for other purposes, also as example 1, most likely stores and fuel. This removes costs and complexity whilst providing for additional spares, and space for food, construction materials and other stores.

As can be seen from above, the changes at this point are minimal, the most significant changes would be those to the working area, above and below it. There would also be changed in the ROV operating area in the main superstructure.

Moon Pool and ROV Hangar; Vessels working on deep offshore oil and gas facilities generally use tethered uncrewed systems or Remotely Operated Vehicles, sometimes at extreme depths in excess of 2,000m. Most of the MCM/Survey unmanned systems are relatively compact in comparison to the large, heavy-duty, ‘work class’ ROV’s commonly used in the offshore industry and tend to be autonomous or untethered.

Moon pools are designed to provide offshore vessel operators with maximum operating time in deep water and extreme sea states, time being very definitely money. Mines countermeasure norms might be inshore, shallower water and less extreme weather so the advantages of a moon pool might not be as evident and given that they take up considerable volume and add complexity and cost.

The rectangular block immediately to the stern of the bridge is for these work class ROV’s, one is launched through the moon pool and the other through the large vertical doors. The moon pool is 5mx5m and extends from A deck to the bottom of the ship. From A deck to the uppermost deck, D Deck, space is used for ROV handling and storage. Together, this is a significant volume (shown with a blue breakout in the images below).

Moonpool damping tanks reduce wave motion so the ability to covertly deploy a UUV in high sea states does provide value. Removing the moon pool, ROV handling systems and the ROV itself, removes a significant cost element but given increasing future demands for very deep water submarine cable intervention, whilst taking up a great deal of space, this block and capability should be retained.

Deck Fixtures, Cranes and Winches; The deck is extremely robust with a high loading capacity, we might save some money by slightly reducing this but another big saving would be had by removing the skidding system. A skidding system is used to move extremely heavy modules and undersea construction equipment.

The large 250-tonne AHC crane weighs in excess of 350 tonnes without the below deck machinery. We don’t need it, so it can go. In order to resist the turning moment when using the crane at depths of hundreds or thousands of metres, the vessel is fitted with a significant anti heeling system, tanks, pumps and control systems. Although a crane will be part of the ultimate design, it is unlikely to be of such high capacity, so the anti-heeling system could be scaled back as well. The smaller crane will have value in the final design so can be left in place.

The cargo deck would be approximately 110m long by 25m wide (although the actual cargo space might be slightly smaller due to walkways and cargo rails. Looking at images of the MV Sarah or Skandi Constructor, also SX-121 designs, they both have a mezzanine deck at the stern.

The Normand Installer also shows a similar deck arrangement and the various seismic survey vessels have built up superstructures for the full deck length.

This provides a good indication of what can be done, simply extend that mezzanine deck forward to the superstructure and it results in a large flat open deck, underneath the main deck, and underneath that the tween deck, all of roughly the same dimensions except for the tween deck which is shorter due to propulsion machinery. The tween deck would be 7m high and the main deck, slightly lower. The 7m tween deck would be high enough for all in-service vehicles, in-service construction plant on their transport trailers, a high cube container on a trailer and even a Merlin helicopter.

Like Example 1, the main deck will need service connection panels, this is quite important to extending the functionality of the vessel. Air handling, lighting, fire detection and suppression systems would also be fitted. And that is pretty much it in terms of deck configuration, mezzanine deck, 8-10m high enclosed main deck and 7m high tween deck, the latter two with service connectivity and all with appropriate tie-down/lashing points.

Aviation is an important component of most role sets but aviation facilities can be complex and inexpensive. Deck handling equipment, tie-downs, night vision device compatible lighting/markings, landing aids, fuel handling and a number of other systems add to the cost. Modelling deck movement is also a complex task.

But it is important.

The mezzanine deck would therefore effectively form a large single flight deck, 110m long and 25m wide. It should also be capable of supporting a fully loaded Chinook. The mezzanine flight deck can also be used for vehicles, equipment, containers and modular systems.

A hangar is an essential item, it provides sheltered maintenance and storage space for helicopters and UAV’s. There are two basic options for a hangar, put one on the same level as the mezzanine deck or install a lift to the main deck and use that. Retractable hangars can be used when space is at a premium and a temporary Rubb shelter is a quick and cheap way of providing temporary covered space. A hangar on the same level as the mezzanine flight deck would reduce the usable length of the deck but a lift to the main deck would reduce its useable length.

