model tests
MARIN JUBILEE MEETING
11-15 May 1992- Wageningen - The Netherlands
PREPRINTS WORKSHOP D NAUTICAL-SIMULATORS
P1992-6D
TECHNISCHE UNIVERSITET taboret:n*10m vaor Scheepshydromechanica ArchlefMekelweg 2,2828 CD Delft
letz 015- 758873 - Fax 015- 781833computations
reality
PREPRINTS WORKSHOP D NAUTICAL SIMULATORS CONTENTS
Session I Research
An Operational Safety Study of a 200m Ro-Ro Newbuilding
through the Herrenbrucke Bridge at the Trave River in Germany M. Heikkild, J. Lethosalo, M Salo (VTT-Tecnical research Centre, Finland) and U. Nienhuis (MARIN, The Netherlands) Manoeuvring Simulation: A Port Planner's Wishes
H. Velsink (Port Advisory Services, The Netherlands)
Simulation as a Vehicle for Co-operation in Port Design and Development
R.L. Tasker (Australian Maritime College, Australia)
The First Step to a Comprehensive Probabilistic Design of the Horizontal Dimensions of Inland Waterways
T. Dijkhuis and H.B. Smits (Rijkswaterstaat, The Netherlands) Challenges for a Competitive MSCN
Th. Elzinga ( Frederic R. Harris, The netherlands)
Session II Research (continued)
Validation: The Ideal and the Real- Some Recent Experiences L.L. Daggett (USAE Waterways Experiment Station, USA)
Models of Manned Ship Operations for the Assesment of Safety P.H. Wewerinke ( University of Twente, The Netherlands) Reception of Large Vessels in the Port of Gijon (Spain)
J.T.M. van Doorn (MSCN, The Netherlands), J.R. Iribarren (Port of Gijon, Spain)
Real Time Photo-Realism with Parallel Visual System Technology A.A.J. Langenkamp (TNO, The Netherlands)
The Smoothing Tracks by Complete Compatibility Reconstruction R. Papenhuyzen (Rijkwaterstaat, The Netherlands)
Session III Nautical Training
On the Training Utililizing the Ship Manoeuvring Simulator -Study on the Evaluation of Training and Learning Process-H. Kobayashi (Tokyo University of Mercantile Marine, Japan) Simulator Training in Integrated Ship Management
M. Harms, Nautical College 'Willem Barentsz' A Seaman's View of Marine Simulation
D. Drown and R. Mercer (MOSTRC, Marine Institute, Canada) Hours of Boredom Interspersed with Moments of Terror H.J. Crooks (Maritime Training and Research Center, Ohio) D.G. Douwsma (Grafton Group, Ohio)
Pilot Simulator Training Development through Identification of Problems in Pilotage
A. Haapio (Rauma Maritime College, Finland)
Session IV Nautical Training (continued)
Nautical training at the Royal Netherlands Naval College: Training Ship and Bridge Simulator as Complements
J.A. Spaans (Royal Netherlands Navy, The Netherlands)
Training Simulations and Crew Evaluation for a New Ferry Type O. Ters10 (Danish Maritime Institute, Denmark)
Optimizing Dual Purpose Training through Dual Purpose Simulation Equipment and Techniques
S.J. Cross (Norcontrol Simulation, Norway)
Maritime Training and Simulators, an Established Combination S. Groenhuis (MSCN, The Netherlands)
Positive and Negative Factors Affecting VTS Simulator Training H. Regelink (Directorate-General Shipping and Maritime
An
Operational
Safety
Study on
a
200
m Ro-Ro
Newbuilding
through the
Herrenbrucke Bridge
at the Trave River
in Germany
M. Heikkila, J.
Lehtosalo, M. Salo
(VTT, Finland)
U. Nienhuis
(MARIN, The Netherlands)
MANOEUVRING SIMULATION: A PORT PLANNER'S WISHES
PROF IR H. VELSINK
Port Advisory Services by, Kalfjeslaan 10, 2623 AH Delft, The Netherlands
In present-day port planning manoeuvring simula-tion is -or should be, except in the very simple and small-scale projects- an important tool to
determine the horizontal dimensions of a port'S approach channel, entrance channel and manoeu-vring space.
This statement presupposes that these horizontal dimensions will be based on an assessment of the risk, in principle in quantitative terms, that they will be exceeded. The acceptable level of risk as such will vary widely from one situation to another, for example due to the nature of the channel banks -flat and muddy or steep and rocky- and due to the type of cargo carried. It may also vary over the length of the channels and manoeuvring area because of differences of consequential damages when exceedance of the physical boundaries results in loss of cargo.
The type of risk that manoeuvring simulation can quantify, or claims to be able to quantify, is the risk that the horizontal boundaries are exceeded due to the inability of the man-machine system -consisting of a ship and its navigator- to cope with a given set of external conditions: currents, waves, wind, visibility and location information. By repeating this exercise for a number of representative vessels and a range of environmental conditions, the an-nual risk can be determined assuming that the density of shipping is known as well as the varia-tion of the environmental condivaria-tions.
This is, in itself, already an elaborate task. It
should be borne in mind, though, that the port planner is ultimately interested in the overall
nauti-cal risk. This overall risk is not caused by
man-machine failures only but also by pure mechanical failure of the ship, by interaction with other traffic, by ship-shore communication failures with VTS systems, and by failure of the passive aids to navi-gation. If the latter group of risk sources were to be dominant, there might be little point in, for example, increasing channel width. The initial effort of risk assessment would, at least, be orient-ed towards investigating to what extent these latter
risks could be reduced by physical and/or
proced-ural measures. However, the present discussion will be mainly restricted to that part of the risk
assessment that should be achieved by manoeuvr-ing simulation.
The question that immediately arises is to what extent present state-of-the-art manoeuvring simula-tors can indeed provide a quantitative risk assess-ment with a desirable level of accuracy, say ±50%. At the lower end of the range of manoeuvrina simulators in existence are the fast-time, or off-line,
simulators. They do not really simulate the
man-machine performance as the navigator is replaced
by a form of autopilot programmed to steer the
ship, in principle along a pre-determined fixed reference track, using data on the physical condi-tions it will encounter in a fixed distance or time period immediately ahead. It thus lacks the human navigator's capability to anticipate in a more general sense and to improvise, whilst it is also not subject to human mis-judgements and errors. It is appreciated that, in the more sophisticated fast-time simulators such as, for example, MARIN's NAVSIM, part of the rigidity of the autopilot has
been overcome. It is possible to introduce random
disturbances in the data input and in the auto-pilot's perceptions and commands, though these are no more than an uncertain approximation of the stochastic behaviour of different parameters in real-fife conditions. One may also assume that further improvements of the fast-time simulation technique will be made, for example by using ex-pert systems to determine, from run to run, a
desired track to be sailed for those prototype
con-ditions where no fixed reference track in the form
of buoys or leading lights exists. However, it is
deemed quite unlikely that a fast-time simulator will ever be able to produce the credible, reasonably accurate quantitative risk analyses mentioned earlier.
