A review of existing knowledge regarding how to manage ice during offshore work in cold waters has been carried out. The objective has been to contribute to increased safety and efficiency in future projects by learning from world-wide experiences. It was found that offshore drilling has been carried out in a wide range of ice conditions and at water depths spanning from five metres to more than a thousand metres. Icebergs in open waters have been handled safely over several years and the possibility of detecting icebergs is considered good. With respect to icebergs frozen in sea ice, both detection and deflection is considered difficult and the technology for doing so is not proven. Good ice management systems are considered to represent the main factors for operating successfully in the covered waters. Future work should focus on how to include the effect of ice management statistically in a design process.

With the widespread use of mobile devices and increased demand for mobile services, Location-Based Services (LBS) represent a promising addition to service offerings of network operators as well as third-party service providers. Based on long-term research in LBS, our group has proposed a generic Enhanced LBS Reference Model (ELRM), which describes the concept, the architecture and the functionalities of the LBS. In addition, an evolutionary information process has been identified within the LBS, that represents knowledge maturity from position awareness to situation awareness. Both the ELRM and the information evolution process in LBS are presented in this article and illustrated by a case study within the framework of the 3GPP-standardised IP Multimedia Subsystem (IMS). This case-study emphasises the opportunities for navigation- and LBS-related solutions development provided by modern telecommunication technologies.

The modernisation of GPS and the introduction of Galileo will introduce the use of Binary Offset Carrier (BOC) modulation. BOC will be implemented as either a sine or cosine sub-carrier modulation, which affects the spectral properties of the signal and the receiver search, acquisition and tracking processes. This paper addresses the effect of the various forms of BOC modulation on the receiver search process. Theory is developed to draw comparisons between search techniques and verified with computer simulation models.

In recent months the US and the EU have agreed to change the modulation scheme for the new civil GPS and Galileo signals in the L1 band from Binary Offset Carrier (1,1) (BOC(1,1)) to a scheme having the so-called Multiplexed Binary Offset Carrier (MBOC) spectrum, although each system will implement this differently. This paper compares the performance of the new system in a number of areas against the original baseline. It is shown that the MBOC signal offers significant advantages in multipath and tracking performance, while retaining compatibility with BOC(1,1) receivers at the cost of a small correlation loss.

Many ingenious mechanical methods were used by hydrographic surveyors for measuring the depth of water in the early part of the 20th Century. These were superseded by echo-sounding and sonar techniques in the later decades. Relatively few of the mechanical methods were used by merchant ships but, in the years before radar and satellite navigation, they, and the increasingly popular echo sounder, had a useful place in the navigator's armoury of navigation aids. This paper is not intended to provide a detailed description of the development of sounding devices. Sections 1 to 5 simply outline the principles of the sounding devices with which the authors were familiar during their time at sea. In Sections 6 to 9 the authors recount their anecdotal experiences of the way in which they, personally, used depth measuring devices during the middle years of the 20th century.

Integrated electronic marine systems are becoming part of the numerous screens which are to be found on ships' bridges and in wheelhouses of fishing vessels. This paper continues previous work which has focussed on perceived safety aspects of integrated electronic marine systems, in particular, a small study completed within the last two years which showed that some fishing skippers had negative perceptions of integrated electronic marine systems. This present study uses semi-structured interviews with skippers in the United Kingdom fishing fleet to show that integrated electronic marine systems can be perceived as increasing safety as well as being of good value in terms of need and cost. It is possible that such perceptions are dependent on experiencing the use of integrated electronic marine systems within off-shore trawling.

The Automatic Identification System (AIS) is an efficient tool to exchange positioning data among participating naval units and land control centres. It was developed primarily as an advanced tool for assistance to sailors during navigation and for the safety of the life at sea. Maritime security has become a major concern for all coastal nations, especially after September 11, 2001. The fundamental requirement is maritime domain awareness via identification, tracking and monitoring of vessels within their waters and this is exactly what an AIS could bring. This paper will be focused on how the AIS-derived information could be used for coastal security, maritime traffic management, vessel tracking and monitoring with the help of GIS technology. The AIS data used in this paper was collected by the Canadian national aerial surveillance program.

