At-Sea Cable Lay Monitoring & Control System - An Introduction

MakaiLay is a comprehensive PC-based software program designed specifically to install submarine cables with the highest level of accuracy and reliability possible today. Described are the features of MakaiLay, how it works, and details on its validation and testing.

MakaiPlan Pro:  MakaiPlan Pro allows the user to perform powerful and precise 3-D, dynamic simulations of a submarine cable installation. Using the 3-D simulator, the installer can quickly simulate an entire cable lay in advance and in his office. By simulating the installation in detail at 15 to 30 times faster than real-time, a complete lay can be completed in one to two days. The simulation provided by MakaiPlan Pro gives a detailed understanding of cable behavior, can be used for training cable engineers, can be used for pre-lay and post-lay analysis, and can be used to create a detailed Ship Plan for installation. A detailed simulation is valuable to best understand and plan for dynamic cable situations. If used before a cable lay, the simulation is a thorough advance check; errors can be corrected before they become at-sea mistakes.

MakaiLay:  Makai Lay extends the features of MakaiPlan Pro to a practical at-sea working system to accurately manage and control the installation of the submarine cable. The major emphasis in the development of MakaiLay has been in the accuracy and reliability of installing the cable on the seabed as specified by the cable route plan. MakaiLay is the primary subject of this brochure.

MakaiLay is a single comprehensive program that runs on a PC under a Windows-2000/XP operating system. MakaiLay provides the following functions in the cable installation process:

• Planning:  MakaiLay incorporates most of the features of MakaiPlan Pro. It works in a powerful Geographical Information System (GIS), and the user can easily display and accurately contrast geographical-based data. The cable route can be readily viewed as geographical entities properly positioned on navigation charts, route survey data or other GIS data. The user can create and edit a Ship Plan.

• Simulating:  The heart of MakaiLay is a detailed and rigorous 3-D dynamic model of the cable as it is being deployed on the seabed. MakaiLay can be used at any time to simulate a cable lay in detail. Simulation is extremely valuable to visualize exactly what is going to happen to the cable during any installation. It can be used for planning dynamic at-sea operations and for training cable operations personnel.

• Data Logging:  MakaiLay logs all data critical to the cable installation and can log any other available digital data as well. MakaiLay creates a very complete and detailed record of the cable operation.

• Monitoring:  MakaiLay computes accurately and in real-time the shape of the cable between the ship and the seabed and computes a reliable record of touchdown conditions. At all times, the operator knows what the cable is doing and the impact of any ship or cable payout operation on cable touchdown conditions. MakaiLay shows detailed 3-D graphics of the current and past cable shapes.

• Navigating:  MakaiLay can guide the ship along the Ship Plan by working directly with a DP system or by displaying guidance to the helmsman. The navigation display provides ship guidance information and optionally shows any or all other related information in a GIS environment.

• Controlling: MakaiLay is quite flexible in its options for controlling cable payout and ship course and speed. MakaiLay contains the most powerful algorithms available today for controlling seabed slack, tension and/or position.

• Reporting:  MakaiLay provides extensive documentation on the cable lay both in detailed data logs and in GIS as-laid databases. Data retrieval, display and compatibility with other programs are very flexible. As-laid user-configured charts, tables, 3-D images and summaries can be retrieved at any time during the lay by either the main computer or by remote stations throughout the ship. MakaiLay distributes data as needed to client computers located anywhere on the ship.

MakaiLay Creators:

The Cable Division at Makai has 18 years of experience dedicated to the development and use of software for the precise control of submarine cable installations. Makai’s team has taken on challenging cable installations that would be impossible to install with conventional cable-laying techniques. While responding to these challenges, Makai’s cable experts recognized that precise control required a precise understanding of cable behavior and the team developed a tool to provide that understanding.

From this fundamental ability to accurately analyze cable behavior, Makai has developed a complete system for simulating, logging, navigating, monitoring, controlling, editing and documenting a cable operation. MakaiLay is the second generation of software used by Makai for at-sea cable control.

The cable team at Makai consists of professional engineers/programmers dedicated to quality and accuracy. All of our team leaders have extensive at-sea experience on cable ships and know very well both the theoretical and practical side of cable laying.

