Pub Date : 2023-02-07DOI: 10.5750/ijme.v164ia3.1242
H. M. Wang, X. Y. Chen, H. M. Yu, L. Chen, T. Wang, J. R. Xu, X. Wang
Due to the effect of water depth, hydrodynamic characteristics of ships manoeuvring in shallow waters are quite different from those in deep water. In the present study, the CFD method is used to investigate the hydrodynamic behaviour of the ESSO OSAKA model in model-fixed condition in deep and shallow waters by solving RANS equations, which performs steady turning motion with the effect of free surface considered. The governing equations are discretized by the finite volume method (FVM) and the free surface is captured by applying the volume of fluid (VOF) method. Viscous hydrodynamic characteristics and flow fields in a series of cases at different water depths and speeds are investigated respectively. By comparing the numerical results in shallow water with those in deep water, it was found that effects of water depth and free surface are significant on ship’s hydrodynamic forces. The coefficients of drag, lateral force and yaw moment all increase with the decrease of water depth. The drag coefficient in shallow water is about 45% larger than that in deep water. However, effect of water depth on the lateral force coefficient is small, it is about 15% larger in shallow water than that in deep water. While, it has significant effect on the yaw moment coefficient, which is about 25% larger in shallow water than in deep water. And as the water depth increases, the effect of the free surface gradually becomes smaller. Both coefficient of pressure component of drag force and drag coefficient in the present simulation are about 7% smaller than the case without considering the free surface at h/d ≥ 3.0, while that of frictional component is almost the same. When h/d ≥ 3.0, the lateral force and yaw moment coefficients are almost the same as when the free surface is not considered. The error between the present numerical result and the measurements is within 10%, which indicates that RANS method has promising capability to predict the hydrodynamic forces on ships manoeuvring in shallow water.
{"title":"NUMERICAL SIMULATION OF THE VISCOUS FLOW AROUND SHIPS TURNING IN SHALLOW WATER","authors":"H. M. Wang, X. Y. Chen, H. M. Yu, L. Chen, T. Wang, J. R. Xu, X. Wang","doi":"10.5750/ijme.v164ia3.1242","DOIUrl":"https://doi.org/10.5750/ijme.v164ia3.1242","url":null,"abstract":"Due to the effect of water depth, hydrodynamic characteristics of ships manoeuvring in shallow waters are quite different from those in deep water. In the present study, the CFD method is used to investigate the hydrodynamic behaviour of the ESSO OSAKA model in model-fixed condition in deep and shallow waters by solving RANS equations, which performs steady turning motion with the effect of free surface considered. The governing equations are discretized by the finite volume method (FVM) and the free surface is captured by applying the volume of fluid (VOF) method. Viscous hydrodynamic characteristics and flow fields in a series of cases at different water depths and speeds are investigated respectively. By comparing the numerical results in shallow water with those in deep water, it was found that effects of water depth and free surface are significant on ship’s hydrodynamic forces. The coefficients of drag, lateral force and yaw moment all increase with the decrease of water depth. The drag coefficient in shallow water is about 45% larger than that in deep water. However, effect of water depth on the lateral force coefficient is small, it is about 15% larger in shallow water than that in deep water. While, it has significant effect on the yaw moment coefficient, which is about 25% larger in shallow water than in deep water. And as the water depth increases, the effect of the free surface gradually becomes smaller. Both coefficient of pressure component of drag force and drag coefficient in the present simulation are about 7% smaller than the case without considering the free surface at h/d ≥ 3.0, while that of frictional component is almost the same. When h/d ≥ 3.0, the lateral force and yaw moment coefficients are almost the same as when the free surface is not considered. The error between the present numerical result and the measurements is within 10%, which indicates that RANS method has promising capability to predict the hydrodynamic forces on ships manoeuvring in shallow water.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2023-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46239592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-07DOI: 10.5750/ijme.v164ia3.784
A. Kılıç, Utku Cem Karabulut, Emrah Akdamar, L. Bilgili
In this study, NOx emissions from diesel engines of 75 recreational boats were measured on-board in accordance with the simplified method specified in the NOx Technical Code. The study was carried out in boats with ranging between 14.42 m-37.50 m in length and engines power varying between 138 kW–2,040 kW. NOx emissions were measured by using a portable exhaust gas analyser (Testo 350 Marine) in ppm in a dry basis. An in-house program was developed to calculate the final emission results in g/kWh. The main aim of the study is to develop NOx emission factors for recreational boats, which are not specifically included in previous emission factor studies. The NOx emissions of the marine diesel engines of the recreational boats were found in range of 0.92 g/kWh – 10.69 g/kWh while the mean emission factor was found as 4.81 g/kWh.