The preferred option is to create a hangar on the same level as the mezzanine flight deck, sized to house two Merlin or Wildcat helicopters. With blades folded, a Wildcat is approximately 14m long, 4m high and 3m wide. A Merlin, approximately 16m long, 5m high and 5m wide. With blades and tail unfolded, a Merlin is 23m long, 7m high and 19m wide. 31m long, 19m wide and 7m wide, a Chinook with rotors turning could fit. 20m long, 9m high and 10m wide and a folded CH-53 would fit. A V-22, when folded, requires 19m in length, 6m width and 6m height. Have a longer hangar, the flight deck becomes shorter but making the hangar 35m long allows the largest helicopter to fit yet still provides 65m unimpeded length for aircraft and UAV flight operations, comfortable for a Chinook, Merlin, CH-53 or V-22. Making the hangar the full width, 25m, also allows rotors turning Chinook to fit. The hangar would therefore be 25m wide, 35m long and 8m high, a large space, but one that allows the largest helicopters in service to fit, and multiple smaller types. Now, making hangar doors that large may be an interesting challenge for manufacturers like Par SystemsCurtiss WrightFHS, and Aljo.

The top of the hangar is neatly in line with E Deck.

Forgive the crude diagram, but this is roughly what it would look like.

The Fort class replenishment vessels provide a good example of large hangars, if a single piece door is not practicable, splitting the door and making the hangar only accessible to helicopters with rotors folded may be the only solution available. Either way, the core objective is to have a large flexible hangar with an appropriate door mechanism. A small air operations control room will also be required.

On smaller vessels, like frigates and destroyers, in order to secure and move helicopters in higher sea states, they need a variety of systems like the Claverham Deck Lock. For large ships or small ships in calmer weather, an electric tractor unit is used to move the helicopter. Given the large size and designed-in stability of the SX-121, it may be possible to dispense with these systems and just make use of tie-down points. An air weapons system will store and move air weapons from their storage locations to weapon preparation areas prior to transfer onto aircraft. Re-stowage of unused munitions is also part of system operation and a high degree of automation will reduce manual handling. Helicopter Landing visual aids and lighting will be required, similar to those provided by AGI Limited There is a big difference between providing a helipad for infrequent crew changes and the facilities required for safely operating helicopters and UAV’s from the ship, but it is an important function and one which requires the appropriate specification.

Doors, Lifts, Access Ramps and Cranes; The ability to gain access to the decks, move vehicles, personnel and modules between them, and launch and recover small craft and unmanned systems is fundamental to the design. The first thing to consider is how vehicles, modules and containers can be loaded onto the main and lower decks. Although it would increase flexibility, specifying a slewing quarter ramp at the stern of the main deck will add a great deal more costly than a simple side door and ramp. In the interests of economy, two side doors near the forward superstructure will allow easy access for vehicles and cargo from the quayside.

These are not constant tension and cannot be lowered to sea level which does preclude using them to load pontoons but that is an acceptable trade-off.

Once loaded onto the main deck, vehicles and stores will need to access the lower cargo deck. Options for the lower cargo deck boil down to a ramp or lift. A lift would require substantial machinery and likely to impinge a great deal on available space. RORO ships commonly use ramps, either fixed or hoistable, to access lower decks. A fixed ramp would need the careful placement to accommodate vehicle and container handler turning circles but it is a very cheap option. A ramp usually takes up eight times the deck height, approximately 56m, at a single lane width of 4m. Taking access space and turning circles into account, this would be pretty much the full length of the lower deck. Electrical or hydraulic ramp covers are another common piece of equipment that provides a watertight seal and allows the ramp area to be used on the upper deck area.

Being very generous with spacing to allow for tie-down bars (instead of floor-mounted twist locks) there would be enough space for 30 TEU, 60 if double stacked. Using 4m as a lane metre width, again, generous, this works out at 240 lane metres, 60 Land Rovers or 20 MAN HS 6×6 trucks for example. The lower deck would be used as a simple storage area, no roof gantry crane and no service access points. A basic ventilation and fire detection/suppression system would complete the installation, perhaps with some under ramp pallet racking and fire doors to partition the area. The reason for this simplicity is two-fold, the first cost, and second, the equipment contained on this deck will not be frequently moved. The main cargo deck will be used mostly for modules, small craft and unmanned systems storage and movement.

