In the previous section, I described the changing nature of coastlines and the proliferation of ports, and then defined a requirement for the ports, Requirement 2.
Requirement 3 builds on that to address the changing nature of coastlines, and, the speed of traditional methods of establishing a lodgement area on a beach.
This Requirement is certainly more aspirational than the previous two, and it is more a number of thoughts and ideas on potential solutions rather than a firm proposal, the point being, we need to study the options and see how we can exploit modern systems and technologies.
How do you build up supplies onshore for an embarked force?
For liquids, fuel and water, they will either be driven ashore in containers, tankers, bowsers or jerrycans. When risks have been reduced, there are bulk fuel systems that make use of transfer pumps, dracones and storage tanks that allow fuel to transferred, in large quantities, directly from tankers or dracones.
For vehicles, they are driven from amphibious shipping onto landing craft and lighters (e.g. Mexeflote) and then onto the beach.
For dry cargo, pallets or containers, they are either placed onto vehicles (as above), or placed onto the landing craft and lighters using mechanical handling equipment (MHE), transferred to shore, and finally, unloaded at the beach area using more MHE.
What characterises all these is double handling.
Stores, vehicles and liquids all have to moved off big ships and onto small boats at sea, the small boats have to move slowly to the shore, when they offload, and the return to the big ships and do it again.
This is what makes amphibious logistics so slow, cycle time.
Move further offshore and cycle times start to dramatically increase.
Increase speed of landing craft to compensate and the penalty for speed is increased fuel consumption, cost, and generally, reduction in carrying capacity.
The D-Day planners understood this fundamental point, and in the absence of ports, built their own, the Mulberry Harbour system. The absolutely crucial point about Mulberry was it allowed the logistics operation to cut out the landing craft middle man.
Ships docked and offloaded directly.
Although we might initially look at increasing aviation assets, prepositioning equipment, investing in intra-theatre transport vessels or even buying lots and lots of high speed connectors, these are not without obvious issues and as described in the context section, the ability of a Strike Brigade to transit large distances makes an approach from further afield more feasible.
The D Day Mulberry Harbour 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 – Modular (ELCAS – M) as a component of the wider Joint Logistics Over The Shore (JLOTS) capability, but again, this is limited, not least because it relies on a beach environment and still requires stores double handling. 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.
Stores ships still have to hang around waiting for the slow cycle to complete, for example.
We might therefore visualise Requirement 3 as something akin to an improved ELCAS-M/Mulberry; a landing platform connected to the shore that allows ships to transfer stores, fluids and vehicles to shore without landing craft and lighterage.
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 shore 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.
Because the 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 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.
Requirement 3 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.[adrotate group=”1″]
Breaking the requirement down further…
At the most basic level, Requirement 3 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.
These are the same vessels as defined in Requirement 2.
Cargo types will be vehicular, bulk liquids and containers/pallets and the system must include appropriate cranes and offload platforms, lighting and mooring systems.
The ship interface must be stable, not unduly affected by wave and tide.
All these factors will be traded with other other as any conceptual designs emerge, we may have to compromise on throughput in order to satisfy any notional installation time requirement, or we might be able to meet them all.
Link to Shore Causeway
A link roadway will connect the ship interface to the shore interface, this will allow vehicles, cargo handling equipment and bulk liquids to move to the shore without lighterage.
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 stretch option.
The shore interface is a significant departure from existing systems because it sets out to utilise a much broader range of terrain than beaches.
It will provide a link from the Link to Shore Causeway to the shore, specifically, the shore that can be driven off directly.
The images below are representative examples of the type of industrial, port and natural terrain the shore interface must be able to connect to.
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 nearshore environment is both complex and challenging.
It is into this environment that Requirement 3 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 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 Requirement 3 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.[adrotate group=”1″]
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, period and 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 Requirement 3.
Soil and Seabed Condition; Because Requirement 3 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 Requirement 3 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.
To summarise, Requirement 3 calls for a semi-mobile system that will allow a wide variety of ships to offload their cargo directly to a variety of shore terrain and in a range of environmental conditions, in a timely manner.
This will allow a logistics build up and ongoing sustainment to be conducted much quicker than with traditional methods that utilise landing craft and lighterage.
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