First, it is important to understand that the primary purpose of a cable management system is to assist in placing the cable on the seabed. The installer is responsible to lay the cable along a given path at a designated level of bottom slack, safely and in a minimum amount of time. While he can easily control the ship end of the cable, he is ultimately responsible for the other end. What happens with the cable between the ship and the seabed is the major unknown in cable laying. No matter how simple or complex, all cable payout methodologies incorporate some method of describing the cable shape between the ship and the seafloor. The degree of success or failure is directly related to the ability to adequately compute cable touchdown conditions.

All cable control systems have the ability to compute cable “shapes” and use those shapes in controlling cable payout or slack. Various methods of computing cable shapes can, at first glance, look identical. However, cable shape computation is a complex issue. Cable shapes are computed based on numerical models. Concepts such as “real-time”, “dynamic”, and “3D” can be quite casually used. The real test of the quality of the numerical model is how rigorous it is in computing cable shapes. A good model will predict behavior that matches well with a real cable.

For the past 40 years, many cable models have been developed based on an adaptation of steady-state cable principals developed by E.E. Zajac of Bell Labs in 1957. Zajac did a fantastic job at defining steady-state cable physics, but his approach was limited by the computing restrictions of his day. Zajac solutions are simple to understand, simple to visualize (defined by cable angle) and have been used by cable engineers for years. Because they are based on steady-state principles, these models are fundamentally prohibited from rigorously computing cable shapes that are non-steady – a common occurrence during cable lays. Today, thanks to the digital computer, we no longer need to make these approximations.

Cable installations are non-steady for roughly between 50% and 100% of the laying time. Cables are non-steady if their shapes vary over time, and this will occur under a variety of conditions. The ship speed often varies, cable payout is not always steady, the course is not always straight, and the cable catenary often contains sensors, repeaters, and splices. An accurate model that can handle unsteady solutions is therefore needed for much of the cable lay.

The heart of MakaiLay is a very thorough and rigorous mathematical model of the cable located between the ship and the seabed. Makai’s model is dynamic, three-dimensional, fast and rigorously adheres to the principles of cable physics. If the MakaiLay input data are correct, the computed cable shape is extremely accurate – under any conditions.

MakaiLay does not distinguish between steady state and transient conditions. The MakaiLay model treats all solutions identically and can compute the proper shape under any condition. The fundamental static and dynamic physics is contained in the model, so the analysis does not change under dynamic conditions and the accuracy remains steady. There is no need for concepts such as “transient slack” or manual adjustments for other unsteady situations.

Makai’s cable analysis can compute solutions that are needed during practical cable laying conditions. MakaiLay can easily accommodate currents because they are simply part of the overall physics of the lay. Current data can be measured using an ADCP, and this is used for more challenging cable installations. MakaiLay’s model can also compute cable solutions where there is either bottom slack or bottom tension.  MakaiLay can make a smooth transition from one solution type to the other, just like a real cable.

A very important aspect of cable analysis and modeling is that a real cable is not unstable under dynamic conditions – it smoothly and gracefully follows any dynamic change in the deployment. So, a good model should do the same. If a real cable can’t jump about the seabed, the modeled cable should not jump either – if it does, there is a fundamental error in the model.

Makai’s model shows a continuous cable stepping smoothly through time with end boundary conditions matched and shapes that are physically reasonable based on prior time steps. The smooth nature of the output is a result of proper modeling of the cable lay physics.

MakaiLay monitors the lay and provides real-time feedback of the cable shape and touchdown conditions during the lay. MakaiLay calculates in real-time a cable shape that provides where the cable is being laid, its bottom slack/tension and the location of any attached cable bodies. It interfaces with vessel instrumentation to receive the necessary data to make these calculations.

MakaiLay computes typically every minute the shape of the cable moving through the water column. This is not an approximation or a simplification of the cable shape. It is a detailed and meticulous 3-D cable computation. The mathematics used in this computation are described in the “How MakaiLay Works” section.