This does not mean that the fast-time simulator is
of little use to the port planner. On the contrary, in
the early and intermediate stages of the planning process, it is the only practical tool to test different alternative solutions in a range of physical
condi-tions. As such, any further advances in the
fast-time simulation technique will be definitely welcom-ed.
At the upper end of the manoeuvring simulators are the modern real-time, full-mission simulators of which MSCN's new simulator constitutes a good
example. With the progress made in, amongst
other advances, outside image generation, they enable the study of the total man-machine beha-viour in a probably fairly reliable way. However, the disadvantage of this system is that the time consumption and the costs involved are so high, that severe ,estrictions in the number of sets of physical conditions and the number of simulator runs in each of the sets -usually 10 to 15-, have to be accepted.
This adversely affects the accuracy of the
quantita-tive interpretation of the results. The port planner
is essentially interested in the low to very low fre-quency domain of exceedance of certain physical boundaries. It may be in the order of, say, 1% in case of soft boundaries, but rather 0.1 to 0.01% in case of hard boundaries or dangerous obstacles such as other ships at berth, bounding the manoeuvring zone.
It is recognized that the abandonment of the tradi-tionally assumed normal distribution of recorded sailed paths in a given cross-section, in favour of, for example, a Pearson-type distribution, allows a better fit to flattening and skew of a distribution curve. But, it still does not enable a reliable extra-polation in the low or very low frequency domain to be made. It is, more or less, the same as trying to determine a 1 per 100 years river discharge from a year's discharge measurements.
In addition, the problem of converting the probabi-lity of exceeding the physical boundaries in subse-quent cross-sections into the probability of exceed-ing these boundaries in a full port approach transit,
has not yet been fully solved to my knowledge. In
consequence, one can at least suspect that there is a possibility that major errors may occur in the quantitative interpretation of real-time simulator exercises.
It is, therefore, understandable that from different sides the need has been emphasized for a verifica-tion of these simulator results and predicverifica-tions in comparison with real-life observations. Some years ago, a joint IAPH/PIANC working group was established to conduct such verification. However, this is no easy task because it requires, inter alia, the monitoring and recording -by means of a shore-based trackplotter- of sailed paths of vessels
in a number of existing port approaches over an
extended period of time. These same port
approa-ches, of course, must have been investigated, or will have to be investigated, by real-time
manoeuvr-ing simulation. Probably because of the scope of this task and the costs involved, little has been achieved yet. I understand that, for this reason,
IAPH has decided 'to go it alone'. But it remains
to be seen whether they will have the technical and financial resources to succeed.
In the absence, for the time being, of any serious form of verification one can wonder whether the interpretation of simulator runs through analysis of
'expert opinions' does not result in conclusions
with a similar level of credibility as those obtained by the current practice of over-extrapolating sailed-path distribution curves. It has the advantage that
a lesser number of runs needs to be made per set
of environmental boundary conditions and that, in consequence, a greater range of these conditions
can be incorporated for the same total number of runs. Obtaining and analyzing expert opinions
should preferably be done through Saaty-method questionnaires, as also applied in certain types of
MCA project evaluations. This method allows the
calculation of a consistency index of these opinions, i.e. of the replies to the questions
con-tained in the questionnaires. Subsequently, a
weight factor proportional to the consistency level can be introduced to value the different responses and this will contribute to the confidence in the results obtained.
In between the fast-time simulators on the one hand, and the full-mission real-time simulators like the one that recently started its operations within the Maritime Simulation Centre Netherlands on the other hand, there is quite a variety of intermediate
type real-time simulators. The more sophisticated
ones, in conjunction with the aforementioned analysis by 'expert opinions', will often allow a good feeling of nautical conditions for the full-mission simulator, particularly as they are so much
cheaper to operate. The very simple intermediate type simulators, in my personal opinion, are of no great use for port planning purposes as they fail to
incorporate the human element in the
man-machine system in a convincing way. Due to over-simplifications in the bridge mock-up and limita-tions in -or total absence of- the outside image, the simulator is not able to convey a real-life percep-tion to the navigator. In consequence, it is hard to
draw meaningful conclusions from the results ob-tained.
In summary, it may be observed that, in the
desir-ed range of accuracy, there is no tool yet that
provides the port planner with a quantitative
as-sessment of the risk of a navigator/ship system
exceeding given physical port boundaries. Quantifying the overall nautical risk, i.e. including the dsk of pure mechanical failures, ship-shore communication failures, accidents due to inter-action with other traffic, etc., is even more difficult
an assignment. Since in the 'other' risks, the
would be worthwhile to try to apply a SAGE-type risk analysis technique to this problem.
The SAGE risk analysis and failure avoidance tech-nique incorporates the human factor in a rather exhaustive way. It was initially developed to re-assess the probability of an international launching of ballistic missiles from underground silos in the USA. The conventional risk analysis originally
carried out, centred on mechanical/electrical/
electronic failures, resulted in an extremely low probability which was totally inconsistent with the number of near-mishaps that had already occurred in a relatively short period of time. The SAGE risk analysis technique has since found a wide and varied field of application within the USA, but has received little recognition outside Its frontiers.
In conclusion, it will be clear that there is still a lot
of ground to be covered to make port planners
1. INTRODUCTION
1.1 Simulation Activities
The shiphandling simulator at the Australian Maritime College is used for the training of students in navigation, including shiphandling, as well as for consultancy activities through the entrepreneurial arm of the college, AMC Search Ltd. This joint use of a publicly funded resource is common in Australian uni-versities and institutes of higher education. The consultancy activities in which the sim-ulator has been involved have been confined to the Australasia and Asia Pacific regions. These have included the development and opera-tion of a number of ports and marine facilities, from single berth terminals to much larger installations.
1.2 Scale of Projects
All port development projects involve signific-ant financial outlay. In this rapidly develop-ing region, many projects are, by world stand-ards, small, resulting from the provision of marine facilities for mining or specialised processing activities such as refining.
Decision making is at company level for private capital or semi-government level for publicly funded developments. In both cases, very detailed investigations have to be made and careful submissions prepared to obtain financial approval to proceed with the venture. Sub-missions must convince the 'board of directors'
involved that the development is financially, environmentally and socially sound, that the technical details of the project have been fully investigated and that agreement has been reached by the staff involved on what is the optimum solution.
