Underwater
Technology
Vol 18 No 1
Spring 1992
A Personal View
Subsea Technology – Opportunities
for the Offshore Industry
JRS Morris CBE
Technical Papers
Encouraging Future Young
Scientists – The View from One Research Laboratory
PA Hollow
Abstract:
The Institute of Oceanographic Sciences Deacon Laboratory has
been setting up links with schools to encourage pupils to
consider careers in science and technology.
Initiatives have included school science projects, the supply of
information for teachers, work experience for pupils and the
publication of careers advice. The need for such education
links arose during the late 1980s and this article examines the
background to this. It describes the activities of the
past two years and concludes that although assessment of these
activities is difficult, the potential encouragement to young
scientists is very valuable.
Day-to-Day Impact of Salmon Farming on the Work of the
River Purification Boards
H Smith
Abstract:
This paper is an attempt to clarify the role of the river
purification boards in Scotland and to explain how legal
control of the salmon farming
industry was developed. Estimates are made of the
potential polluting impact of an industry that has grown
dramatically over the last decade. The author also
identifies the pollution pathways arising from the industry, and
differentiates between operations at land-based farms and
floating cage farms. Details are also given of the Clyde
River Purification Board's control policy and the
self-monitoring requirements imposed on fish farming.
Finally, the author makes clear how the self-monitoring required
by the boards relates to the charging schemes levied by all the
boards on all discharges in respect of compliance and
environmental monitoring.
Estimation of Extreme Wave Heights: A Review of Guidance
Issued by the UK Department of Energy
N Hogben & DJT Carter
Abstract:
The paper reviews the guidance on estimation of extreme
wave heights issued by the UK Department of Energy in 1984 and
1990 with emphasis on the derivation, not previously published,
of a key formula quoted but not explained in the 1990 issue.
It considers first the widely used simple approach underlying
the data and associated guidance issued in 1984, and the reasons
for the change to the different presentation based on a more
complex analysis of the 1990 issue. It then explains the
1990 analysis and discusses its implications in terms of a
comparison between the 1984 and 1990 data charts for European
waters. A main finding of the paper is that due to
fortuitous balancing of differences, the simple approach of 1984
and the more complex 1990 methods yield very similar results.
Advanced Power Systems for Autonomous Unmanned Underwater
Vehicles
JG Hawley and GT Reader
Abstract:
The underwater scientific,
commercial and defence communities have long been aware of the
potential uses of unmanned Autonomous Underwater Vehicles (AUVs)
and the development of miniature high capacity computers and
artificial intelligence systems has allowed more ambitious
missions to be considered for such vessels. However, to
carry out these envisaged tasks new power systems will be
required which are superior to those currently used in
non-nuclear underwater vehicles. Existing systems, almost
exclusively, use lead-acid battery driven electric motors and
the energy storage capacity of these systems is only sufficient
for short reach missions. Consequently, alternative power
systems are being developed which make use of advanced
batteries, fuel cells, semi-cells, radioisotopes and non-air
breathing heat engines. This paper details the power
requirements for AUVs, examines the advanced power systems that
are being developed for use in such vessels and describes the
driving forces behind their possible realisation.
Physiological Monitoring by Underwater Ultrasonic
Biotelemetry
B Woodward and R Sh. Habib
Abstract:
Underwater ultrasonic biotelemetry is a branch of underwater
technology concerned with the transmission of physiological
information from a human or animal subject to some remote
receiving station. Here, we consider the transmission,
reception and processing of signals from swimmers and divers,
which includes signal formatting, multiplexing and encoding,
transducers and power amplifiers, power sources, decoding and
data analysis. Applications include monitoring the heart
rate, breathing rate and temperature of a patient in a swimming
pool or a free-swimming diver in open water. The most
challenging problem addressed is how to transmit an
electrocardiogram (ECG) signal in the severe multipath
environment of a swimming pool.