{"title":"DETERMINATION OF NOX EMISSION FACTOR FOR DIESEL ENGINES OF RECREATIONAL BOATS BY ON-BOARD MEASUREMENT","authors":"A. Kılıç, Utku Cem Karabulut, Emrah Akdamar, L. Bilgili","doi":"10.5750/ijme.v164ia3.784","DOIUrl":"https://doi.org/10.5750/ijme.v164ia3.784","url":null,"abstract":"In this study, NOx emissions from diesel engines of 75 recreational boats were measured on-board in accordance with the simplified method specified in the NOx Technical Code. The study was carried out in boats with ranging between 14.42 m-37.50 m in length and engines power varying between 138 kW–2,040 kW. NOx emissions were measured by using a portable exhaust gas analyser (Testo 350 Marine) in ppm in a dry basis. An in-house program was developed to calculate the final emission results in g/kWh. The main aim of the study is to develop NOx emission factors for recreational boats, which are not specifically included in previous emission factor studies. The NOx emissions of the marine diesel engines of the recreational boats were found in range of 0.92 g/kWh – 10.69 g/kWh while the mean emission factor was found as 4.81 g/kWh.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2023-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42373575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-07DOI: 10.5750/ijme.v164ia3.1164
Mia Elg, Timo Korvola, B. Molchanov, Lien Tran, J. Lappalainen
Alternatives for enhancing a cruise ship’s energy efficiency were investigated by introducing different waste heat recovery technologies and battery systems in the machinery. A ship designer’s in-house ship energy system simulator was applied in a cloud-based framework for simulation-based optimization. This multi-objective optimization with economic and environmental objectives used genetic algorithm for finding the best overall solution in a complex ship energy system design task. The results suggest that adding battery capacity alone contributes very moderately to reducing the case ship fuel consumption and, therefore, carbon emissions. Nevertheless, a combination of steam turbines and organic Rankine cycle units would offer the largest fuel saving potential with the lowest investment cost in the case setup. Also, the main engines’ running hours were of interest. The presented approach can bring significant added value for sustainable ship design with minimal additional effort.
{"title":"Improving ship sustainability by re-using engineering simulators in multi-objective optimization","authors":"Mia Elg, Timo Korvola, B. Molchanov, Lien Tran, J. Lappalainen","doi":"10.5750/ijme.v164ia3.1164","DOIUrl":"https://doi.org/10.5750/ijme.v164ia3.1164","url":null,"abstract":"Alternatives for enhancing a cruise ship’s energy efficiency were investigated by introducing different waste heat recovery technologies and battery systems in the machinery. A ship designer’s in-house ship energy system simulator was applied in a cloud-based framework for simulation-based optimization. This multi-objective optimization with economic and environmental objectives used genetic algorithm for finding the best overall solution in a complex ship energy system design task. The results suggest that adding battery capacity alone contributes very moderately to reducing the case ship fuel consumption and, therefore, carbon emissions. Nevertheless, a combination of steam turbines and organic Rankine cycle units would offer the largest fuel saving potential with the lowest investment cost in the case setup. Also, the main engines’ running hours were of interest. The presented approach can bring significant added value for sustainable ship design with minimal additional effort.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2023-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43785678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-07DOI: 10.5750/ijme.v164ia3.809
M. Tadros, M. Ventura, C. Guedes Soares
In this paper, a propeller optimization model is presented to find the optimum propeller geometry and the gearbox ratio for different angles of the propeller shaft while minimizing the amount of fuel consumed at a given speed and complying with the proposed constraints' limitations. The developed model couples several simulation software where application programming interface (API) facilitates data processing to achieve the optimum design based on optimization procedures. A fishing vessel is selected as a case study to perform the numerical simulation. A comparison study is conducted between the optimized propellers at different inclination angles of the propeller shaft among different propeller blades. Bar chart and box and whisker plot are the two techniques considered to visualize the computed data. The results conclude that the optimized propeller with a high number of blades and a small inclination angle (2 degrees) can operate at the engine operating point as in a horizontal propeller shaft, which is considered the most efficient from the theoretical point of view.