1.3 Personnel with Direct Involvement
In developing the proposal for 'board' approval, a number of persons from different disciplines
SIMULATION AS A VEHICLE FOR CO-OPERATION IN PORT DESIGN AND DEVELOPMENT
Robert L. TASKER
Australian Maritime College, P.O. Box 986, Launceston, Tasmania, Australia. 7250.
The economics of sea trade create pressures to optimise the use of ships and of port
facilities. All involved in the operation of ships and ports are attempting to maximise
the utilisation of their investments by extending operating parameters, whether they be related to ship size or operating windows. Examples of recent experiences in the use of real-time simulation in close co-operation with those involved, business executives, engineers, operations managers and marine pilots, are examined. These experiences show that the simulator is a unique vehicle for bringing together the professional skills of all those involved and for achieving an outcome which could not readily be achieved were they to approach these problems in isolation.
will be involved. These will range from the chief executive officer to the engineers who will design and build the facility and to the
operations and marine personnel who will run it. In the process there will usually be specialist consultants contracted to provide advice for, or justification of, a proposal. The final proposal would not normally include conflicting views from those involved, although
it may examine various options in coming to its conclusion.
CONFIDENTIALITY
The projects referred to in this paper and in the presentation, although real, are dealt with in the abstract in order to protect the privacy of the parties involved.
OBJECTIVES OF A REAL-TIME SIMULATION STUDY 3.1 Dimensions and Lay-out
Consulting engineers preparing the design will have taken account of PIANC recommendations on channel width, size of swinging basins etc. and will, where appropriate, have validated the design by fast tract simulation. Account will have been taken of the construction com-plexities and costs of different lay-outs. The real-time study will enable those required to use the facility to have significant input and participate in the decision making process. It will enable them to examine the proposal in the context of practical operations which will include those failures of equipment and misjudgments which inevitably occur during the long-term operation of a facility. The con-sequences of such examination may lead to a variation in the design occasioned by the par-ticular features of the operation, the local environment or other factors. Where approp-riate, the examination may lead to a reduction in dimensions and consequent savings in
con-struction costs.
3.2 Berth Arrangements
Using a real-time simulator, an experienced shiphandler will estimate the requirements at the berth such as the spacing and
capabil-ity of fenders. The attitude of the ship
to the berth when berthing and unberthing can be determined and thus, the need for dredg-ing around the berth itself.
3.3 Aids to Navigation
The requirements for visual aids to navigation, such as lead marks, channel marking buoys and beacons and other aids, can readily be deter-mined in real-time simulation. Although not precise, the additional needs for manoeuvring in reduced visibility can also be determined. 3.4 Operating Procedures
Where a new port is being simulated or a new operation for an existing facility, the pre-ferred operational procedures may be determined by real-time simulation. These procedures will vary for different environmental con-ditions, the size and loaded condition of each
ship. These procedures establish operational
guidelines for the introduction of operations in new ports and changes to operational prac-tices in existing ports. They also enable estimates to be made of the time and resources required for such activity.
3.5 Port Admittance Policy
The simulation study will determine the limit-ing environmental conditions under which ship manoeuvres can be conducted. This may include establishing operating windows for tidal con-ditions, wind direction/velocity and visibility. While these limitations may be modified with experience in the operation of the port, they form a valuable baseline from which to commence operations and refine estimations of berth occupancy, queueing needs etc.
3.6 Tug Requirements
Real-time simulation will assist in the determination of needs for tug assistance. This is important, as the lead time between determining requirements for tugs and obtain-ingthe desired type and capacity of tugs can be as long as the construction time of the facility itself.
3.7 Emergency Procedures
The design of the port should take account of the consequences of abnormal events. These fall into two categories - those that will occur and those that might occur. Among the former, procedures may need to be investigated for a safe unberthing manoeuvre in
deteriorat-ing weather conditions; among the latter, may be the subsequent manoeuvres following main engine or steering mechanism failure. A sound basis for these procedures may be determined through real-time simulation and refined with experience in port operations. 3.8 Training
The investment in modelling the port can finally be used for training the operators of the port. Principally, this will involve the pilots who handle the ships. In developing countries there is a shortage of skilled pilots in par-ticular and staff with limited experience need to be trained quickly with enhanced skills and familiarised with the recommended operating
procedures. The importance of this is even
more significant in ports where only large ships will be handled and competence cannot be developed through experience with smaller tonnage.
4. SPECIFIC APPLICATIONS AND THEIR OUTCOME 4.1 Aids to Navigation
After a century of operating on a daylight basis only, economic pressures were brought to introduce night-time berthing and unberth-ing. The port handled container ships over 200m in length and bulk carriers up to Panamax
size. Although not strongly effected by tides,
the port was very exposed to high winds. In three days' simulation, the Operations Manager, together with the Senior Pilot, deter-mined the optimum manoeuvring procedures for various wind conditions and the location and characteristics of the aids to navigation
required. Four months after the study, the
additional lights were in place and berthing during the hours of darkness was introduced. In the interim, all other pilots were familiar-ised with the planned changes and given the opportunity to refine their shiphandling skills to the new task. Pilots and management had together participated in introducing this sig-nificant development and an improvement in productivity was achieved at little capital cost.
4.2 Fendering
A single berth facility constructed 30 years previously to cater for ships of 16,000 dwt and located in a position exposed to wind and sea had, over the years, accepted ships up
to 26,000 dwt. To keep the facility and the
very considerable shore-side investment com-mercially viable, the facility had to be up-graded to take ships of up to 33,000 dwt. The major considerations included the fendering
of the structure which was based on a platform located on two caissons set 55 metres between the centres and the remoteness of tug
in cases where strong winds could be predicted two days in advance) had been assisted by lines boats of very moderate ship-assist capability. Additional complications, occasioned by the restricted approach angle due to shoal water, will not be discussed here. Consulting engineers were engaged to upgrade the fendering and, as an initial measure, monitored the
berth-ing velocity of ships usberth-ing the facility at
that time. They then designed a fendering
system which would take the berthing loads of the larger ships which would use the berth in
the future. Supported by company management,
the engineer, together with the pilots, sought to use simulation to determine whether these larger ships could be berthed within the design-ed load limitations. Specifically, could the ship be berthed with lines boats assistance so that
the LCG of the ship was within 15m of the midpoint between the caissons
the angle of the ship to the berth at time of first contact did not exceed 15°
longitudinal velocity of the ship at point of contact was minimal
lateral berthing velocity on either fender did not exceed 15 cms/sec?
Initial real-time simulation was conducted using a model of the 26,000 dwt ships which had been using the berth for the previous 15 years, so as to validate the model. Following successful validation, the model of the 33,000 dwt ship was introduced and the abilities of the pilots to berth within these parameters was determined for various limiting environ-mental conditions. The co-operation between, and mutual respect for, the professional integ-rity of management, engineering and nautical staff was a feature of this difficult, but precise, study and essential for the successful outcome.
