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At-Sea Cable Lay Monitoring & Control System - An Introduction |
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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. |
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MakaiLay Functions:
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:
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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.
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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.
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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.
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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.
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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.
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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.
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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. |
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How MakaiLay Works... |
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.

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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.
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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.
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MakaiLay: Real-Time Monitoring |
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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:
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When
placing a cable with slack on the seafloor
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When
placing a cable with tension on the seafloor
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When
deploying in-line cable bodies on a cable with bottom slack or tension
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When
stopping and restarting a cable lay
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When
recovering a cable
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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.

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MakaiLay: Real-Time Control |
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The Control Opportunity:
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.

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MakaiLay: Simulation |
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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:
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Understanding
how a cable will behave under certain conditions.
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Determine
whether a cable can be installed using specific equipment or with a
specific installation plan.
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Train cable
operators by showing them exactly what the cable will do under specific
ship and cable payout instructions
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Create
detailed Ship Plans in advance of a cable lay
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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.

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MakaiLay: Hardware |
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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:
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Pentium III,
double processor, 1.26 GHz, with 1 GB RAM (RDRAM)
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Two, 21”
monitors
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Graphic card
with 32 MB (dual monitor capable)
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Recommend
four each, 9GB SCSI drives, RAID Configured
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Microsoft
Windows 2000 Professional or Windows XP Professional
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Keyboard and
mouse
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3.5” 1.44 MB
Floppy Drive
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CD ROM
Read/Write
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PCI
Rocketport serial card (32 ports)
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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. |
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MakaiLay: Program Validation |
Makai Ocean
Engineering has strived for excellence in understanding, analyzing, and
performing submarine cable installations. We have been working on
submarine cable projects since 1983 and formally created our Cable
Division in 1988. Since that time, we have been involved in a variety of
difficult cable installations, each of which has challenged, expanded
and tested our capabilities. This section summarizes a few of those
difficult cable lays in order to illustrate the capabilities of MakaiLay
and Makai.
The
following three cable installations describe the conditions under which
MakaiLay was initially developed and the performance that is possible
for:
Precision Calibration:
Hawaii Deep Water Cable
The Hawaii
Deep Water Cable Program (HDWCP) was a research and development program
co-sponsored by the U.S. Department of Energy and the State of Hawaii.
The purpose of this program was to determine the technical feasibility
of deploying and operating a submarine power transmission cable between
the Island of Hawaii and the Island of Oahu. This project posed unique
challenges never encountered by any previously laid power cable:
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The
cable route depth was 1920m maximum, almost four times deeper than
any previous power cable installation
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Bottom
slopes were as high as 44 degrees
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Sea
conditions were difficult; winds of 35 knots 35% of the time, 8 ft
seas and surface currents of 2.9 knots.
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Because of
the difficult bottom conditions, the acceptable cable path was quite
narrow. The cable had to be laid to an accuracy of
±12
meters. Furthermore, the cable had to be laid at a very slight
positive tension, no slack.
Makai
coordinated and directed the route survey across the Alenuihaha Channel.
We quickly determined that conventional cable laying techniques were
not suitable due to the difficulty of the cable route and the accuracy
required. It was necessary to have a better analytical understanding
of the cable laying process.
Makai
developed a detailed analytical model that was sufficiently fast and
sufficiently accurate to simulate, analyze and eventually form the heart
of a real-time control system to lay this power cable.
In 1989, a
test cable was laid along the Alenuihaha channel cable route. The cable
was laid and recovered three times. This program was a precise test of