Cable shapes in the water column are displayed in three dimensions and the cable slack is computed. If the computed slack goes to zero, the program computes bottom tension. If the tension goes high, the cable on the bottom may be dragged across the seabed (changing prior touchdown locations and slack). The software computes cable shapes under the following conditions:

• When placing a cable with slack on the seafloor

• When placing a cable with tension on the seafloor

• When deploying in-line cable bodies on a cable with bottom slack or tension

• When stopping and restarting a cable lay

• When recovering a cable

• When lowering a cable free end

MakaiLay has the option to incorporate real-time current measurement data into the cable modeling and analysis. Adding accurate currents in some cases improves the cable shape computations and the touchdown predictions.

The monitoring system stores all computed cable shapes, dynamics, and touchdown conditions for each solution generated.  These archival data are sufficiently complete so that an accurate recreation of the entire lay can be performed in a post-lay analysis.  As a minimum, these archival data include: all program input data, all cable solutions and all ship and cable payout instructions.

Incorporated within MakaiLay is the most thorough and accurate analytical cable model available today. MakaiLay can be used to reliably and practically determine the shape of the cable as it is being lowered to the seafloor and to determine touchdown conditions.

By carrying the MakaiLay at-sea analysis one step further, this same mathematical model can be used to determine future cable shapes. Therefore, touchdown conditions in the immediate future can be reasonably predicted by the model. Having such a prediction is like a having a crystal ball – corrections can be made to the installation procedures to avoid undesirable touchdown conditions.

The three touchdown properties most important for cable installation are slack, tension and position. For most telecommunication cables, slack is the most important goal, tension is undesirable (if slack is satisfied, there will be no tension), and position is of secondary importance. For telecommunication cables, MakaiLay is used to predict and direct cable payout such that bottom slack is controlled at the RPL specified levels.

The control loop: Ship data is logged, processed in the MakaiLay model and future touchdown conditions are computed. Instructions are issued to the helmsman and the cable operator.

Power cables are installed with low levels of bottom tension. MakaiLay solutions are equally valid for a cable being laid under bottom tension.

Some cables require accurate placement on the seabed. In these cases, MakaiLay can be used as a real-time control system to direct the ship along an optimal course in order to keep the bottom cable near the desired bottom path.

In other cases, cable operations require a trade-off between placement accuracy and cable operation time. MakaiLay can optimize this trade-off so that the amount of time to install and recover cable is minimized while the operation stays within it’s design specifications.

The section entitled “MakaiLay validation” illustrates several actual cable installations where the control capabilities of MakaiLay were demonstrated.

Why Control?

If a cable installation accurately follows a detailed and proper Ship Plan, why is there a need for real-time control? Basically, no installation ever follows the plan exactly and many deviate dramatically from the original plan. The ship speed is never exactly according to the plan, and cable payout likewise does not follow the plan perfectly. Often, there are unplanned stops and contingency situations that could not have been anticipated. Equipment failures and weather often dictate major variations from the original plan. Once the ship conditions are not as anticipated, how should the cable be handled?

With real-time control and the full power of the MakaiLay model at sea, the correct adjustments to the plan can be easily and reliably made before they become problems. Cable operations can be monitored and reasonably controlled under nearly any real-time condition.

Seafloor Slack Control:

MakaiLay has the ability to control cable payout speed in order to actively control the cable touchdown on the seafloor. MakaiLay uses the 3-D dynamic monitoring algorithms to predict the near-future cable shapes and touchdown conditions. It computes the appropriate cable payout speed and/or ship speed in order to achieve the desired cable touchdown conditions.

The system displays forecasts of the future cable shape profiles and graphs of future touchdown conditions, surface conditions, ship speed, and payout speed.

Seafloor Position Control:

For more advanced cable installations, MakaiLay can be used for position control of the cable. In this case, future forecasts, often looking an hour or more into the future, are used to optimize a set of ship instructions to keep a cable optimally aligned along a bottom path. Simultaneously with position control, MakaiLay provides seabed slack control.

For years, the cable industry harbored the concept that once a cable left the stern of the ship, there was nothing that could be done to control its placement on the seabed. This concept was a direct result of the steady-state cable models that were prevalent at the time. With MakaiLay in simulation mode, the capacity for position control can be quantified for any given installation. Makai has demonstrated real-time position control on several cable installations (see “Makai Lay: Program Validation”). The ability to make informed decisions at sea in response to any situation has dramatic impact on the reliability and accuracy with which cables can be installed.