4.3 Dredging at the Berth
At another proposed marine terminal, real-time simulation supported by calculation, showed that the unberthing of ships in a tideway could only be successfully achieved during peak velocity periods by warping a ship's stern around the berthing dolphin to an angle of 15° so as to point the ship through the tide. This resulted in a review of the dredging pro-gramme in the vicinity of the berths, in order to accommodate the unanticipated angle of the ship to the berth.
4.4 Tug Requirements
A port which had, for some years, berthed loaded Cape-sized bulk carriers with the assistance of four tugs, reviewed the financial viability of its operations and sought to reduce its tug
fleet. Plans were drawn up and processed to
the point of receiving tenders for dredging a new approach channel. Senior management sought confirmation of this new proposal through real-time simulation. The General Manager and Senior Pilot attended the simulator
on which both existing and new channels were
modelled. With some encouragement from the
college staff involved, it was concluded that safe berthing could be achieved using the existing channel and two tugs instead of four. 4.5 Design
An oil company was planning to replace an off-shore discharging facility with an SBM in
deeper water. The area was being simulated
for investigation into other matters related
to the port. Although no prior consideration
had been given to simulating the operations at the SBM, the pilots involved in the other investigation asked for an SBM to be installed in the model so as to evaluate its position in relation to shoal grounds. As a result of this ad hoc study, initiated by themselves, the pilots recommended that the SBM be re-located with a saving of 400m in pipeline length.
A proposal was being developed for the con-struction of a single berth mineral loading facility for Cape-sized bulk carriers. The engineers, after evaluation of surveys, offered three options - each option with significant cost differences. To examine these options, the company hired the simulator for five days and commissioned the simulation of the area
so that each of the three options could be
investigated. The chief executive of the
company, design engineers and marine operations personnel attended the investigation.
Option 1, strongly favoured by management, was a jetty end-on to the trestle with no requirement for transfer towers. Options 2 and 3 placed the jetty at right angles to the trestle, with each option costing consider-ably more than Option 1, but differing in cost due to variations in the piling needs. Each option was carefully evaluated and a unanimous decision was made to recommend to the 'Board of Directors' that Option 3, the more expensive construction, should be built. A report was prepared on the spot, using the records of the simulation runs and the handling of ships at each of the options was video-taped. The report and video tapes were presented at the next Board meeting and the proposal approved without delay.
4.6 Channel Lay-out and Dimensions The management of a small port proposed to make a major investment to develop the port
for a new trade. This involved extensive
dredging and the construction of new berths. Approaches to the new berths would involve turning Panamax-sized bulk carriers in ballast
and backing stern first to the berths.
Operations personnel had expressed concern with the dimensions of the approach channel to the berths on account of the strong winds prevalent at the port and the limitations of the tug assistance available. To fully investigate these concerns, the top management of the port, together with the Harbour Master, Pilot and Tugmaster, attended a real-time simulation investigation of the manoeuvres involved. These showed that provided adequate lead marks were provided, ships could be safely brought to the berths, thus convincing the operations personnel to withdraw their reservations. The personal involvement of senior management assisted in the successful outcome of this investigation.
4.7 Operating Procedures
A port under considerable pressure to increase its export tonnage, sought improved throughput by reviewing operating procedures. With the departure of laden ships being controlled by the height of the tide and with no provision for ships to pass in the approach channel, the delay in placing another ship on the berth was investigated. The practice at that time was to berth Cape-sized and larger bulk car-riers on the flood tide following the departure of the loaded vessel - a delay of some ten to twelve hours. Due to the strength of the tidal stream, berthing of ships on the ebb tide had not been considered. As part of a simulation study involving other aspects of port operations, all pilots were encouraged to investigate the possibility of berthing Cape-sized ships on the ebb tide. During these investigations, the Harbour Master and General Manager personally observed the sim-ulation runs and discussed the problems associated with the operation with the pilots
involved. As a consequence of this, the
operating window was extended to include berth-ing on the ebb tide, with considerable increase in usage of the terminal facilities being achieved without any need for capital invest-ment.
At another port a similar situation existed, but with no possibility of berthing other than on the flood tide. Without extra dredging, it was possible to buoy and mark a by-pass channel which would allow an inbound ship to leave the one-way channel and make an approach to the loading facility shortly after a laden ship had departed, thus enabling a departure and a berthing on the same tide. However, such a procedure required careful scheduling, as the incoming ship had to clear the one-way channel for the departing ship which, once off the berth, was committed. The area and the operation were simulated and a thorough investigation proved the feasibility of the proposal.
4.8 Emergency Procedures
The investigation of any proposal for ship manoeuvring operations in a port area should include evaluation of risks which will occur should malfunction of one form or another OCCUE
It is essential that sufficient margins of safety exist so that when they do occur escape routes, or other means, are available to pre-vent damage to the ship or the facility. To the practising mariner and pilot, these malfunctions will occur at some time during
their careers. Such occurrences include:
engine: failure to start, loss or power
black-out of electrical systems rudder failure
anchor: jamming or windlass failure
instrument failure: radar, sounder, log etc.
tug failure: loss of power or steering,
broken tow-line
crew failure: incorrect helmsman response,
delay in making the tug fast etc.
While it would be unrealistic to include these possibilities in all simulation activities, it is important for the simulator operator and the port operator to take such events into consideration when evaluating a port design or operation.
The designers of an oil terminal envisaged a situation where ships of up to 7,000 dwt would berth at a jetty during any stage of
the tide. In the area, the tidal stream had
a velocity of up to 2 knots. On the ebb tide, the main pipe-carrying trestle lay some 200m downtide of the berth. With senior management of the port, design engineers and operations personnel present, procedures were developed in real-time simulation which enabled berthing and departure in any of the environmental con-ditions prevailing. Account was then taken of the occurrence of any of the malfunctions referred to above. The results showed that while procedures could be developed which reduced the risk should such a malfunction occur, the possibility of the ship drifting onto the main trestle could not be excluded. As the consequences of such an occurrence would be both financially and
environmentally
catas-trophic, the proposed design was abandoned. 4.9 TrainingThe design of a marine facility should take into account the capabilities of the personnel who will operate it. Such capabilities are largely the result of selection, training and
experience. While this applies to most
particularly relevant to the role of the marine
pilot. In many developing nations, it is
dif-ficult to recruit experienced mariners. The opportunities for more lucrative employment elsewhere, do not make such jobs attractive. To fully benefit from the investment in design and construction of a port facility it is necessary to make a further investment in the training of personnel who will play key roles in its operation. It is usual, therefore, to conclude real-time simulation investigations, such as those referred to above, with a pro-gramme of pilot training. Unfortunately, the design of marine terminals is frequently concluded without the involvement of those who will operate them and sometimes with inadequate consideration of the problems involved. In such cases, training may alleviate the conse-quences of unfortunate design.