Meeting Reports
Ocean Opportunities – Management for the Future (An address
given at the SUT AGM, 12 December 1991)
Admiral Sir Lindsay Bryson
Advances in Diving Technology to 50 metres—Report on Seminar
M Johnson
Book Reviews
Marine Minerals in Exclusive Economic Zones, by DS Cronan
Reviewed by AJ Smith
Ocean Variability and Acoustic Propagation, by J
Potter and A Warn-Varnas (Eds)
Reviewed by ML Somers
Underwater Technology Vol 18
No 2
Summer 1992
A Personal View
Industry now values collaborative
research
T Veness
Technical Papers
On-Site Tests for Underwater
Video Picture Quality
RW Barrett, M Clarke and B Ray
Abstract:
The majority of underwater operations involve the use of video
for observing and recording. This paper presents the
results of a multi-sponsor project managed by The Marine
Technology Directorate Ltd. The objectives of the project
were to develop a set of test procedures
and quality acceptance thresholds to
ensure that underwater videos shot on site will be fit for their
intended purpose. The tests were designed to be used and
interpreted on site by non-specialist personnel.
Control System Design for High Pressure, High
Temperature, Subsea Control Systems
M Theobald, M Fabbri and D Kirkman
Abstract:
This paper examines the problems associated with subsea control
systems when dealing with high pressures and temperatures.
It offers some overall design consideration to reduce the impact
on umbilicals. Key subsea components such as control
valves and hydraulic connectors are
examined in detail. The authors conclude that existing
design can be modified to withstand foreseeable higher pressures
(up to 150°C). The recommendation is made that long-term
testing is carried out to prove key components.
Downhole and Subsea Completion Design for a High Pressure
North Sea Gas Condensate Field
S Gomersall, K Sardar and G Rae
Abstract:
This paper details the overall system design for a 15,000 psi
subsea, gas condensate well in the North Sea. Currently,
significant industry interest exists
in the technology required to complete wells of this type, which
would enable substantial hydrocarbon reserves to be developed.
Subsea wells such as this have not yet been completed.
Engineering Technology and Aquaculture
MG Poxton
Abstract:
Much of the information currently available on engineering
technology for aquaculture is inadequate, having been
empirically developed on a more or less trial and error basis.
Today, aquaculture remains an art with success largely resulting
from the innate abilities of staff expert at animal husbandry,
practising in open-water systems with good water quality.
The present state of the Atlantic salmon industry in Scotland -
with over-production, low market prices, deterioration in
environmental conditions, disease and many other problems - was
both predictable and predicted. However, this situation
also applies to the production of salmon and other species in
other countries, and is therefore regarded as a ubiquitous
characteristics of the industry. Before this situation can
be improved, scientific and engineering technologies must be
integrated and applied over a wide and diverse area.
Probably no single institute can muster enough resources to
answer all the questions posed by this industry, indeed it
probably would not be cost effective even to try to do so.
Consequently, collaboration is essential between scientists,
engineers, economists and others from a wide range of
institutions, together with the active participation of
industrialists with sufficient financial resources to sustain
long term programmes.
Meeting Reports
Subtech '91—Back to the
Future—Report on Conference
RG Birse, S Cardno and WE Mason
Automation of Remote Subsea Intervention—Report on
Conference
J Turner
High Pressure/High Temperature Subsea Production
Systems—Report on Seminar
GS Bonner
Book Reviews
Business
Fundamentals for Engineers, by Chengi Kuo
Reviewed by RL Allwood
An Introduction to ROV Operations, by G Last and P
Williams
Reviewed by DW Hartley
Underwater Technology Vol 18
No 3
Autumn 1992
A Personal View
Time for a Sea-Change in
Engineering?
Prof JB Caldwell
Technical Papers
The Use of Exploration Geoscience
Data in the Planning and Execution of Site Investigations for
Offshore Development Facilities
MR Cook, JM Square and AW Hill
Abstract:
Prior to development of an offshore hydrocarbon field, large
sums of money are spent by operating companies on the
acquisition and processing of exploration geoscience data.
