Fouling release coatings (FRCs) can become damaged and diminished over exposure. Quantifying adverse effect of scratches on FRCs is crucial for damage control. This study investigated the effect of four pre-defined scratches on the re-fouling of a silicone-based FRC (SiFR) undergoing underwater cleaning utilizing a novel automated underwater cleaning system (AUCS). Moreover, barnacle adhesion and coating detachment formation of scratched SiFR were evaluated. Field testing at the CoaST Maritime Test Centre (CMTC) demonstrated that the scratches varying in depths and widths can significantly affect the biofouling behavior and cleaning efficiency of SiFR surface. For wide scratches (i.e. 3-mm-wide), hard fouling (e.g. barnacles, mussels) was more prone to accumulate, and underwater cleaning was effective in preventing hard fouling but not soft fouling on SiFR surface. Additionally, the re-fouling and cleaning difficulty of hard fouling increased with the depth of wide scratches. For narrow scratches (i.e. <50-μm-wide), SiFR was primarily attached by soft fouling (e.g. biofilm, algae), and underwater cleaning performed positive fouling resistance of algae but not biofilm on SiFR surface. Besides, algae became difficult to remove with the depth of narrow scratches. Notably, biweekly cleaning proved to be highly effective in biofouling control of SiFR with narrow and shallow scratches.
Operational cycles for maritime transportation is a new concept to improve the assessment of ships’ energy efficiency and offer benchmarking options among similar ship types and sizes. This work extends previous research to consolidate the methodology, bring more comprehensiveness, and provide a more holistic assessment of these operational cycles. The cycles are designed from noon reports from a fleet of around 300 container ships divided into eight size groups. The comparison between cycles derived from speed and draft with those based on main engine power identifies that the cycles based on speed and draft are more accurate and allow for estimating the Energy Efficiency Operational Index but require more data. The main-engine-power cycles are more effective in benchmarking through the Annual Efficiency Ratio. These cycles reduce the inherent variability of the carbon intensity indicator and present good opportunities as a benchmarking tool for strengthening the regulatory framework of international shipping.
Satellite imagery has become a fundamental part for maritime monitoring and safety. Correctly estimating a ship's identity is a vital tool. We present a method based on facial recognition for identifying ships in satellite images. A large ship dataset is constructed from Sentinel-2 multispectral images and annotated by matching to the Automatic Identification System. Our dataset contains 7.000 unique ships, for which a total of 16.000 images are acquired. The method uses a convolutional neural network to extract a feature vector from the ship images and embed it on a hypersphere. Distances between ships can then be calculated via the embedding vectors. The network is trained using a triplet loss function, such that minimum distances are achieved for identical ships and maximum distances to different ships. Comparing a ship image to a reference set of ship images yields a set of distances. Ranking the distances provides a list of the most similar ships. The method correctly identifies a ship on average 60 % of the time as the first in the list. Larger ships are easier to identify than small ships, where the image resolution is a limitation.
The cold ironing system is gaining interest as a promising approach to reduce emissions from ship transportation at ports, enabling further reductions with clean energy sources coordination. While cold ironing has predominantly been applied to long-staying vessels like cruise ships and containers, feasibility studies for short-berthing ships such as ferries are limited. However, the growing demand for short-distance logistics and passenger transfers highlights the need to tackle emissions issues from ferry transportation. Incorporating electrification technology together with integrated energy management systems can significantly reduce emissions from ferry operations. Accordingly, this paper proposes a cooperative cold ironing system integrated with clean energy sources for ferry terminals. A two-stage energy management strategy combining sizing and scheduling optimization is employed to reduce the port's emissions while minimizing system and operational costs. The proposed system configuration, determined through the sizing method, yields the lowest net present cost of $9.04 M. The applied energy management strategy managed to reduce operational costs by up to 63.402 %, while significantly decreasing emissions from both shipside and shoreside operations. From the shipside, emissions reductions of 38.44 % for CO2, 97.7 % for NOX, 96.69 % for SO2, and 92.1 % for PM were achieved. From the shoreside, the approach led to a 28 % reduction across all emission types. Thus, implementing cold ironing powered by clean energy sources is a viable solution for reducing emissions generated by ferry operations. The proposed energy management approach enables emissions reduction and delivering cost-effectiveness at ferry terminals.
Sensing data from vessel operations are of great importance in reflecting operational performance and facilitating proper decision-making. In this paper, statistical analyses of vessel operational data are first conducted to compare manual noon reports and autolog data from sensors. Then, new indicators to identify data aberrations are proposed, which are the errors between the reported values from operational data and the expected values of different parameters based on baseline models and relevant sailing conditions. A method to detect aberrations based on the new indicators in terms of the reported power is then investigated, as there are two independent measured power values. In this method, a sliding window that moves forward along time is implemented, and the coefficient of variation (CV) is calculated for comparison. Case studies are carried out to detect aberrations in autolog and noon data from a commercial vessel using the new indicator. An analysis to explore the source of the deviation is also conducted, aiming to find the most reliable value in operations. The method is shown to be effective for practical use in detecting aberrations, having been initially tested on both autolog and noon report from four different commercial vessels in 14 vessel years. Approximately one triggered period per vessel per year with a conclusive deviation source is diagnosed by the proposed method. The investigation of this research will facilitate a better evaluation of operational performance, which is beneficial to both the vessel operators and crew.