A jetty-based loading facility was constructed in a relatively exposed location and too in-frequently used and remote to warrant expend-iture on tug assistance for berthing ships.
Initially, the intention was to load 30,000 dwt bulk carriers, but the requirements were soon upgraded to Panamax-sized ships. The jetty was orientated such that the predominant current set across the berth at a velocity approaching 0.5 knots and the most common wind blew across the berth at a velocity of 20 to
25 knots. Shoal water existed at the inward
end of the jetty. During construction, the Authority with responsibility for providing pilotage services sought the assistance of simulation in determining berthing strategies and for the training of personnel who would manoeuvre ships at this port. As no tugs were available to assist ships, any strategy which involved a head-in approach was discarded as involving too high a risk of grounding in the event of a misjudgment. The approach chosen, which has been used successfully for some years, involves skirting the shoals on the landward end of the jetty and using an anchor to check the rate of approach to the
jetty. Inherent in this strategy was the
ability to abort the manoeuvre at any time should the current be stronger than expected or any misjudgment be made. Since the commence-ment of operations, all pilots berthing ships at this facility are trained on the simulator
before handling ships at this facility. This is a need which has been recognised by the facility owner and the pilotage authority.
5. THE CASE FOR CO-OPERATION
It is the frequent comment of those who handle ships that the people who designed the port had little knowledge of the complexities of
shiphandling. From the management side, it
is not infrequently commented that shiphandlers ask for too many tugs or put unnecessary
restrictions on the handling of ships. There is an element of truth in each argument. As the commercial necessity to make the correct decisions from the start and utilise facilities to the maximum becomes more imperative, the pressure on management and operations personnel becomes more intense. This not infrequently leads to tensions and a lack of understanding which is not conducive to sound operations. When planning new facilities, it would seem
essential to involve in the planning process, all parties involved in the venture. In the past, this has been done to some degree. Plans have gone from one office to another for comment, meetings have been held and views
expressed. Eventually, a decision is made
and everyone learns to live with it, whether it is the best decision or not. Where views have been expressed and ignored resentment remains, future co-operation suffers and, if problems have been overlooked, there will be cost disadvantages for a long time to come. The ability to simulate a proposal and to examine the operations of a facility at the design stage enables all parties to understand the intentions and problems of the others. If investigated in this way, each discipline management, engineering or marine operations -sees the total picture in proper perspective. An understanding is achieved by all those
involved as to why certain decisions are made and how various aspects of the project relate
to each other. The benefits of this are not
THE FIRST STEP TO A COMPREHENSIVE PROBABILISTIC DESIGN OF THE HORIZONTAL DIMENSIONS OF INLAND WATERWAYS.
ir. T. Dijkhuis, ir. H.B. Smits.
Rijkswaterstaat; Transportation and Traffic Research Division, P.O. Box 1031, 3000 BA Rotterdam, The Netherlands.
The dimensions of fairways and channels are based on a deterministic
calculation method. This results in horizontal dimensions based on a worst case scenario. From an macro-economic viewpoint this is not the best
solution. The Dutch Ministry of Public Works and Water Management is
investigating the possibilities of a probabilistic method for the design of the Dutch waterways and the admission policy on those waterways.
1. INTRODUCTION.
This paper will indicate a new solution to the problems encountered when
designing the lay-out and dimensions of inland-waterways.
In short the history and the importance to the Dutch economy of the waterways will be discussed. Thereafter the presently used deterministic method will be presented with its
shortcomings. The required improvements and the possible solution of many of the problems is sought in a
probabilistic method, which will be discussed. Finally the developments for the future will be presented.
1.1. History.
The Dutch waterways are of great
importance to both the economy and the safety of Holland.
Almost all Dutch waterways are part of the ground-water management system. Much of the excess water in Holland is transported by its channels and rivers. The waterways are also used for the transportation of people and goods. In this century the transportation of mass goods from the Rotterdam harbour to the German "Ruhrgebiet" has been important for both the development of the
waterways as well as the development of the Dutch economy.
Through the rise of the motorcar and the lorry the number of waterways in use for the transportation of goods has decreased dramatically in this century.
Nevertheless the Dutch inland waterways still very important for the
transportation of mass-goods. Regarding international transportation of goods inland-navigation is more important than road- and rail-transport.
An efficient use of the waterways to maintain this position is consequently very important.
1.1.1. Admission policy.
For the Dutch circumstances the international CEMT (Commission
Europenne des Ministres des Transport) classification based on the hull
dimensions has been slightly adapted by the Dutch commission of
waterway-managers (CVB). See Table 1 for the CVB-classification.
Table I The Dutch vessel classification.
In former years there was no government controlled admission policy for the inland waterways.
The dimensions of the vessels in relation to the dimensions of the restrictions determined the use of a
Class Tonnage [t] Length [In) Beam [In] Draft [m] I 300 39.0 5.1 2.20 II 600 55.0 6.6 2.50 IIa 800 65.0 7.2 2.55 III 1200 80.0 8.2 2.60 IV 1500 85.0 9.5 2.80 V 2500 110.0 11.4 3.50
waterway.
Nowadays the admission policy on the Dutch inland waterways is governed by the classification of the fairway. This classification indicates the maximum class that is allowed on the waterway.
(on a class IV fairway the maximum ship-size is class IV).
The regional waterways-managers implement their own admission policy based on the CVB guidelines and on the specific circumstances of the waterways under their jurisdiction.
Based on this classification the Dutch commission of waterway-managers (CVB) designed rules of thumb for the
definition and lay-out for the different waterway-classes.
1.1.2. Deterministic fairway design
rules.
The rules are based on scientific research and practical knowledge. The mix of both resulting in a practical set of design rules. These rules are widely used in Holland.
The CVB-rules are based on a strip theory in which every vessel requires a certain path-width, sailing-strip, safety strip and a bank-strip, see
Figure 1. For every fairway the river-bank
Figure 1 The different traffic strips.
deciding traffic situation is defined based on the transport- and
consequently vessel-type prognoses. (eg. The meeting of an empty class V vessel and a loaded class IV vessel under windforce 6 conditions). The CVB rules contain guidelines to determine
the critical situation.
For the critical traffic situation the required fairway-width is determined using the strip-theory.
The selection of
the criticalvessel
traffic situation
determines more than
anything else the dimensions.
Due to the deterministic approach of the CVB-rules it is impossible to ascertain the margin of safety of the
fairways. Based on information of skippers and measurements on fairways this margin is thought to be quite
large.
In some other European countries a quite different approach to admission of vessel is used. The skippers
themselves determine what is possible and what is not. The margin of safety is consequently much smaller.