These data, augmented by other publicly
available data, can be cost-effectively integrated and reviewed
to aid: field development conceptual design; selection of
suitable sites for development facilities; and planning of
detailed, site-specific, geotechnical and geophysical site
investigations. This paper illustrates the range of
geoscience data that normally exists and the uses to which such
data can be put. A case history of two field development
sites in the southern North Sea is presented, to emphasise the
benefits of such a data review and the pitfalls that can occur
if such a review is not undertaken. The benefits of
multi-use of existing data are summarised. Recommendations
are made for future geoscience data acquisition to provide
further information for subsequent field development site
investigations.
SWATH Vessel Engineering Science—State of the Art
Seakeeping
T Downs
Abstract:
Small Waterplane Area Twin Hull (SWATH) ships are
an excellent example of how the physics of fluid flow is being
exploited by naval architects: fluid/body interaction is
engineered to the advantage of the ship. They are a new
breed of advanced ships receiving worthy attention. The
paper provides an overview and introduction to the principles of
why SWATH ships behave as they do and how
engineering scientists use frontier techniques to analyse them
and produce design solutions. The Navatek I, a
Hawaiian passenger cruise vessel launched in 1990, is used as a
case study for the 'state of the art' SWATH ship. The
aspects covered include motions, resistance, stability,
seaworthiness, manoeuvring, structure, safety and missions.
Alternative Methods for Carbon Dioxide Removal in Diving
Life Support Systems
R Hughes, DR Acharya and K Li
Abstract:
The main objective of this
investigation was to develop alternative, more efficient systems
for carbon dioxide removal for diving operations and for small
submersibles. The methods studied included the use of
absorbent liquids supported on porous solids which provided a
regenerable system, and diffusion/permeation processes
including, a) flat sheet membranes, and b) the use of hollow
fibre permeators for gas separations.
Predicting the Fate of Oil Spilt at Sea
MV Leech and MI Walker
Abstract:
Oil spilt at sea has the potential to cause signficant
environmental damage. In order to respond adequately and
minimise such damage, it is essential to respond as quickly as
possible. The physical properties of oil undergo rapid
changes once in the sea and many countermeasures are only useful
for a short period of time before weathering processes make it
difficult to deal with the slick. Oil spill models have
been developed to help speed response and to assist in
pre-planning contingency efforts and training purposes.
Models can rapidly predict the movement, spreading and oil
properties of a slick in the sea, providing advance warning to
the authorities and helping to decide the most appropriate
response. This paper outlines some of the techniques
behind oil spill modelling, concentrating particularly on the
EUROSPILL model. It is important to note that oil spill
models represent an attempt to numerically simulate complex
physical processes and are inevitably limited in their ability
to predict the outcome of actual spills. The quality of
results from a numerical model is strongly influenced by the
quality of the underlying algorithms and the quality of input
data.
A Review of Equipment and Procedures for the 'Lost Bell'
Situation
K Williams
Abstract:
Diving bells are used extensively in
the offshore industry for installation, inspection and
maintenance of underwater structures and equipment. The
most dangerous scenario that can occur involving a bell is when
it is impossible to bring it to the surface, either because the
lifting system is broken or because the bell is trapped.
If the supply of breathing gas or heat from the surface has also
been lost, then this is referred to as the 'Lost Bell
Situation'. This paper briefly looks at the factors which affect
the life expectancy of a diver in this situation, and studies
the current methods of rescue from a lost bell.
Alternative systems, which would reduce the danger to the divers
and prolong their life expectancy are discussed and
recommendations are made to facilitate their implementation.