The effectiveness of fouling release coatings (FRCs) may diminish over time in the seawater. Underwater cleaning of FRCs in service is crucial for biofouling control. This study investigated the effects of cleaning parameters (brush moving speed, cleaning force and frequency) on a silicone-based FRC (SiFR) aged for 2 months (A2-SiFR) and 13 months (A13-SiFR), simulating the short-term and long-term FRCs in service. Fouling resistance, re-fouling and cleaning efficiency utilizing a self-designed automated underwater cleaning system (AUCS) were examined. Moreover, coating surface characterization, including visual appearance condition, roughness, water contact angle were evaluated on the testing surfaces. Field testing at the CoaST Maritime Test Centre (CMTC) demonstrated that underwater cleaning exhibited positive effect on the long-term fouling control performance of aged FRCs. Besides, stronger cleaning force, slower moving speed and biweekly cleaning led to better fouling resistance. No significant damages were observed on A2-SiFR surface, while regular spiral and circular scratches appeared on A13-SiFR surface. The damages led to adverse effects on fouling resistance, re-fouling and cleaning efficiency of algae on the cleaned A13-SiFR surface, affecting the coating performance more than cleaning parameters. Despite these damages, the cleaned surfaces still exhibited a higher fouling resistance compared with the ones without cleaning.
Antifouling properties of unmodified kraft lignin for potential use in marine coatings were investigated. The study was based on preliminary findings that pointed toward lignin’s efficacy against seawater organisms during laboratory tests. Coatings were formulated that contained lignin as a filler and had a pigment volume concentration above the critical pigment volume concentration. This ensured direct interaction between lignin and seawater organisms, as the lignin particles remained incompletely wetted by the binder. Moreover, all formulations were waterborne to mitigate the release of volatile organic compounds. Despite the initial promise, the antifouling performance of the formulated lignin coatings during field experiments at the CoaST Maritime Test Center was limited, and the anticipated mechanism must be reconsidered. Additionally, it was found that high lignin concentrations, while facilitating organism interaction, compromised the coating's mechanical properties. Nevertheless, the waterborne coating formulation introduced here might provide a foundation for other researchers to further investigate lignin’s potential as a bio-based pigment or a filler in coatings.
Accurate and reliable optical remote sensing image-based small-ship detection is crucial for maritime surveillance systems, but existing methods often struggle with balancing detection performance and computational complexity. In this paper, we propose a novel lightweight framework called HSI-ShipDetectionNet that is based on high-order spatial interactions and is suitable for deployment on resource-limited platforms, such as satellites and unmanned aerial vehicles. HSI-ShipDetectionNet includes a prediction branch specifically for tiny ships and a lightweight hybrid attention block for reduced complexity. Additionally, the use of a high-order spatial interactions module improves advanced feature understanding and modeling ability. Our model is evaluated using the public Kaggle and FAIR1M marine ship detection datasets and compared with multiple state-of-the-art models including small object detection models, lightweight detection models, and ship detection models. The results show that HSI-ShipDetectionNet outperforms the other models in terms of detection performance while being lightweight and suitable for deployment on resource-limited platforms.
GreenHopper is the first Danish zero-emission ferry developed as a test platform for autonomous waterborne navigation technologies. The paper presents technology development within the innovation project ShippingLab Autonomy, which led to the commissioning of GreenHopper at Limfjorden (DK) in December 2022. The technology research resulted in a holistic system architecture for surface vessel autonomy, based on distribution of functionality and responsibility on software modules, similar to the structure observed in the International Maritime Organization (IMO) Seafarers Training Certification and Watch-keeping (STCW) regulatory framework. The paper shows how this approach results in an architecture that supports safe behaviours of individual modules and of autonomous navigation at a system level. The paper presents the individual modules, specific features and benefits. Elements of the regulatory framework are highlighted to poise technology approval by maritime authorities. The paper reflects on lessons learned, discusses continued technology validation in dedicated operational scenarios.
The accelerated melting of the Arctic ice leads to the navigation of the Northern Sea Route (NSR) linking Asia and Europe, shortening transport channel between China and the European Union (EU). This has a significant impact on the China-EU bilateral trade which is analyzed in the present study. We present a framework based on a general equilibrium model for analyzing the impact of the NSR on the trade and the economies of China and the EU. Different fuel cost scenarios, consisting of fuel prices and sailing speeds on ice, are also considered. Specifically, we measure the changes in shipping costs between China and the EU, brought about by NSR navigation. These are used as a basis to quantify changes in transport technology. The Global Trade Analysis Project (GTAP) model is used to predict the trade and economic impacts. The results show that the NSR can save 0.98% in shipping costs and generate an increase in the exports of China and the EU in the order of 14,986 and 8,228 million US dollars, respectively. Among these exports, the mining industry shows the fastest growth, while the electronics industry experiences the largest increase in trade volume. Our findings reveal the potential of the NSR as an alternative route and its positive impact on bilateral trade between China and the EU. The results can provide a basis for shipping companies and governments to make decisions regarding the use of Arctic routes.