Increment 2 – Requirements
Building on Increment 1, Increment 2 addresses the second objective;
Be able to exploit a wider range of coastal terrain than just beaches where port access is not practicable and significantly increase the throughput compared to existing solutions.
As described in the ‘making a case for change’ section, the trend towards shoreline development and urbanisation of the littoral environment means the world is running out of beaches suitable for amphibious assault. This won’t happen overnight but the direction of travel is clear.
Although we might initially look at increasing aviation assets, prepositioning equipment, investing in intra-theatre transport vessels or even buying lots and lots of hovercraft, these are not without issues. Improvements in any of these do not exclude development elsewhere and elsewhere is where Increment 2 will focus.
Increment 2 is a great deal more ambitious than 1 because, in a nutshell, it is a concept for a modern day Mulberry.
Piers for use on beaches – except this time, it is beaches plus a load of other terrain.
Mulberry was a masterpiece of military engineering but whilst the design was in many ways visionary, it was not without faults. The US Navy and Army picked up the baton and created the Elevated Causeway (ELCAS) as a component of the wider Joint Logistics Over The Shore (JLOTS) capability, but again, this is limited. Since then there have been a handful of studies aimed at improving the concept of an expeditionary harbour but they have not resulted in any tangible improvements.
Instead, the West has concentrated, arguably correctly, on the amphibious assault phase whilst seeking solutions that avoided shore lodgements and staged everything from the seabase far off shore. The utility and efficacy of the sea basing concept coupled with ship to objective manoeuvre is subject to endless debate but at its core, I am not sure the problem of ‘tonnage’ has been adequately addressed.
The reason STOM/OMFTS/Seabasing evolved was because of the real threat of so-called ‘anti-access’ capabilities proliferating in likely future operating areas. Having a modern Mulberry does not suddenly make that problem go away so this might not address the issue completely.
Instead, it would create a compromise between the two, a balance of risk.
Ships would still need to come into the shore but instead of hanging around for a long time whilst unloading to lighters, and thus vulnerable to discovery and targeting, they would unload in very short order. This rapid unloading will allow combat power and logistics provision to be built up quickly.
By utilising a greater range of terrain, the element of predictability is reduced. Instead of offloading at suitable beaches, which as I described above, are likely to dramatically reduce in number as urbanisation and population-driven changes in land use put coastlines under development pressure, almost any coastal terrain can be exploited.
Both these will reduce risk; shorter times for offloading and greater terrain utilisation, at a cost that is a fraction of that needed for a true over horizon capability.
And that is the essence of Increment 2.
Various solutions exist to make bare beaches less compromised but they are generally characterised by cost and low throughput as a result of double or triple handling cargo onto lighterage or landing craft.
Because these bare beach solutions generally exclude any means of wave attenuation they are restricted by sea state and getting supplies onto lighters or landing craft is also a challenge in the rough stuff.
The existing approach is very much limited by the view that only these two environments equipped, a deep water port that can be easily defended OR a beach that is ‘logistically challenged’
Increment 2 provides an ability to carry out a ship to shore logistics operation in varied terrain and at higher sea states than currently with a much higher throughput derived from cutting out the lighterage middle man and avoiding operations in the surf zone of a beach.
The surf zone is a very difficult environment for cargo and vehicle transfer; if the ground is too soft, handling equipment will bog in, too shallow a beach gradient means lighters and landing craft will run aground in the surf zone and steeper gradients are often accompanied by stronger currents.
Rocky or coral seabed conditions can cause problems for dracones or pipelines.
The requirements are relatively simple.
Capacity and Throughput
At the most basic level, Increment 2 must be able to accommodate a single ship at a time and that ship type should include ROPAX ferries, container feeder vessels, large CONRO’s, the UK’s Strategic RORO vessels, RN and RFA vessels, product tankers; container barges and allied shipping such as the US LMSR vessels.
Mixed passenger and vehicles, usually on short sea routes and includes a wide variety of designs. The image below shows the Canadian MS Chi-Cheemaun, a 7,000 tonne vessel with a bow visor vehicle ramp and 650 passenger capacity. It is typical of the type and has a draught of a touch under 4m.
This combines container holds with roll on roll off vehicle decks, an example of which was the Atlantic Conveyor owned by the Atlantic Container Line. The Atlantic Compass in the image below is a large G3 Class vessel with a design draught of 9.75m but can carry over 3,000 twenty foot containers and a thousand small vehicles.
It is unlikely that a short term port restoration mission would be hosting the large Maersk E Class type of container ships but there are many smaller feeder container ships, usually between 500 and 3,000 TEU. The image below shows the Samskip Endeavour from Damen. It can carry 804 TEU’s and has a draught of 7.33m
Carrying only vehicles and containers these are a common type of vessel and the UK’s Strategic RORO vessels are a good example. The Point class are of a Flensburger CONRO 220 design of 14,200 gross tonnage with capacity of 2,650 lane metres. It has a draught of 7.6m
Bulk fuel can be landed in ISO Tank Containers, wheeled tankers or pumped ashore using flexible pipelines so refined fuel tankers may not form a large part of the inbound shipping into a rehabilitated port but they are included here for completeness. To distinguish them from crude oil tankers they are called Product Tankers, having stainless steel or coated holds with segregated pumping arrangements. Sizes can vary but the Medium Range and coastal types are most common. The image below shows the Stena Caribbean, built by FKAB, with a gross tonnage of just under 8,600 tonnes and a draught of 6.5m
Coastal and oceanic barges are used extensively for container transport in conjunction with tugs. Sizes vary considerably with the larger types are ocean going with double or triple decks for roll on roll off trailers. The image below shows the Crowley El Morro that has a draught of less than 4m.
