Shared pilot passage plan and navigational safety during pilotage

Navigating in confined waters with a pilot aboard requires that the pilot’s intention and plan is understood by all present on the bridge. The present study investigates the effect of having a detailed route plan and monitoring it in the context of pilotage. The aim was to see how the presence of a shared pilot passage plan in the Electronic Chart Display and Information System (ECDIS) affects the identification and recovery from navigational errors made by a pilot. Twenty participants, 10 with a shared route plan and 10 without, participated as navigators in a simulator scenario involving pilotage in the Oslofjord. Participants were bachelor students in nautical science. The navigation scenarios involved the intentional error by the pilot just before a predefined way point. Three measurements of relevance to navigational safety were recorded: (1) the time it took the participant to express concern, (2) the time it took the participant to correct the error (‘time to recovery’), and (3) the number of groundings. The study revealed that time to express concern and time to recovery were significantly much shorter for the group with a shared pilot passage plan presented in ECDIS than for the group without such a plan. Providing a bridge team with a shared pilot passage plan in ECDIS during pilotage might improve the ability to identify and correct navigational errors.     

Culture in maritime safety

Many accidents, resulting in a larger number of fatalities during the last few years, have focused attention on issues of maritime safety. Accident registration reveals that a large proportion have human related causes, and indicates that, by looking at cultural aspects, one's understanding of the underlying mechanisms leading to accidents might increase. Several constructs of culture and climate have appeared on national, organizational and safety levels. Those constructs are discussed together with problems that occur when interpreting accidental data, and recording accidental causes. The papers reviewed indicate the existence of a ‘chain of evidence’ from accidents/safety to attitudes, communications, conflict-solving, etc. and further to safety culture. To be able to reduce the risk for accidents, there seems to be a need for coordination and the cultural perspective seems to be one that integrates and takes the many disciplines and multi-level nature of accidents and safety into account.     

Mooring line tension observed through a maximum entropy spectrum

A method for measuring mooring line tension is proposed based on observation of the natural frequencies of the mooring line segment between the winch and the fairlead. The anchor line tension is observed through the string equation where an analytical expression for the line's eigen-frequencies is obtained. The tension is observed on line by utilizing a nonparametric system identification approach in which the peaks of a maximum entropy spectrum of the transverse acceleration measures of the vibrating string are automatically identified. The method is verified against full-scale data from the Troll B floating concrete oil production platform operating in the North Sea. Received for publication on Feb. 24, 1999; accepted on July 26, 1999     

Participating mass in colliding risers

One of the main challenges in estimating impact energy in collisions between marine risers is the assessment of the riser mass involved in the collision. Evidently the entire riser mass does not contribute to the collision. Hence, the question is: What is the equivalent riser mass which contributes to the impact energy? This article presents three different ways of estimating the riser mass participating in the collision energy. The first method is strictly experimental. The second method uses a numerical experiment together with system identification techniques. The third method is a strictly analytical method, which results in an asymptotically upper bounded estimate of the participating mass. Two risers are examined as case studies. The first riser is a 1 : 100 model scale riser used in collision experiments carried out at Marintek's towing tank in Trondheim, Norway. The second case uses a real world riser in use on the Troll B oil production platform operating in the North Sea. The proposed methods yield consistent and comparable results. Received for publication on Feb. 1, 1999; accepted on July 8, 1999     

Culture in maritime safety

Many accidents, resulting in a larger number of fatalities during the last few years, have focused attention on issues of maritime safety. Accident registration reveals that a large proportion have human related causes, and indicates that, by looking at cultural aspects, one's understanding of the underlying mechanisms leading to accidents might increase. Several constructs of culture and climate have appeared on national, organizational and safety levels. Those constructs are discussed together with problems that occur when interpreting accidental data, and recording accidental causes. The papers reviewed indicate the existence of a 'chain of evidence' from accidents/safety to attitudes, communications, conflict-solving, etc. and further to safety culture. To be able to reduce the risk for accidents, there seems to be a need for coordination and the cultural perspective seems to be one that integrates and takes the many disciplines and multi-level nature of accidents and safety into account.     