This is the reason for constant
pressure on the waterways-managers to be more lenient in their admission
policy.
1.2. Pressure on the
waterways-managers.
The average size of the ships on the Dutch inland waterways is still
increasing. The equipment on the vessels and consequently the
manoeuvrability improves. Based on this the owners demand a more lenient
admission policy.
With a higher intensity of vessels on the waterway the macro-economic
cost/benefit ratio decreases. This is another factor regarding the pressure on the waterway-managers.
In Holland the so-called class V and under, waterways are most important in this respect.
On the larger waterways the pressure is less. This might be caused by the fact that the economy of size is
counteracted by the demand for high frequency of delivery.
On the river Rhine the demand for admission of large vessels has not
increased over the years. The six-barge pushtows still are the largest vessels and will probably remain so.
Due to logistic problems and the
required minimum waterlevel the number of trips with six-barge pushtows from Rotterdam to Germany is still limited. Holland has several waterways which judged on the dimensions of the restrictions like locks and bridges bank-strip a a < ID sail --s rip
i
path-width safety-strip , sailing-stripC.:3
thank-stripcould admit larger vessels, e.g.: the "Julianakanaal", the "prinses Margriet kanaal" and the "van
Starckenborgkanaal".
The "Julianakanaal" in the south of Holland can accommodate and admit class V vessels although the dimensions of the fairway are approximately according to class III. This situation is judged safe when the number of class V vessels
is small.
This raises question like How safe?
How many class V vessels ?
The traditional deterministic method cannot give the answer. According to the CVB-rules the dimensions of the fairway will have to be increased. The cost of all this will be payed for by the government. For a government which is trying to decrease its costs this poses a problem.
So the pressure on the waterways-managers is two-fold, shortage of finances for waterways improvement and request for more a lenient admission policy.
This started a discussion in the waterways department of the
Transportation an Traffic Research Division with regard to the
possibilities of a different approach to admission policy and fairways design, in order to decrease the required waterway-dimensions and to realise a more lenient admission policy.
2. THE OBJECTIVE OF A NEW METHOD.
A new design method will have to decrease the dimensions required for fairways and/or will have to increase the number and type of ships admissible on the waterway.
The economics of the new method with regard to construction costs,
maintenance costs and benefits of the transportation costs will have to be ascertained. Only when this cost benefit analysis shows a favourable outcome compared to existing practise, the new method will be introduced. This paper will not go into details about the economics of the new design method as this will be of importance only if a practicable new method is available.
2.1. Possible approaches for a new
method.
Several avenues of research have been suggested, the two methods under investigation will be presented:
Firstly, it could be possible to change the admission policy from a method based on the main dimensions of the vessels to a method based on the manoeuvring characteristics. The
absolute restrictions due to locks and bridges remain, the restrictions of size on a stretch of waterway will disappear in favour of the more logical aspects of the ships capacity to
manoeuvre.
Secondly, it could be possible to
design the fairway dimensions according to a probabilistic approach, as used for example in many engineering designs and in the waterdepth design and the admission policy of the channels to all Dutch seaports.
The first method is under investigation as an admission policy on the river Rhine and its confluents. The
preliminary results are very promising. The method will be presented at a later
date.
It is hoped that a probabilistic approach will decrease the design dimensions, increase the admission of
ships and show the 'safety margin of the waterway.
3. PROBABILISTIC DESIGN METHODS.
Probabilistic methods are used in most areas of engineering.
The main difference from traditional design methods is that instead of a
worst case approach, with or without a
safety factor, the probability of all factors in the lifetime of the design are taken into account. Thus
representing a copy of the possible lifetime load-history of the design. A problem with the method is that the probability of all design-factors has to be known. In most cases this is not
possible.
Another difference from traditional design methods is that most
probabilistic design methods are in fact risk-analyses. Apart from the probability of all design-factors the consequences of failure of the design
are taken into account using the following definition:
Risk = Probability * Consequences. The degree in which the different failure modes of the design are taken into account determines if the analysis is called a risk-assessment or a
probabilistic design.
3.1. Probabilistic methods for marine applications.
In many engineering problems the
stochastic components of the conditions influencing the design can be
represented more or less by a normal Gaussian process. This enables a comprehensive statistical calculation. Where navigating vessel are concerned this is not possible. For example, the distance form the bank of a river will highly influence the behaviour of the helmsman, consequently the process is
far from Gaussian, see Figure 2. The
only
comprehensive probabilistic methodin
the nautical environment concerns the design of approachchannels to seaports. This method will
0.024 0.022
0.020
-0.018 -0.016 0.014 -0.012 -0.010 -0.008 -0.006 -0.004 -0 -0-02 -o scenario A scenario 20 40 60 80 100 120 140 160 180 required width [s]Figure 2., The distribution function of the required width for two scenario's.
be presented to indicate the type of approach in maritime probabilistic designs.
3.2. Probabilistic design of the vertical dimensions of channels.
All approach channels to the Dutch seaports are designed according to the same probabilistic method which was developed for the "Euro-Maasgeul", the approach channel to Rotterdam.
This method is called
semi-probabilistic because some inherently deterministic elements are included. For example, only three different motion-response functions are used. The advantage of the method is the explicit way in which the safety
criteria are used as will be discussed in Section 3.2.1.
Another advantage is the possibility to determine the sensitivity of the
calculation for the input-parameters, see Section 3.2.2. This enables an optimization of the classification of the input-parameters.
3.2.1. Safety criteria.
Channel design for the Dutch seaports is based on three criteria.
1. During 25 years of channel use the probability of bottom-contact may not exceed 10%.
Probability of bottom-contact shall not exceed 1% for an individual sailing.
When sailing in calm water the distance between the channel-floor and the hull may not be less than
1 meter.
The first criterion indicates the risk (probability of bottom contact) that is accepted during the lifetime of the channel. This criterion is the only true probabilistic criterion of the
three.
As the Dutch government implements the method based on a daily admission for each individual ship it is not
desirable to admit vessels under extreme
conditions.
Under theseconditions
the probability ofbottom-contact could well be 100%. So the deliberate admission of vessels under dangerous conditions, however small their probability, is excluded by the second criterion.
The last criterion is necessary to
maintain enough
manoeuvrability underThe main conclusion is that when a deliberate admission policy is used the extremes will have to be
precluded
from the calculations.Safety criteria as used in the channel design have been compared to the
criteria as used in the Dutch
Deltaworks, protecting Holland from flooding by the North Sea. The main difference is that the criteria of the Delta works do not take into account the consequences of a certain accident. Only the probability of the accident is taken into account.
The same method has been applied to the channel design although some research into the effect of the hull hitting the channel-floor has been done. It was calculated that a penetration of some 45 cm into a sandy seafloor would not significantly damage the hull. The consequences of a larger collision have not been taken into account.