{"title":"AN OPTIMISATION PROCEDURE FOR PROPELLER SELECTION FOR DIFFERENT SHAFT INCLINATIONS","authors":"M. Tadros, M. Ventura, C. Guedes Soares","doi":"10.5750/ijme.v164ia3.809","DOIUrl":"https://doi.org/10.5750/ijme.v164ia3.809","url":null,"abstract":"In this paper, a propeller optimization model is presented to find the optimum propeller geometry and the gearbox ratio for different angles of the propeller shaft while minimizing the amount of fuel consumed at a given speed and complying with the proposed constraints' limitations. The developed model couples several simulation software where application programming interface (API) facilitates data processing to achieve the optimum design based on optimization procedures. A fishing vessel is selected as a case study to perform the numerical simulation. A comparison study is conducted between the optimized propellers at different inclination angles of the propeller shaft among different propeller blades. Bar chart and box and whisker plot are the two techniques considered to visualize the computed data. The results conclude that the optimized propeller with a high number of blades and a small inclination angle (2 degrees) can operate at the engine operating point as in a horizontal propeller shaft, which is considered the most efficient from the theoretical point of view.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2023-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46975378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-07DOI: 10.5750/ijme.v164ia3.725
Birgül Arslanoğlu, Gizem Elidolu, Tayfun Uyanık
Purpose - This study aims to predict seafarer safety perceptions and evaluate their feedbacks in order to understand the human factor on ship’s safety. Design/methodology/approach - A questionnaire survey has been conducted with 304 seafarers' participation and they responded several safety climate and perception indicators that based on literature, for instance safety assessment of supervisors and company, company's training arrangement, accident and near miss reporting etc. Scores of survey results have been estimated with four machine learning algorithms, namely as multiple linear regression, support vector regression, random forest and decision tree regression. Findings - The multiple linear regression method gave the best prediction performance for seafarer safety perception level with 4.07 mean absolute percentage error. Originality - It was seen that the machine learning techniques can be applicable in the prediction of seafarer safety perception based on collected data. This study may provide useful perspectives for maritime companies in the improving safety on ships.
{"title":"APPLICATION OF MACHINE LEARNING METHODS FOR PREDICTION OF SEAFARER SAFETY PERCEPTION","authors":"Birgül Arslanoğlu, Gizem Elidolu, Tayfun Uyanık","doi":"10.5750/ijme.v164ia3.725","DOIUrl":"https://doi.org/10.5750/ijme.v164ia3.725","url":null,"abstract":"Purpose - This study aims to predict seafarer safety perceptions and evaluate their feedbacks in order to understand the human factor on ship’s safety. \u0000Design/methodology/approach - A questionnaire survey has been conducted with 304 seafarers' participation and they responded several safety climate and perception indicators that based on literature, for instance safety assessment of supervisors and company, company's training arrangement, accident and near miss reporting etc. Scores of survey results have been estimated with four machine learning algorithms, namely as multiple linear regression, support vector regression, random forest and decision tree regression. \u0000Findings - The multiple linear regression method gave the best prediction performance for seafarer safety perception level with 4.07 mean absolute percentage error. \u0000Originality - It was seen that the machine learning techniques can be applicable in the prediction of seafarer safety perception based on collected data. This study may provide useful perspectives for maritime companies in the improving safety on ships.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2023-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42543467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-07DOI: 10.5750/ijme.v164ia3.1153
Wei Zhou, Cheng Fang
As a main force of ocean shipping, the energy consumption of container ships is considerably high due to the frequent load shifts of main engine and other disturbances. In this study, for engine room power systems in intelligent container ships, including cooling water subsystems, fuel oil subsystems, and main engine subsystems, a coordinated control scheme based on a correlation model and a distributed model predictive control approach was proposed to reduce continual fluctuations of control and output values through optimisation in a negotiated manner. The correlation model considers the interconnections among the subsystems, and the control approach achieves Nash equilibrium solutions. A comparative simulation was carried out between the proposed method and the decentralized model predictive control. The result shows that the proposed method works better than the decentralized one with less fluctuations. This study provides a theoretical basis for integrated designs of power control systems in intelligent container ships.