MakaiLay allows the user to dynamically simulate the complete cable installation (or any portion of it) either before or after the cable installation. The simulator is very valuable for:

• Understanding how a cable will behave under certain conditions.

• Determine whether a cable can be installed using specific equipment or with a specific installation plan.

• Train cable operators by showing them exactly what the cable will do under specific ship and cable payout instructions

• Create detailed Ship Plans in advance of a cable lay

• Perform analysis of a cable installation after it has been completed.

In simulation mode, MakaiLay behaves exactly as it does at sea. Detailed three-dimensional cable solutions are available to the operator.

MakaiLay can simulate cable installations much faster than real time. Depending upon the speed of the computer being used, cable lays can be completed at 15 to 30 times faster than real-time. A 30-day cable lay can therefore be completed in the office after one or two days of simulation. By quickly scanning the graphical GIS output record produced by MakaiLay, the success or failure of the cable placement will be immediately apparent. 

All the main processing of MakaiLay is performed on a single PC computer under a Windows-2000/XP operating system. A fully redundant backup computer operates in parallel. Data logging is done in parallel and cable solutions are computed on both machines simultaneously. The system can switch to the backup at any time.

Makai recommends the following for the main and backup computers: 

• Pentium III, double processor, 1.26 GHz, with 1 GB RAM (RDRAM)

• Two, 21” monitors

• Graphic card with 32 MB (dual monitor capable)

• Recommend four each, 9GB SCSI drives, RAID Configured

• Microsoft Windows 2000 Professional or Windows XP Professional

• Keyboard and mouse

• 3.5” 1.44 MB Floppy Drive

• CD ROM Read/Write

• PCI Rocketport serial card (32 ports)

• jack panel RS232/RS422

MakaiLay is quite flexible in terms of its configuration beyond the main and backup computers.

Input data can be provided via RS232/422/485 or Ethernet connections. MakaiLay’s standard configuration has 32, RS232/422 input ports and more can be added if needed.

Output from MakaiLay goes to the DP equipment and to the cable room – both locations receive instructions from MakaiLay. Those instructions can be sent by a direct wire (in case of automatic control) or via a Makai-driven display at each location (manual control).

There are client computers distributed throughout the ship; any number can be used. Client computers are stand-alone PC’s with the MakaiLay client software. The clients are connected to the main computers via a dedicated Ethernet.

A plotter and printer can also be provided on the LAN.

Precision Calibration: PTS Bahamas

In 1997, Makai served as a subcontractor to the U.S. Naval Warfare Center for the installation of the Portable Tracking System (PTS).  Initially, Makai was contracted to simulate the deployment operation using the Cable Lay Simulator (CLS) to determine the slack control and level of placement accuracy that could be expected during the deployment of the fiber optic cable and 51 in-line hydrophones that made up the cable system. These simulations were also useful to determine appropriate values of deployment speed in order to properly land the hydrophones on their targets even in the areas where abrupt course changes existed.

Other Cable Installations:

Makai’s at-sea cable installation software has been used on numerous commercial lays and other military installations. Among them are:

• Hawaii Deep Water Cable Program

• SOAR II (8 segments) - US Navy

• RANSTAR (3 segments) - Royal Australian Navy

• NTT – (8 separate Lays): Sagami, Izu, etc.

• JASURAUS

• PTS Bahamas - US Navy

• Gemini South and Gemini North

• Southern Cross (3 separate legs)

• Japan USA (3 separate legs)

• Hibernia (Segment E)

• TGN North & TGN Pacific Japan - US

• FLAG Atlantic

• SAT-3

• Apollo North and South

• C2C

• Far Ice Scotland - Iceland

• Med Nautilus Seg 9

• SMW-4

• FALCON

MakaiLay Owners:

Alcatel	5 Vessels
Asean Cableship Ltd.	1 Vessel
CTC Marine Projects Ltd.	1 Vessel
Dockwise	2 Vessels
Elettra	2 Vessels
Global Marine Systems Ltd.	2 Vessels
International Telecom Group	4 Vessels
L3 - Maripro	1 Vessel
Marimex Japan K.K.	1 Vessel
NTT - WEM	1 Vessel
SAIC	2 Vessels
Solstad	2 Vessels
Tyco	3 Vessels
US Navy	1 Vessel

 

For more information and pricing, contact: makailay@makai.com