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					                             the marine analyst
             SMS Instrumentation for ARM Engineering Study
                                                   by Frederick H. Ashcroft

                               One of the Railbelt Barges Awaits Loading with Rail Cars in Seattle

 I     n support of an on-going engineering study, during Oc-
       tober of 2002 BMT Scientific Marine Services, Inc.
installed six degree of freedom (6DOF) motions measure-
                                                                   port engineer removes the data disk and replaces it with a
                                                                   The removed CF disk is sent to BMT Scientific Marine Ser-
ment packages aboard three barges owned and operated by
                                                                   vices for data archiving and processing. The data is copied
Alaska Railbelt Marine (ARM). In addition, one barge also
                                                                   from the CF disk to a CD-ROM along with all the neces-
had point strain gages installed at eight locations of interest.
                                                                   sary calibration files and processed to make sure that all
These barges operate between Seattle and Alaska carrying
                                                                   sensors are working properly. After verifying that the data
a mix of railroad cars and containers, each barge making
                                                                   has been successfully archived, the CF disk is erased and
one round trip every three weeks.
                                                                   returned to ARM for re-use. The archived data is then pro-
The instrumentation systems consist of three linear acceler-       cessed to provide a detailed look at the barge motions during
ometers and three rotational rate sensors. They are self con-      the voyage. Motions are also translated from the measure-
tained and battery powered. The batteries contain enough           ment location to the nominal barge center of gravity and a
power to operate the system for a normal trip with 50%             number of other locations of interest to ARM. The processed
safety margin. When the barge generators are operating             data is presented as plots in a Voyage Summary Report as
during loading/unloading operations, the battery bank is au-       well as tabulated in comma separated variable (CSV) files.
tomatically recharged. Data from the sensors is filtered and       These reports and files are sent to ARM and their naval
processed using a single board computer and stored on a            architect electronically for review and further analysis in
compact flash (CF) disk similar to those used in many digital      support of an on-going engineering project.
cameras. During the voyage, the crew of the tug maintains
                                                                   For further information regarding vessel instrumentation and
a detailed weather log so that environmental conditions may
                                                                   tow monitoring, please contact Rick Ashcroft at 760-737-
be correlated to measured motions and strains during post
                                                                   3505 or via email to
voyage analysis. At the Seattle end of each voyage, an ARM
                                           President’s Message
                                                       by Frank DeBord

        don’t know where the summer, and in fact the last             challenges for BMT Scientific Marine Services. The staff
 I      year have gone. It seems like several weeks ago when
        we were making preparations for the 2002 SNAME
                                                                      has now grown to thirty-seven and our annual sales volume
                                                                      will exceed $6 million US this year. As a result, we are con-
Annual Meeting and International Maritime Exhibition in               tinuing to recruit quality people, and we are working on im-
Boston. Looking ahead to the San Francisco World Mari-                provements to our infrastructure to insure that we can con-
time Technology Conference in October, I have been thinking           tinue to provide high-quality services to our customers, while
about the changes in our industry and how BMT Scientific              maintaining an attractive and rewarding environment for our
Marine Services, Inc. has evolved over the past thirteen              employees. We are starting the process to become ISO 9000
years. The increasing globalization in our industry, as re-           certified, and we are working with our BMT sister compa-
flected by this upcoming conference, is very evident in our           nies to insure that we take maximum advantage of the geo-
own business. As a subsidiary of British Maritime Technol-            graphic diversification and diverse skills available within the
ogy limited (BMT), we are now part of an organization                 group to more efficiently meet our customers’ needs. In
with offices worldwide, serving most sectors of the inter-            addition, we will soon be announcing a new joint venture
national marine and offshore industries. Our offices in Hous-         with our parent company to provide a wide range of oil and
ton and San Diego are working on projects with activities in          gas consulting services from our Houston office. This ven-
the US, Canada, Europe, Africa, South America, Mexico,                ture will be combined with some internal organizational
and Korea. These projects include services ranging from               changes to insure that we continue to improve our ability to
design and installation of operational shipboard and offshore         service customers in our more traditional business areas of
instrumentations systems, to port and harbor design stud-             specialized Naval Architecture consulting and offshore in-
ies, to completion of at-sea trials and testing, to model test-       strumentation systems.
ing of offshore platform concepts, to design consulting for
                                                                      I am interested in any feedback from existing customers on
America’s Cup racing yachts.
                                                                      how we can improve our services, or how we might better
This geographic and service diversity, combined with the              respond to future needs. Send e-mail to
growth in business volume is providing some significant               or stop by our booth at the World Maritime Technology Con-