There are three main challenges;

One; equipment may need to be moved during operations.

Two; equipment may need to be launched and recovered to the sea.

Three; modules may need services such as power, water, chilled water, compressed air and waste.

A deck grid system with multiple tie-downs and retractable twist locks will allow containers and lifting/storage cradles and frames to be secured against ship movements. Modules will generally be ISO container-sized but small craft such as patrol boats, or unmanned systems, may fall outside these standardised dimensions. Vehicles can be lashed using strops and chains so lashing points must be distributed throughout the two deck areas.

If chains and strops are used to tie down containers from the top, the angle of the chain or strop is such that space is needed between containers to form the correct angle. This is not acceptable in a space-constrained deck area so pop up locking risers can be fitted on the gridded layout that container twist locks can be fixed into. The NDM Cargo Securing System offers another alternative.

Moving boats, boat cradles, unmanned systems and modules can be carried out using fixed or mobile systems.

Container mobilisers, both manual and powered, can be used to rapidly move containers and lifting frames around the deck, they can also be used for loading and unloading to the quayside. Not everything has to be powered and simple mechanical equipment still has utility, Recotech in Sweden make the 17-tonne capacity Wing LiftAnga in Poland and Haacon in Germany also make similar equipment that can be used for limited moves and loading.

These manual systems can be slow and have a lower lift weight capacity but the advantage of not needing power is obvious, especially for the wheeled lifting jacks. They also allow containers to be loaded and unloaded from vehicles without any MHE but would be dangerous to use onboard in all but the calmest conditions.

Powered systems address a number of the problems with using manual systems. The US DoD, as part of the wider Seabasing initiative, have also been investigating the problem of moving ISO container-sized loads at sea. The Dense Pack Access Retrieval and Transit (DPART), omnidirectional aircraft and vehicle platforms and Wheeled Container Lift and Manoeuvring System (C-LMS), for example.

A high-level X-Y gantry crane system could also be fitted to access the full length and width of the main cargo deck. There are a number of manufacturers of suitable marine gantry cranes including StreetStahl and Demag, to name only three. They can include multi-point lifting to prevent loads swinging and rotation devices for accurate placement. The next challenge is launching and recovering small craft and unmanned systems to the sea, this requires access doors and a means of lowering and raising the loads into the sea. We can look at vessels like the Type 26 Frigate, US Navy Sea Fighter, Littoral Combat Ship and offshore support and construction vessels for examples. The main problem is handling large and cumbersome loads in high sea states and traversing the splash zone, safely.

For the Sea Fighter vessel, it was the UK’s BMT Nigel Gee that completed much of the development work. The mission bay system allowed a fully loaded 16 tonnes ISO container-sized module to be moved from the flight deck to the cargo deck and then positioned to the appropriate location, including the stern launch ramp that could be used for 7m and 11m RHIB’s. Sea Fighter module handling was a clever system, but it was space constrained to only 12 mission modules, the load area was restricted by vertical supports and importantly, could not be used underway.

The Type 26 Frigate (or Global Combat Ship) mission bay will accommodate a range of small craft such as Inshore and Offshore Raiding Craft, Sea Boats (up to 12m long) and up to ten 20ft ISO containers. In addition to boats and containers, it can also accommodate a Merlin or even two Wildcat helicopters. Expanding on the significant investment would make a lot of sense, although Palginger and Vestdavit offer alternatives.



For launching unmanned and autonomous underwater vehicles many of their manufacturers also produce specialist Launch and Recovery Systems (LARS) that could be easily incorporated into the cargo deck. Whether the REMUS 600 will be part of the future Royal Navy suite of MCM equipment is not clear but Kongsberg makes a containerised LARS that could be used through a side door.

A stern ramp is often used in vessels that require launch and recovery of rescue craft very quickly and this technology has also found its way into a number of naval and coastguard vessels. They are not especially easy to integrate because of their interactions with propulsion and other systems, and a potential loss of strength and stability, but it seems those issues are solvable with good design.