The roll motion of a ship on waves is one of the six degrees of freedom and is the most difficult to predict since it deals with a motion similar to a spring-mass damper system, poorly damped by ship generated waves, in addition to the action of waves from the high seas. This problem increased from the second half of the 19th century when sailing propulsion was replaced by steam machines and iron replaced wood, which led to design modifications in ships affecting transversal stability, with the result of an increment in the ship's roll motion. As a consequence, it has been necessary to develop different systems which, on the one hand, increase the natural period of this motion in order to decrease its amplitude and reduce the risks that the wave encounter frequency would resonate with the natural frequency of the ship's motion; and on the other hand, to generate a damping effect to this motion. Bilge keels, passive stabilisers with no moving parts, form the simplest and cheapest element that may be incorporated on a ship to reduce this motion. This paper studies roll motion in general and then analyses bilge keels from different points of view.

With conventional snapshot RAIM algorithms, it is difficult to detect small errors and simultaneous multiple faults. Assuming that we know the system dynamics, filtering algorithms, such as the Kalman filter, can provide better integrity-monitoring performance than the snapshot algorithms because the filter reduces the noise level of measurements. However, because the Kalman filter presumes that measurement noise and disturbance follow the Gaussian distribution, its performance might degrade if the assumption is wrong. To address this problem, we propose a fault detection and exclusion algorithm using Gaussian sum filters. Because GNSS measurement noise does not follow the Gaussian distribution perfectly, the Gaussian sum filter can estimate the posterior distribution more accurately; therefore it has better integrity-monitoring performance. This paper describes the detailed algorithms and shows simulation results to evaluate the integrity-monitoring performance of the algorithms. The proposed algorithms detect about 30% smaller faults and generate 35% lower protection levels than the conventional methods. The results show that the proposed algorithms can provide better accuracy and availability performance.

The Kalman filter (KF) is a form of optimal estimator characterized by recursive evaluation, which has been widely applied to the navigation sensor fusion. Utilizing the KF requires that all the plant dynamics and noise processes are completely known, and the noise process is zero mean white noise. If the theoretical behaviour of the filter and its actual behaviour do not agree, divergence problems tend to occur. The adaptive algorithm has been one of the approaches to prevent divergence problems in the Kalman filter when precise knowledge on the system models is not available. Two popular types of adaptive Kalman filter are the innovation-based adaptive estimation (IAE) approach and the adaptive fading Kalman filter (AFKF) approach. In this paper, an approach involving the concept of the two methods is presented. The proposed method is a synergy of the IAE and AFKF approaches. The ratio of the actual innovation covariance based on the sampled sequence to the theoretical innovation covariance will be employed for dynamically tuning two filter parameters – fading factors and measurement noise scaling factors. The method has the merits of good computational efficiency and numerical stability. The matrices in the KF loop are able to remain positive definitive. Navigation sensor fusion using the proposed scheme will be demonstrated. Performance of the proposed scheme on the loosely coupled GPS/INS navigation applications will be discussed.

The air pollution caused by the use of heavy fuel oil in shipping is a growing problem that is drawing increased attention. Methods have been developed to reduce air emissions from ships, more or less aimed at the choice of fuel and the related air emissions. However, the emissions of particulates, sulphur and carbon dioxide, which contribute to the greenhouse effect are not only related to the choice of fuel but also to the amount of fuel consumed in the combustion engines. This paper proposes an additional method that can contribute to the reduction of the air pollution from ships by decreasing the fuel consumption. This is done by specifying the amount of fuel that can be consumed on a specific ocean crossing and by computing a minimal-time route for that given amount of fuel, so decreasing the fuel consumption in a verifiable way.

Professor Kemp1 has revisited the circumstances in which the Princess Alice crossed ahead of, and was run down by, the oncoming Bywell Castle in 1878. This note focuses on the seamanship of the manoeuvre made by the Bywell Castle in the agony of the moment before collision. This manoeuvre was judged to be wrong at the time. The note concludes by considering how this manoeuvre would be judged today in the light of the seamanship required by Rule 17 of Colregs 1972 and draws attention to proposals made by Captain Phillip Colomb to the Thames Traffic Committee in 1879.