         Technical Excellence

C      laudio Fassardi has been awarded the 2003 BMT
       Research & Technology Award for his paper Tank
       Testing and Data Analysis Techniques for the As-
                                                                           Visit our booth at this year’s Society of
sessment of Sailboat Hydrodynamic Characteristics. He                      Naval Architects and Marine Engineers
is the second BMT Scientific Marine Services, Inc. engi-                    (SNAME) annual meeting being held
neer to be recognized among the entire worldwide group of                   concurrently with the World Maritime
BMT companies. Rick Ashcroft received the award in 2002                            Technology Conference.
for his paper, The Prediction of Fatigue Life and Struc-                               October 18 to 20,
tural Management for FPSOs. For information on either
of these papers, contact or
                                                                                      San Francisco, CA                                                                       Booth # 305

the marine analyst—SNAME 2003                                     2
                      Structural Monitoring for RO/RO Ramps
                                                         by Frank DeBord

 I     n January 2003, BMT Scientific Marine Services be-
       gan a project for Mormac Marine Enterprises and the
       U.S. Maritime Administration to develop a prototype
                                                                      The second objective of the prototype development project
                                                                      is to verify that the ramp structural analyses and data pro-
                                                                      cessing procedures used to determine safe vehicle weight
Stern Ramp Structural Monitoring System for the Cape T                limits work properly during actual cargo operations. Install-
Class Ready Reserve Fleet ships. These ships are RO/RO’s              ing a large number of temporary strain gages on the Cape
converted to carry military vehicles, and they have stern             Trinity stern ramp, and several series of trials at the pier
ramps which were originally designed to load and discharge            and in Galveston Bay are being completed to satisfy this
vehicles to a fixed pier. Their mission is such that in the fu-       objective. During these tests, known vehicle weights will be
ture, they may be called on to offload vehicles to floating           driven over the ramp with and without wave excited mo-
causeways or vessels. To insure that these operations can             tions and the relationships between measured motions, prin-
be safely completed, the US Maritime Administration, work-            cipal bending stresses, and stresses at critical locations will
ing with the American Bureau of Shipping, made the deci-              be verified.
sion to develop a real-time monitoring system to insure that
                                                                      At the conclusion of the prototype development project, the
structural loads in the presence of wave motions do not ex-
                                                                      Cape Trinity will have a verified real-time monitoring and
ceed design limits.
                                                                      display system to insure that vehicle operations can be con-
                                                                      ducted safely across the stern ramp in a seaway. In addi-
                                                                      tion, a final design will be available to install similar systems
                                                                      on all ships in the class. For more information, contact

                 M/V Cape Trinity Stern Ramp

Development of the prototype Stern Ramp Structural Moni-
toring System includes two principal objectives. First, an op-
erational strategy and permanent instrumentation system for
monitoring stresses and motions, and displaying safe operat-
ing limits are being developed. The prototype includes direct
measurement of overall ramp bending stresses using long
base strain gages, and ramp motions using vertical acceler-
ometers. These measurements will be processed and safe
vehicle weight limits will be displayed for operators using a
combination of traffic lights and large numeric displays, which
can be seen by personnel at both ends of the ramp as well as
vehicle drivers.
                                                                        Stern Ramp Structural Monitoring System Large Format

                                                                  3                         the marine analyst—SNAME 2003
      Monitoring System for the New Tacoma Narrows Bridge
                                                    by David L. Hankin

A      new bridge is being built to cross the Tacoma Nar-
      rows: The famous site where Galloping Gertie met
      her end in 1940.

       Galloping Gertie as she fell, November 7th 1940

Shortly after Galloping Gertie fell, she was replaced by an-
other bridge, similar in look, but of different construction.
That bridge still stands today.
The new bridge will be owned by the Washington State De-
partment of Transport. It is being designed and built by
Tacoma Narrows Constructors, a joint venture between
Bechtel and Kiewit Pacific.
                                                                     Construction of the new bridge piers continues just 65 feet
                                                                     from the existing bridge piers, in currents reaching 7 knots

                                                                    The single most challenging feature of the project is the
                                                                    massive tidal currents, reaching up to 7 knots, that rip through
                                                                    the Narrows each day.
                                                                    Extensive research has been carried out to predict the loads
                                                                    on the new bridge piers, which for the greater part of their
                                                                    construction will be floating just a short distance from the
                                                                    existing bridge piers.
                                                                    Construction of the piers was started in the nearby Port of
                                                                    Tacoma. When the piers left port they floated with a draft
                                                                    of approximately 45 feet. The water depth where the piers
                                                                    will eventually stand is 150 feet. For the next eight months,
                                                                    construction of the piers will continue while they float in the
                                                                    Narrows just 65 feet away from the existing bridge piers,
                                                                    each held in place by a 32 point mooring system.
          New pier being maneuvered into position

the marine analyst—SNAME 2003                                   4
                                                                               Upstream of the caisson in a 4 knot current