When investigating the safety criteria the sensitivity of the results to the
criteria can be an important indicator as to the criticality of the design.
3.2.2. Sensitivity analysis.
When using a comprehensive
probabilistic method it is necessary to determine the influence of each design-parameter on the required
fairway-width.
This means that for all parameters the frequency of occurrence will have to be known. See Figure 3., for an example. Using classification of parameters the number of data to be handled is
decreased.
Potentially the quality of the calculation decreases. By using a sensitivity analysis and an optimal choice of the classes the loss of
quality can be limited. An example of a
sensitivity analysis for a
probabilistic calculation can be seen in Figure 4., which shows a calculation of the sensitivity of the percentage of
the tides at which ships cannot be admitted to the draught of the ships and the accuracy of this draught. The results of a comprehensive
sensitivity analysis will enable the designer to optimize the calculations.
3.2.3. Correlation.
In all probabilistic cálculations the interdependence of design parameters
0.) '0 w 0 30 u (3.20 -u u o . i 0 a.) required width [m] 0 1 2 3 4 E 6 7 8 9 10
Wind
[Beauf ort]
Figure 3 An example of the distribution function of the pathwith for different wind-forces. 1U 80
01
50 o 60 40 o W mn
, 10 0 0 0.2 0.4 0.6 0.8Inaccuracy in draught [m]
M ¡co 90-
n-I 14 70 -4 80 -.4-) 80 40 n -2o -o 12 14 16Draught [m]
Figure 4 The sensitivity of the
admittance percentage per tide for the shipdraught and the accuracy of the shipdraught.
causes a problem. The calculations are infinitely more complex when the
correlation of the parameters are
unknown. When investigating nautical problems the correlation of parameters poses a real problem. For example the path-width is dependent of the wave-height which is dependent of both current and windforce. The path-width is also dependent of the shiptype, of
10
the traffic situation which is dependent of the ship, of the
windforce, of the manoeuvrability of the vessel, of the capabilities of the skipper, of the waves etc.
Assessment of all relevant correlations is not feasible so a "deterministic" approach of the correlations will have to be made. In the proposed method almost all inter-dependencies have been neglected as can be seen from Chapter 4. A method to correct the results will be presented also.
4. PROBABILISTIC METHOD FOR THE HORIZONTAL DIMENSIONS OF A WATERWAY.
As was illustrated in the last Chapter a probabilistic design method requires intimate knowledge of all factors concerned.
As in all probabilistic designs the safety criteria are of great importance for the design of the horizontal
dimensions of a fairway or channel, Section 4.1.
The method to imitate the use of safety factors in the new method is discussed in Section 4.2.
A large difference between engineering problems in which probabilistic
techniques are used and the design of fairways is the complexity of the interaction between the ships on a waterway. This is one of the main reasons why the proposed method is based on the simulation of traffic, Section 4.3., rather than on the traditional method of classifying all determining factors and performing a comprehensive risk-analysis.
The required fairway dimensions follow from the traffic simulations and are discussed in Section 4.4.
As with all new design methods for Dutch waterways there are International implications which are indicated in Section 4.5.
4.1. Safety criteria.
Two different ways to design a set of safety criteria are possible.
First of all; a comparison with existing criteria, including the criteria for the vertical channel design, can be used.
Secondly; a comparison with accident rates on existing fairways can be implemented.
A problem with the latter approach is that the number of accidents will be
related to the difficulty of sailing on the fairway, le. the traffic intensity, the fairway-lay-out, the cross-section of the fairway, the wind and waves etc. Moreover there will have to be a
differentiation between accidents caused by mechanical problems and accidents caused by the infrastructure. The first results of preliminary
research show that de definition of safety criteria will be extremely difficult.
As the problems with defining these criteria cannot be solved within the time schedule of the project a
different solution has been proposed. The possibility of verification of the
fairway-width calculated with the probabilistic method by comparing it with an existing fairway.
4.2. Comparison with existing fairways.
The comparison with existing fairways is advantageous with respect to not having to define safety criteria. The disadvantage of the method is that the inherent safety factor of an existing fairway will be duplicated, and still the safety-margin is not shown.
Consequently the choice of the reference fairway is of great
importance. A fairway with a just-safe and fluent traffic has to be selected. The comparison will be implemented as
follows:
The differences between the required
width
from practise and the results ofthe calculations with the new
method
are used as a correction-factor. This factor will consequently be used
for all design purposes.
The description of traffic is very important in the design of a fairway, traffic simulation is used for this.
4.3. Traffic simulation.
The proposed method is based on traffic simulation in which the probability of occurrence of different situations corresponds with the reality on a fairway. In this sense the method is probabilistic. See Figure 5., for an
example of traffic simulation.
The traffic simulation will have to be able to indicate:
* The frequency of occurrence of the
different traffic situations and the required fairway-width.
IL
Ii
03===
=I)
111:1111
Figure 5., An example of the proposed traffic simulation.
* The consequences of
traffic-regulations on the required fairway-width. (eg. prohibition of
overtaking for certain ships under specific wind conditions)
* The influence of
equipment-requirements for the whole (or part of) the fleet.
The Waterways Department has at its disposal a traffic simulation model SIMDAS. This model simulates traffic on a fairway based on a complex set of helmsman-decision rules. The result is a realistic image of the traffic on a fairway. The main disadvantage of this model for the proposed method is the fact that the decision rules never allow a ship to run ashore. So, the results cannot be used for a
probabilistic design of the required fairway-width. The effect of a wider or narrower fairway on the average sailing time, can be calculated using SIMDAS, but only for a qualitative comparison. But because of the relatively low vessel traffic intensity on almost all Dutch inland-waterways the results are
not very discriminating and of little use in designing waterways.
Consequently a new method with simpler decision rules and an infinite fairway-width will be implemented.
4.3.1. General description of the
method.
On a fairway of infinite width vessels are generated at both ends of the fairway. The distribution of
ship-types, the intensities, speed-distribution and the required path-width (depending on windforce and shipspeed) are taken into account. Along the fairway, (a cross-section somewhere halfway) the traffic
situation and all parameters like path-width, speed , wind, etc. are recorded.
The distribution-function of the required waterwidth is determined. A combined distribution-function for all traffic-situations will be the final result of the simulation.
The total required fairway-width, for an unhindered navigation, is the smallest width at which the frequency of occurrence is O.
This calculation contains traffic situations which have an excessive width requirement and an extremely low
frequency of occurrence (eg. the overtaking of two empty vessels under windforce 6 conditions). These traffic situations will be avoided in practice or will be forbidden by the
waterways-manager.