The relative roll and pitch characteristics of both the main ship and small craft can be very different which leads to a high training requirement.


As with the previous example, we should compare this one with each of the potentials roles

Humanitarian Assistance Disaster Response; This design would provide an excellent platform for HADR missions. The lower deck would ordinarily be used for vehicles, pallets and containers, no need to move until after arrival in the mission area. As described above, 60 pickup type vehicles or 20 standard 6×6 cargo trucks and anything in between like engineering plant and logistics vehicles. As a minimum, these could be substituted for 30 TEU, 60 TEU if double stacked. The air operations capability would support helicopter lift and unmanned ISTAR systems like a Scan Eagle or any of the off the shelf mapping systems widely available. At maximum capacity, and leaving no room for boats or modules but taking into account turning circles, RORO ramps and other fittings, the main deck has approximately 400 lane metres, approximately 30 6×6 trucks, each with a 20ft ISO container. A Mexeflote could be carried disassembled on the main deck and unloaded using the telescopic gantry systems or deck crane. There would be an argument to design in some ‘open deck’ space to make this easier. If not a Mexeflote, the space and lifting capacity of the handling system would allow a landing craft to be embarked. With excess accommodation for approximately 60 personnel, the response team would be sufficient. More could be embarked if using modular accommodation units.

Training and Defence Engagement; a lot of space means a lot of training opportunities and unlike the example above, aviation facilities would also allow that to be included in the training matrix.

Maritime and Littoral Security; with a combination of multiple helicopters, UAV’s, RHIBS and larger patrol craft, and even hovercraft, this would be a very good ‘mothership’ 60 additional personnel, again, would be easily carried without reverting to modules and the ample space on the main deck would allow any small craft to be hangared and maintained for long periods. There would also be ample space for prisoner facilities. The extensive ROV and offboard system handling, including dive facilities and a large moonpool, would make this an excellent platform for submarine cable and infrastructure security and support.

Medical Support; Like the first example, I remain to be convinced that the main deck could be used for a Role 3 hospital facility without a permanent conversion but if that were accepted, it would be an excellent platform, whilst still retaining some capacity for the other roles.

Salvage, Repair and Fire Fighting; by retaining the large crane, using a modular workshop facility (similar to those used in the land environment) and modular diver support system, it would provide excellent salvage/repair and submarine tender facilities. There would be an argument that a larger crane and some open deck retention would make for a better capability.

Experimentation and Systems Development; I think it would be taken for granted, that the large open deck, crane, services connectivity and additional accommodation would provide a very good platform for experimentation and systems development, especially emerging unmanned surface vessels and aerial vehicles.

MCM and Survey; same arguments for example 1, but obviously, it would be able to carry considerably more off-board platforms, host emerging uncrewed aerial vehicles in the MCM role, and carry out the MCM command function for larger and/or enduring deployments. Its excess space and excellent handling facilities, coupled with accommodation for many personnel, would make an interesting capability as a whole. For survey tasks, again, the development of off-board systems will be linked to suitability but for basic instruments like bottom profilers and CDT’s, the handling systems should be more than enough, although some open space at the stern and a small A-frame might be best suited.

Ship to Shore Logistics Support; in addition to carrying supplies, vehicles, personnel and engineering plant for port repair, another suitable task would be that of providing a ship to shore fuel transfer capability. It would also be able to carry a lot of supplies in their own right

Special Forces and Intelligence Support; whether carrying raiding craft, small landing craft, vehicles, personnel or even a swimmer delivery vehicle, the carrying capacity and flexibility afforded by the main deck space would provide obvious utility for special forces. Containerised signals equipment could also be used to provide an additional and innocuous capability for gathering intelligence. Unmanned systems would also be potential carries and the aviation capacity would provide another valuable enhancement.

Submarine Rescue; ironically, the lack of open deck space might make it impossible to host the NATO Submarine Rescue System. The acid test is whether the Launch and Recovery System (LARS) could be fitted to the flight deck and operated from there.