                                                                      The raw signals from these instruments pass through ar-
                                                                      mored cable to nearby junction boxes where they are pro-
Instrumented load pin, used to measure mooring line tensions          cessed.
                                                                      The processed signals are transmitted from junction box to
                                                                      junction box in a daisy chain fashion to minimize the amount
With the existing bridge so close, it is critical that TNC know       of cable run on the scaffold. A single cable passes from
the precise location and attitude of the caisson, and the ten-        each caisson to a monitoring office set up on the pier tops of
sions in each of the 64 mooring lines at all times.                   the existing bridge. For more information, contact
BMT Scientific Marine Services, Inc. is supplying the in-
strumentation system that gathers and displays this vital in-
formation. The system has the following components:
u Load pins to measure the tensions in each of the 64
  mooring lines.
u Real-Time Kinematic (RTK) GPS system with two
  receivers on each caisson to measure caisson position
  and yaw angle. This system outputs both horizontal
  and vertical coordinates for each antenna with sub-
  inch accuracy.
u Caisson attitude, i.e. heel and trim, is measured using a
  submersible biaxial accelerometer device installed in
  one of the caisson dredge wells.
u Caisson dynamic motions, i.e. pitch and roll, are
  measured using a dual-axis vertical reference unit
  installed topsides.
                                                                              How the new bridge will look once completed

                                                                  5                        the marine analyst—SNAME 2003
                                              Inclining Experiments:
                                            Is The Pendulum Becoming Outdated?
                                                     by Simon B. Cooper

I    t has long been a tradition to perform stability or incline
     tests on new or upgraded vessels. Those involved with
     marine vehicles recognize that the stability test is vital
to safe operations of the vessel. Traditionally, this test was
used as a tool to see that the vessel would float the right
way up. Today, it is required by law. However, most incline
tests today are still performed as they were some 50 years
ago. The inclining experiment is a procedure for determin-
ing the height of a vessel’s center of gravity (KG) above the
keel. This is achieved by inclining the vessel using a known
moment. From the induced angle you are able to calculate
the vessel center of gravity (KG). Until the advent of reli-
able instrumentation and signal conditioning, no high-tech
methods had the accuracy or reliability of the traditional
method that utilizes redundant suspended pendulums, until
                                                                               Typical Arrangement of the SMS Inclinometer
For the past few years BMT Scientific Marine Services,                 typical installation is shown in the illustration.
Inc. has been offering support for incline tests. We offer             System History and Development
dual redundant bi-axial angle measurement instrumentation
                                                                       BMT Scientific Marine Services, Inc. has used the incline
and recording hardware. We submit that the tests performed
                                                                       package on many vessels. Over time we have improved the
to date demonstrate that an incline test can be accurately
                                                                       system based on operational experience. We have two main
performed without using manual pendulums.
                                                                       types of applications for the inclinometer:
Our service includes the use of electronic inclinometers that          u Static inclining experiments
use two different technologies to measure the angle. The               u Permanent fixtures on offshore platforms to measure
inclinometers have been used along with the traditional pen-
                                                                         up to 6 degrees of freedom motions (static and
dulums during all contracted inclines. This service was mainly
used by Diamond Offshore Drilling Inc (DODI). DODI has
long seen the benefits of the using the BMT Scientific Ma-             Many of our major clients have long seen the benefits of
rine Services, Inc. incline equipment. DODI has used the               using an electronic inclinometer. The 6 degree of freedom
BMT Scientific Marine Services, Inc. service as a check of             package was developed primarily to measure the dynamic
the validity of the inclines and to have a time series record          motion of ships and offshore platforms. During these early
of the incline should any problems arise during the post-test          trial periods it was established that the measurement accu-
analysis of the incline data.                                          racy, stability and reliability were so great that it could be
System Description
                                                                       used to measure static angles of list and trim during incline
                                                                       tests. BMT Scientific Marine Services, Inc. started to mar-
BMT Scientific Marine Services, Inc. incline equipment                 ket this service and we have generated some interest from
consists of bi-axial pair of orthogonally mounted accelerom-           the offshore community. This interest has been growing within
eters aligned in the vessel to measure list and trim. A bi-            the industry among naval architects and marine engineers.
axial fluiditic inclinometer is the redundant instrument that
                                                                       Advantages of Electronic Inclinometers
also measures list and trim. The sensors are mounted in a
                                                                       u Inertial grade, temperature corrected accelerometers
junction box that measures approximately 1.5 foot long x 1
foot wide x 8 inches deep. The incline equipment can be                    are very stable and accurate
mounted virtually anywhere. In addition to this, the equip-            u   The inclinometer is an accurate, reliable and quickly
ment uses only a power supply and a laptop computer. A                     installed method for measuring the angle