Consequently, the traffic simulation will have to be corrected for these extreme situations. A kind of traffic-regulation will be incorporated in the model. It is expected that one or several iterations will be required to obtain a realistic
traffic-representation.
From the resulting width-distribution-function it is possible to determine the required fairway-width based on an accepted frequency of exceedence. See Figure 6. In a round-about way safety criteria are introduced. The accepted frequency of exceedence is comparable
0.013 0.012 -0.011 -0.010 -0.009 -0.008 -0.007 -0.006 -0 -0-05 -0.004 -0.003 0.002 0.001 -o 1% 20 40 60 80 100 120 140 160 180 required width [m]
Figure 6. An example of the width
distribution function and the use of an exceedance criterion.
to a probabilistic safety criterion. The traffic regulations are the safety criteria necessary because of the implementation of a deliberate admission policy.
The calculation method contains many inaccuracies. The assumed individual path-width distribution combined with the traffic-modelling are expected to cause the largest error.
As it is extremely time consuming and complex, the individual errors in the premises are not looked into. The total result of the calculation will be
verified by comparison with a real life situation, according to the method of Chapter 4.2.
4.3.2. A closer look at some aspects of the method.
The vessels are simulated according to a ship-type distribution. Given a specific ship, random selection of speed and path-width is employed.. The path-width is valid for single vessel traffic. This width will be influenced by the type of traffic
situation encountered. During a meeting of ships the path-width of both vessel will be decreased.
Moreover, the resulting path-width will moreover also be influenced by the behaviour of the helmsman. This effect will only be incorporated in a next generation of the method.
Because the simulation will be based on a fairway of infinite width, extreme traffic situations are considered
possible, eg. the interaction of six or more vessels. See Figure 5. In reality, this will not occur due to the width restrictions of the fairway. In practice, the vessels will decide on executing overtaking manoeuvres depending on the available fairway-width. While in reality "traffic-jams" will occur, the simplified traffic simulation will not show this
phenomenon. To simulate the behaviour of the skipper, the traffic simulation can use traffic regulation to exclude the extremes of the traffic-situations.
From all external conditions only the wind is taken into account at this stage of the investigation. The wind is represented by a fixed speed and
direction for each simulation. To represent the real wind-conditions this process is repeated for all speed and direction combinations. The frequency of occurrence of each combination is taken into account. For these
simulations the traffic-regulations remain constant. The complete set of calculations for the wind with constant traffic-regulations will be called
scenario.
The simulation of a scenario will be stopped after sufficient convergence of the results. The results of the traffic simulations for each scenario can be summarized as follows:
* A frequency distribution of the traffic situations and the distribution of the required fairway-width. Also all other parameters are available eg. external circumstances, speed, shiptype and equipment, degree of loading, path-width of individual vessels etc.
* Number of times that a traffic regulation was in effect and the type of traffic regulation.
The effect of current and waves will as yet not be taken into account. In a later stadium this can easily be
implemented. The sane holds true for a curved fairway-section.
4.4. Required fairway dimensions.
The aforementioned method only takes account of probabilities and not of the risks. To increase the understanding of the influence of high risk vessels it is possible to investigate the effect of a larger required path-width for vessels with dangerous goods. In this way the "safety-margin" for these
vessels is increased. The effect on the required fairway-width is an indication of the sensitivity of the waterway-width to the number of vessels with dangerous goods.
Using the proposed method of traffic simulation it is not possible to determine the safety-level of the fairway. By comparing the required fairway-width with an existing fairway it is possible to indicate qualitative
effects.
4.5. International implications.
Holland has many waterways that are
shared with other countries. When a new design method for admission policy on
the Dutch waterways is implemented the method will eventually have to be discussed on an international level.
This will be more important as Unified Europe takes shape.
For inland waterways the government can easily implement a new admission policy which is more lenient.
FUTURE DEVELOPMENTS.
Although it is early days to indicate future developments for a method which will have to prove itself yet, some possible improvements are:
The use of a Comprehensive traffic simulation model like the SIMDAS will be considered. The advantage of this type of model is the degree of reality of the ship-behaviour. The proposed method does not take into account all factors relevant to the design-process. A next step could be a complete probability analysis. In this analysis all
design-factors will be considered on
a probabilistic level.
FINAL REMARKS.
The first steps towards a new design method for (inland) waterways will be taken in 1992.
The method looks quite promising. It is expected that before mid 1993 the
method will be tested and available for practical application.
ACKNOWLEDGEMENTS.
We would like to thank our colleagues for their constructive criticism. We also like to thank the working group for class V inland waterways of the
Theun ELZINGA
Frederic R. Harris B.V., Consulting Engineers, Badhuisweg 11, 2587 CA The Hague, The Netherlands
The Maritime Simulation Centre Netherlands (MSCN) launched this year their new simulators and facilities to participate in simulation races regularly held in the maritime world.
This paper presents the home-port-concept to illustrate required skills and to
demonstrate some requirements and challenges for manoeuvring simulator operators, like MSCN, to sail a competitive and successful course.
1. 1992: A FUTURE HISTORICAL YEAR?
The year 1992 is already a commemorable maritime year in many ways:
In 1492 Columbus, in search for an
alternative route around the West to the Indies, discovered "by accident" the Americas after an adventurous trip over the Atlantic Ocean.
In 1932 the forerunner of the present
Maritime Research Institute Netherlands (MARIN), the Netherlands Ship Model Basin
(NSMB), was opened in Wageningen to
explore new research facilities for ship design.
In 1972 the Dutch surprised the maritime world with the first real-time ship manoeuvring simulators: unique tools for port design and training of maritime personnel.
In 1992 the Maritime Simulation Centre Netherlands (MSCN) presents their new visuals and capabilities to the outside world.
The opportunities for the MSCN to make indeed 1992 the next maritime historical year, look promising from these perspective views, but what are the real challenges to sail a successful course and how can treacherous cliffs be avoided in maritime "simulation land"?
May I, as a representative of consulting
engineers, present some views in this
respect?
CHALLENGES FOR A COMPETITIVE MSCN
2. FREDERIC R. HARRIS CONSULTING ENGINEERS
When Admiral Frederic R. Harris started the company in 1927 (yes, were are just a bit older than our host MARIN), he laid the foundation for an international consultancy
firm. Nowadays Frederic R. Harris is a
multi-disciplinary firm of international
consultants providing comprehensive
professional services not only for port and harbours but also for transportation, energy, military facilities, land development, water resources and environmental.
In port planning and engineering Harris' capabilities and past experience are
comprehensive covering all cargo
transportation modes and encompasses all facilities required from the point that vessels enter the port approaches to the hinterland interface.
Over the years, Harris has undertaken
assignments in some 100 countries world wide for the successful development of projects on behalf of national and regional government departments and agencies, industrial and commercial organisations and international funding agencies.