A meta-analysis of DEA and SFA studies of the technical efficiency of seaports: A comparison of fixed and random-effects regression models

This paper presents a meta-analysis of variations in seaports’ Mean Technical Efficiency (MTE) scores based on 40 studies published in refereed academic journals. We link the variation in estimated MTE scores to differences in the following factors: the frontier methodology used, which essentially are the Data Envelopment Analysis (DEA) and the Stochastic Frontier Analysis (SFA); regions where seaports are situated; type of data used; number of observations; and the total number of variables used. Furthermore, we compare fixed-effects against a random-effects regression model where the latter assumes that the individual study specific characteristics matter while the former assumes that there is one general tendency across all studies. We present several findings based on the data: (1) the random-effects model outperforms the fixed effects model in explaining the variations in MTEs, (2) recently published studies have lower MTE scores as compared with earlier published studies, (3) studies that used nonparametric DEA models depict higher MTE scores as compared with those that used SFA models, (4) panel data studies have lower TE scores as compared with cross-sectional data, and (5) studies using European seaport data produce lower MTE scores when compared with the rest of the world. Finally, our results contradict some previous meta-analysis studies of TE scores. We encourage the use of random-effects models in meta-analysis studies because they account for individual study specific effects.     

Smaller ports’ evolution towards catalysing sustainable hinterland development

ABSTRACT

From simple organizations as gateways for goods and passengers, ports have evolved and transformed into complex organizational systems with multiple functions. Besides providing cargo, logistics, and other kinds of services to its customers, modern ports engage in the development of their hinterlands. Sustainability, evolving from environmental actions over the years, has become the core of many modern ports’ approach towards hinterland development and port competitiveness. While the literature is concerned with and presents examples of large ports implementing sustainability initiatives, the literature is scarce on smaller ports. This article addresses this gap by exploring qualitatively the case of the Port of Aalborg, a medium-sized port in Denmark, and its evolution towards using sustainability for port and hinterland development. The research focuses on the actions behind environmental development at the port. Its evolution is mapped and explored using the analytical framework developed based on the (larger) ports’ development and their roles. The findings from the Port of Aalborg case exemplify how smaller ports can evolve to drive the sustainable development of their hinterlands and contribute to a better understanding of this kind of port.     

Transverse strength analysis of catamarans

Stresses and deformations relevant for transverse strength analysis are calculated for a 60 m catamaran by a compartment model and are compared with corresponding results from a global model. It is found that the flexibility of the partial bulkheads typical for a twin-hull Ro/Ro-vessel is so large that the interaction with the surrounding structure has to be accounted for. If springs are applied, the results are sensitive to the spring stiffness. A web frame model that does not include any bulkheads, gives large errors and is not recommended.     

深海技术：在位稳定性

在海底构筑物的设计中，主要考虑因素之一是构筑物的在位稳定性。构筑物的浸没重量是否足以防止因周围海水涌动造成的倾覆甚至移动？     

Weaving marine food webs from end to end under global change

Marine food web dynamics are determined by interactions within and between species and between species and their environment. Global change directly affects abiotic conditions and living organisms, impinging on all trophic levels in food webs. Different groups of marine researchers traditionally study different aspects of these changes. However, over medium to long time scales perturbations affecting food webs need to be considered across the full range from nutrients to top predators. Studies of end-to-end marine food webs not only span organism sizes and trophic levels, but should also help align multidisciplinary research to common goals and perspectives. Topics are described that bridge disciplinary gaps and are needed to develop new understanding of the reciprocal impacts of global change on marine food webs and ocean biogeochemistry. These include (1) the effects of nutrients on biomass and production, (2) the effects of varying element ratios on food web structure and food quality, (3) bulk flows of energy and material in food webs and their efficiencies of transfer, (4) the ecological effects of species richness and the roles of microbial organisms, (5) the role of feeding behaviour in food web dynamics and trophic controls, (6) the spatial dynamics of communities and links between different food webs, (7) the combined effects of body size and behaviour in determining dynamics of food webs, and (8) the extent to which the ability of marine organisms (and communities) to adapt will influence food web dynamics. An overriding issue that influences all topics concerns the time and space scales of ecosystem variability. Threads link different nodes of information among various topics, emphasizing the importance of tackling food web studies with a variety of modelling approaches and through a combination of field and experimental studies with a strong comparative approach.