the marine analyst—SNAME 2003                                      6
                                                                          Sea Trials Support for the
                                                                             M/V Midnight Sun
                                                                                      by Frederick H. Ashcroft
u   Redundant instruments are provided to measure the
    inclination in the degree of freedom of interest
u   Redundant, orthogonally mounted instruments allow
    the measurement of cross axis out-of-plane motion, to
    ensure minimal deflections/influence due to cross or
    oblique winds, or cross or oblique currents that affect
    the principle axis measurements
u   Dual redundant instruments are inherent or built-in
    spares (If one axis fails on the principal axis just prior
    to an incline, the box can be rotated and measure-
    ments of the principle axis can be made with the same
u   Less man power needed to run the incline experiment
u   No need to survey the ship for possible locations for
    the pendulums
                                                                         The Sister Ship, M/V North Star Fitting out at NASSCO
u   No oil baths, pendulums, pendulum mounting brack-
    ets, etc. are required if only electronic measurements
    are made                                                               n March 2003, BMT Scientific Marine Services, Inc.
    Ability to filter out environmental influences
    Long term averages allow you to statistically improve
                                                                     I     provided support for NASSCO during the standardiza-
                                                                           tion trials of the new TOTE trailer ship M/V Midnight
    your results                                                     Sun. Support included providing independent wind speed and
                                                                     direction measurements as well as GPS information during
Though not yet accepted by major classification societies as
                                                                     the speed/power and maneuvering portion of the trials. An
the primary method of measuring the incline angle, BMT
                                                                     R. M. Young model 09101-52 Wind Sensor SE and a Trimble
Scientific Marine Services, Inc. believes an effort should be
                                                                     DSM12/212 DGPS were installed on separate masts atop
launched to incorporate the new electronic method into the
                                                                     the deckhouse. These instruments were connected to a
classification society rules to give the vessels owners the
                                                                     laptop based data acquisition system running SMS WinMon
option of using an electronic device to measure the incline
                                                                     data acquisition software. During the trials, data was pro-
angles. BMT Scientific Marine Services, Inc. aims to be
                                                                     cessed using DATMAT to ensure that performance was as
able to measure the angle using three devices each with
                                                                     expected and that the trial goals were being met. After the
dual axis sensors, thus giving the system triple redundancy.
                                                                     trials, the data was post processed to provide detailed plots
This may in turn replace the present methodology that uses
                                                                     of each recorded test run for the NASSCO trials report.
triple redundant pendulums.
                                                                     In addition, BMT Scientific Marine Services, Inc. personnel
For more information about this service, contact Simon
                                                                     provided support for the local vibration study, assisting with
Cooper,, or Tom Johnson,
                                                                     the measurements and discussion of the preliminary results., at 281-858-8090.
                                                                     For more information on support of sea trials and special
                                                                     studies, please contact Rick Ashcroft at 760-737-3505 or
                                                                     via email to

                                                                 7                        the marine analyst—SNAME 2003
                            Staff Additions
                    Theresa Hovde        Mariann Lewis
                    recently joined      joined our Hous-
                    our Administra-      ton office in July
                    tive team in our     of this year as a                        BMT Scientific Marine
                    California office.   part-time recep-                            Services, Inc.
                    Her previous ex-     tionist. She has                         BMT SMS serves the interna-
perience with data entry and process-    been a contractor for BMT SMS over          tional marine and offshore
ing, accounts payable and accounting     the years, and we welcome her now       industries by delivering practical
management is a welcome asset in our     as a staff member and team player.        solutions to challenging engi-
continued growth.                                                                     neering problems through
                                                                                  specialized consulting, custom-
                                                                                    ized system integration and
                  Upcoming Conferences                                           instrumentation systems, testing,
                                                                                   data analysis, and reporting.
          lease visit us at these conferences to discuss any projects we have
  P       mentioned, or any challenges that we may be of assistance in working
          with you to resolve.
                                                                                        101 State Place - Suite N
                                                                                         Escondido, CA 92029
World Maritime Technology Conference/Society of Naval Architects and                     Phone: (760) 737-3505
                                                                                          Fax: (760) 737-0232
Marine Engineers (SNAME):
                                                                                         9835B Whithorn Drive
October 18 to 20, San Francisco, CA      Booth # 305                                      Houston, TX 77095
                                                                                         Phone: (281) 858-8090
Deep Oil Technology:                                                                      Fax: (281) 858-8898
November 19th to 21st, Marseille, France                                                7614 Thanksgiving Road
                                                                                           Easton, MD 21601
Workboat:                                                                                Phone: (410) 763-8371
                                                                                          Fax: (410) 763-8854
December 3rd to 5th, New Orleans, LA            Booth #2007

BMT Scientific Marine Services, Inc.
101 State Place - Suite N
Escondido, CA 92029

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       See us at Booth # 305                                   Pre

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