the ability to lay cable. A long-base acoustic navigation grid was
established on the seabed and transponders were attached to the cable to
track its progress while laying. As-installed cable positions were
measured within one meter. A manned submersible was used to inspect the
cable on the seabed and to measure as-laid cable tension.
Makai’s
Integrated Control System guided the cable ship (Flexservice III) and
directed the cable payout. Cable solutions were computed in real time
each minute and instructions issued every five minutes. Current profiles
were measured with an ADCP and incorporated into the solution.
The final
result was that the RMS error for all portions of the 20 km of cable
laid was 4.7 meters, considerably less than the 12 m goal. Bottom cable
tension tolerances were equally well met.
This
program demonstrated that cable lays could be carefully controlled with
the use of the proper analytical tools incorporated into the control
system. This program also validated the mathematical code used in those
controls.
Precision Calibration: SOAR-2
In 1990,
after the successful completion of the HDWCP, Makai Ocean Engineering
Inc. was contracted by the U.S. Navy, Naval Facilities Engineering
Command (Chesapeake Division), for the installation of the Phase II of
the Southern California Anti-Submarine Warfare Range (SOAR II). The
SOAR II project involved the deployment of a total of eight, 40-mile
long cables, each having 8 hydrophones and several repeaters. The cable
lay took place in maximum water depths of 1,800 m, off San Clemente
Island in California. The goal was to lay the hydrophones on targets
(specific X and Y locations on the bottom) along cable paths with
multiple abrupt turns. The maximum allowable error at the bottom was 90
meters. In this case, the cable not only had to follow a pre-determined
path, but the bottom cable slack had to be carefully controlled in
order to hit the targets.
Makai made
several modifications to our software to accommodate lightweight
cables, slack conditions, bodies (repeaters, transponders,
hydrophones, etc.) attached to the cable, and a high degree of control
on bottom cable slack.
During the
cable lay Makai provided instructions to the ship and the cable engines
every five minutes and stayed fully in control of the lay even during
unplanned stops and severe changes in currents.
The
project was very successful and a fully functional surveillance range is
now in place. According to an independent survey completed by the
U.S. Navy, the mean value of the hydrophone location from the target
center was 46 m, half the maximum allowable error.
One of the
most valuable services provided by Makai to the Navy was the pre-lay
simulation and analysis (with the forerunner of MakaiPlan Pro). Makai
was able to provide a shopping list to the Navy showing the equipment
(and cost) required vs. performance expected, based on detailed modeling
of the actual installation. The final results were slightly better than
Makai’s predictions.
In
summary, a cable slightly lighter than today’s lightweight
telecommunication cable was deployed while measuring currents, and the
average placement accuracy was 3.5 percent of water depth.
Precision
Calibration:
AURA - Acoustic Underwater Range in Australia
This
project involved the use of a "ship of opportunity" to lay three cables,
each 210 km long, in waters ranging from 10 m to 4,200 m deep. These
cables contained several in-line hydrophones that had to be placed on
specific targets along a preestablished route. In 1992, Makai’s
simulator was used to determine: (a) the placement accuracy expected for
a specific set of cable laying equipment and oceanographic conditions,
and (b) the degree of cable slack control that could be achieved to
minimize the total length of cable used and to avoid the use of
additional expensive repeaters. In 1994, Makai’s software was used to
accurately place the hydrophones off SW Australia.
A
post deployment survey completed by the Navy determined that the final
average placement error for the hydrophones was within
2% of the
values predicted by previous simulations run with the Makai Simulator
under deployment conditions. Despite using a "ship of opportunity" with
poor sea keeping capabilities in high sea states, the use of Makai’s
at-sea control software allowed the cable layer to accurately control
the placement of one of the cable systems in sea states 6-7 (sustained
winds of 30 knots, 10 ft swells and 8 ft seas).
The
absolute level of placement accuracy was 11% of water depth. Currents
were not measured and were not incorporated into the control system.
Cable weights were lighter than conventional lightweight cables used
today and the hydrophones were equivalent in weight to modern cable
splices. Installation speeds varied from 2 to 5 knots.
During
this installation, the control system also demonstrated that it could
accurately control the cable deployment at ship speeds of 5 knots in
depths of water of only 60 m.
Cross-Model Validation:
Makai has
also modeled for the US Navy the installation of micro cables 2 to 4 mm
in diameter with multiple hydrophones. This is an extremely complex,
numerically sensitive, and computationally challenging simulation. The
Navy compared our results with Navy at-sea test results and the best
software programs available in the US Navy. Our solutions had similar or
better accuracy and Makai’s solutions were computed at many hundreds of
times faster than any competitive software.

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:
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Hawaii Deep Water Cable Program
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SOAR II (8 segments) - US Navy
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RANSTAR (3 segments) - Royal Australian Navy
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NTT – (8 separate Lays): Sagami, Izu, etc.
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JASURAUS
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PTS Bahamas - US Navy
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Gemini South and Gemini North
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Southern Cross (3 separate legs)
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Japan USA (3 separate legs)
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Hibernia (Segment E)
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TGN North & TGN Pacific Japan - US
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FLAG Atlantic
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SAT-3
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Apollo North and South
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C2C
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Far Ice Scotland - Iceland
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Med Nautilus Seg 9
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SMW-4
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FALCON
MakaiLay Owners:
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