The US Military Sealift Command (MSC) RORO/Container ship is a good example of a strategic sea-lift vessel that could be used in a port rehabilitation scenario. The USNS Redcloud shown below is is typical of the type with a draught of 10.4m
The US MSC Joint High Speed Vessel is based on a high speed catamaran ferry used for short distance routes. Besides its high speed, one of the principal selling points for this type of vessel is the shallow draught at 3.8m.
Although the whole point of a landing platform type amphibious vessel is to be able to ignore ports it would still be useful if it could make use of a port. The Bay class Landing Platform Dock (Auxiliary) has a draught of 5.8m
This is the same range of vessels as defined in the requirements for Increment 1.
Build Time and Operations Duration
The basic system must be built and trafficking cargo within 48 hours of construction start although for extra-long causeways this may be extended.
Throughput will depend on many factors; the number of ship moves, sea state, type of cargo, and crucially, the ability of the shore location to handle it. However, the target would be to offload any ship within the target types in as little time as practicable. This does sound a little vague, granted, but there is some degree of ‘chicken and egg’ here with the throughput achieved with different design combinations that may be practical, or not.
The systems should be operable for a minimum of 90 days.
The ship interface must be able to accommodate a single RORO, Container or general cargo vessel at low water (including any in-service ships) directly, allowing them to offload without the aid of lighters. The component must include appropriate cranes and offload platforms, lighting and mooring systems
An optional interface may be bulk fuel, in addition to vehicles, containers and general cargo.
The ship interface must be stable, not affected by wave and tide.
The link causeway is the connecting roadway from the ship interface to the shore interface.
It may be floating or fixed but must be able to accommodate MLC120 class loads in single lane configuration with a twin lane configuration as a desirable option.
Because the shore is more than a gently sloping sandy beach in the Increment 2 requirement set the shore interface must be able to connect the pier to a variety of shore terrain.
Images below are representative examples of the type of terrain the shore interface must be able to work with.
Non Beach Shoreline
This shore terrain must also include ports that may have been damaged beyond rapid repair by Increment 1.
Ports and Marinas
The nearshore environment is both complex and challenging.
It is into this environment that Increment 2 will be placed and therefore has to operate.
Temperature Variation; although subsurface temperature variation is not as significant as offshore, any equipment must be able to work across typical temperature variations from the arctic to the tropics. In the arctic, air temperatures can be lower than those underwater.
Wind; wind velocities can often be the determining factor in nearshore operations, especially those involving cargo transfer and berthing activities.
Marine Growth; water chemistry will have a long term effect on marine construction but for the shorter term, marine organism growth will need to be considered.
Current; Tidal currents are not only horizontal but also have a vertical component and they may be channelled by subsurface features. Tide induced currents may also lag the prevailing tide so in some circumstances, the surface current will flow in a different direction to the subsurface current, exacerbated by changes in salinity in estuaries. Currents around structures can create eddies resulting in scour and erosion.
Waves and Swell; waves cause floating structures to move in six degrees.
Consideration of wave loading is likely to be the major factor for Increment 2 design.
For most potential operation locations wave and swell prediction is well established, based on many years of observation. Wave energy is proportional to the square of its height and long wave periodicity can cause many problems where vessels are less than half a wavelength.
Waves are thus characterised by significant height and significant period.
Sea State is a simplification of a very complex subject.
Sea State is a combined measure of wave conditions whose components are local wind generated waves and swell, or waves that have travelled from outside of the local area. Sea State is manifested in three properties, wave height, wave period and wave direction. Wave height is the difference between the crest and trough, period, the time between successive crests and direction from which the wave arrives. These are aggregated over a period of time to produce a simple guide to aid understanding
The build phase should be carried out in Sea State 3 and the completed system operable in Sea State 4, with comparable wind and tidal variations.
Scour; Scour can undermine foundations and spud legs leading to collapse.
When scour has occurred the structure can be subject to wave induced ‘rocking’, total collapse in these conditions is a real threat. Scour from tugs, bow thrusters and waterjet propulsion devices should also be considered for Increment 2.
Soil and Seabed Condition; Because Increment 2 may utilise structures connected to the seabed the condition of the seabed is of critical importance. It may consist of combinations of sands of varying types and size, cobbles, clays, coral, gravel and large boulders.
It is recognised that most solutions to Increment 2 will require some form of dedicated transport and that taking up space on existing amphibious and general cargo vessels is undesirable.
A high level of automation is a general requirement in order to reduce manpower requirements and thus keep through life costs and manning manageable.
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