Meeting Reports
Subsea Control and Data
Acquisition—Report on Conference
R North
A Review of Current Developments in Offshore Ropes—Report
on Conference
RL Allwood
Book Reviews
Water Baby—The Story of Alvin, by Victoria A Kaharl
Reviewed by J Bevan
Tsunami Hazard: A Practical Guide for Tsunami Hazard
Reduction, Ed. EN Bernard
Reviewed by D Pugh
Underwater Technology Vol 18
No 4
Winter 1992
A Personal View
The Pressure to Remain Ignorant
Dr Maurice Cross
Technical Papers
Problems Associated with Seismic
Facies Analysis of Quaternary Sediments in the Northern UK
Continental Shelf
MS Stoker, FS Stewart, MA Paul and D Long
Abstract:
Seismic facies analysis is increasingly
being used in the interpretation of high-resolution seismic
reflection data. Existing depositional systems models,
based primarily on seismic data, have been constructed on the
basis that acoustic character can be directly correlated with
relatively consistent lithologies and geotechnical properties.
However, borehole and shallow core data from the northern UK
continental margin indicate significant inconsistencies in the
use of the technique as a predictive tool. Changes in
acoustic texture can occur laterally and vertically, in both
lithologically homogeneous and heterogeneous sequences.
Conversely, acoustic homogeneity does not necessarily imply a
uniform sedimentary sequence. The successful application
of this technique can only be achieved by the integration of
seismic data with other subsurface information, with
interpretation based on sound geological concepts and models.
Oceanographic Equipment and Instrumentation: needs,
trends and priorities
CP Summerhayes and D Girard
Abstract:
Taking out the effect of inflation, oceanographic ships are now
twice as costly and instrument systems are 10 times as expensive
as they were 20-30 years ago. The trend will continue as
oceanography becomes a global science, and as the proposed
Global Ocean Observing System (GOOS) becomes operational.
The growing requirement from all quarters for knowledge about
the 70% of our planet that is covered by water demands increased
investment in ever more complex and costly measuring systems.
To address the challenges of increased cost and complexity of
operations and equipment, oceanographers must band together
nationally and internationally to ensure that the slim resources
available are used to best effect. Collaboration is
happening through bilateral agreements, through the design of
large scale experiments like WOCE (the World Ocean Circulation
Experiment) and the Ocean Drilling Programme (ODP) and through
the planning of large scale operations, like GOOS.
Collaboration is fostered through the funding of Community
Research Projects nationally, eg, by the Natural Environmental
Research Council (NERC), and internationally, eg, via the CEC's
Marine Science and Technology (MAST) programme. But more
cooperation and better planning is urgently needed at the
international level to reduce the rate of increase of
operational and developmental costs and to get a maximum return
of data and interpretation for the original investments.
High cost systems development is beyond national capabilities
for the most part, requiring international cooperation and
funding. Discussions are needed in international forums (eg,
Pan-European) to develop concensus and plans for collaborative
action.
Evaluation of Hotspot Submarine Hydrothermal
Mineralisation: the example of Pitcairn Island
DS Cronan, RA Hodkinson and O Stoffers
Abstract:
A wide variety of state-of-the-art oceanographic survey,
observation and sampling techniques have been
employed to assess the marine
mineral resource potential of the Pitcairn Island EEZ.
Results show that two large, hot-spot related, shallow submarine
volcanic edifices occur some 80 km east-southeast of Pitcairn
Island. Both are covered by extensive hydrothermal mineral
deposits, with one currently discharging hydrothermal fluids.
Studies suggest that sulphides may be buried just below the
surface of the seamounts. Many of the older seamounts
within the Pitcairn EEZ are covered with relatively thick
hydrogenous Mn-crusts.
Technical Note
High Pressure/High Temperature
Reservoirs—an evaluation of the subsea control system problems
M Theobald and P Turner
Meeting Reports
New Breathing Performance
Standard for the Diving Industry—Report on Seminar
DE Elliott
14th International Congress on Acoustics—Report on
Conference
B Woodward
Book Reviews
Management of Drilling Operations, by Ken Fraser
Reviewed by PA Strong
Dynamics of Fixed Marine Structures (Third Edition),
by NDP Barltrop and AJ Adams
Reviewed by J Witz