This example would be a significant step up from the first; the additional accommodation, aviation facilities and covered main deck, with its flexible handling and launch/recovery systems, really do make the difference in many of the potential roles. It is difficult to estimate costs because like much of this, it would be guesswork, if we start with £65 million starting price and then remove the skidding system, active heave compensated crane and fluid handling, how much would the cost reduce by? We know the PX 121 is going for £20 million to £30 million so that sets the hard stop point, perhaps if we guessed at a reduction of £20 million we would not be far off. If the military comms, additional sensors, aviation facilities and all the cargo deck systems came in at £20-30 million we would not be far off our original target price of £75 million. There may be some discussion on the stern arrangements, whether a boat launching ramp is needed, or if some open space would be desirable to a fully enclosed area for example. As with example 1, will leave you to decide whether it would be money well spent, or whether there is actually a requirement.

Climbing the Fighty Ladder

All through, I have been at pains to avoid adding equipment that puts this concept into the range of tasks that should be conducted by a Frigate, Destroyer or other surface combat vessel. The whole name of this page reinforces this point.

If there is fighting to be done, it would be done by the offboard systems they carry; small craft, embarked forces and helicopters for example. This keeps the cost down. Beyond GPMG and a minigun the examples described, don’t have any other fixed armament, deliberately. These could be augmented with a small detachment of Army or Royal Marines personnel equipped with Javelin ATGW’s and HVM air defence missiles, but the core principle remains.


However, there might be some argument for hardening and ascending the fight ladder.

The first thing to address would be countermeasures. Countermeasures are not often discussed but are advancing all the time and many consider them more effective at protecting against anti-ship missiles than CIWS. A range of active and passive decoys will be deployed depending on the threat. Whilst the physical launch systems may be very low cost, the warning and control components will add cost and complexity. But if we want these to operate in a hazardous area, even with protection from surface combat vessels and aircraft, it may be a reasonable investment that when taken in context, is not actually that big.

To provide a step up from 7.62mm and 12.7mm and fitted to both the Type 45 and Type 23 are MSI 30mm automatic cannon systems. They would certainly provide more firepower than the small calibre weapons and MSI have even proposed a variant called SIGMA with a Thales Lightweight Multirole Missile (LMM) for use against light aircraft, UAV’s and surface targets. UK Phalanx has been variously upgraded, used on trailer mounts for C-RAM in Iraq and Afghanistan and converted back to the maritime role. The latest version is the 1B that upgrades a number of components and adds a visual cueing and tracking system for use against surface targets. 

Beyond this, perhaps adding a Land Ceptor onto the deck might provide some distributed protection if it was cued from offboard. Maybe parking an M/GMLRS on the deck might be appropriate! Where these concepts tend to fall down is the cost of the missile systems and supporting infrastructure tends to dwarf the cost of the platform, so a loss of the platform because it is cheap and cheerful means the loss of the missiles, which are far from cheap and cheerful.

Am not a fan of going beyond very basic self-protection.


The two examples are simply to show the potential span of solutions, from dirt cheap and time-limited to super flexible and more expensive. None of them is the definitive article and I make no claims of being a naval architect, so they are just a few ideas and no more. The examples of actual civilian vessel derived designs and conversions should also provide food for thought.

Are they actually feasible from a design and engineering perspective, again, I really don’t know?

The idea is a simple one, trying to square the circle of defence inflation > budget increases because, at the risk of being a bore, more money isn’t happening short of a major deterioration of the security environment. Whilst holding out for more money we might reflect on something that was also just an idea.

Professor Charles Inglis had an idea for a portable military bridge in 1908, despite no requirement from the Army he would eventually go on to design the various iterations of the Inglis Bridge, without which the Bailey Bridge would simply not have happened.

I don’t claim this concept is a good idea, I don’t claim that it fits any specific requirement but as I am at pains to repeatedly point out, dismissing things is all well and good, as long as people are OK with the idea of a reducing fleet because of our complete and utter failure in containing cost growth in major equipment.

A year or two ago I was roundly pilloried by many for suggesting the RN would not in a million years get 13 Type 26, oh no I was assured, Type 26 is low risk, it will be only £350 million each, we will get 13. So here we are in 2021, let’s just say somewhat less than 13 Type 26, an unspecified number of HMS Jam Tomorrow and a shit load of Offshore Patrol Vessels we don’t actually.

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