{"title":"Distributed Scheme for Main Engine Power Control Systems of Small and Medium Sized Container Ships Based on Nash Equilibrium","authors":"Wei Zhou, Cheng Fang","doi":"10.5750/ijme.v164ia3.1153","DOIUrl":"https://doi.org/10.5750/ijme.v164ia3.1153","url":null,"abstract":"As a main force of ocean shipping, the energy consumption of container ships is considerably high due to the frequent load shifts of main engine and other disturbances. In this study, for engine room power systems in intelligent container ships, including cooling water subsystems, fuel oil subsystems, and main engine subsystems, a coordinated control scheme based on a correlation model and a distributed model predictive control approach was proposed to reduce continual fluctuations of control and output values through optimisation in a negotiated manner. The correlation model considers the interconnections among the subsystems, and the control approach achieves Nash equilibrium solutions. A comparative simulation was carried out between the proposed method and the decentralized model predictive control. The result shows that the proposed method works better than the decentralized one with less fluctuations. This study provides a theoretical basis for integrated designs of power control systems in intelligent container ships.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2023-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45433409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-07DOI: 10.5750/ijme.v164ia3.793
Kyoung-Woo Lee, Gil-Yong Han, Jang-Won Seo, Jae-hyuk Choi, Manneung Kim
In this study, the bilge pumping performance was investigated using the actual bilge pumping arrangement of a 180K class bulk carrier, and it was assumed that the No. 1 cargo hold was fully flooded. As a result of the calculation, the mean water velocity at bilge main could not satisfy the 2m/s requirement while discharging all the accumulated water from the flooded No. 1 cargo hold with the actual arrangement installed on the 180K class bulk carrier. As a result of the calculation by modified arrangement, it was found that the 2 m/s requirement could be satisfied when a pipe smaller than the required internal diameter according to the rule requirements of classification societies was applied to the bilge main under the same pump conditions. In addition, it was found that the flow rate of the pump should be increased by at least 40% when piping acceptable for the rule requirements of classification societies was applied to the bilge main. The bilge pumping system of 180K bulk carriers may be similar for every ship, and in our opinion, urgent modifications and repair are necessary for consideration of the characteristics of bulk carriers with a relatively high risk of flooding. According to the GBS structure, the rule requirements of classification societies regarding bilge pumping system should comply with the intended purpose of SOLAS Regulation II-1/35-1. It is proposed to revise SOLAS Regulation II-1/35-1 by applying the concept of Performance-Based Standard (PBS) in order to secure the performance of the bilge pumping system by applying a pipe smaller than the required internal diameter according to the rule requirement of classification societies. In particular, it is proposed that SOALS Regulation II-1/35-1.3.9, the requirement for the required internal diameter of bilge main, should be deleted so that any size pipe can be used if the bilge pumping performance can satisfy the 2 m/s requirement. Finally, “2 m/s Criterion” is proposed only design criteria to fulfill the intended purpose of the 2 m/s requirement of SOLAS.
{"title":"PROPOSED DESIGN CRITERIA FOR A BILGE PUMPING SYSTEM: A CASE STUDY OF LARGE BULK CARRIER","authors":"Kyoung-Woo Lee, Gil-Yong Han, Jang-Won Seo, Jae-hyuk Choi, Manneung Kim","doi":"10.5750/ijme.v164ia3.793","DOIUrl":"https://doi.org/10.5750/ijme.v164ia3.793","url":null,"abstract":"In this study, the bilge pumping performance was investigated using the actual bilge pumping arrangement of a 180K class bulk carrier, and it was assumed that the No. 1 cargo hold was fully flooded. As a result of the calculation, the mean water velocity at bilge main could not satisfy the 2m/s requirement while discharging all the accumulated water from the flooded No. 1 cargo hold with the actual arrangement installed on the 180K class bulk carrier. As a result of the calculation by modified arrangement, it was found that the 2 m/s requirement could be satisfied when a pipe smaller than the required internal diameter according to the rule requirements of classification societies was applied to the bilge main under the same pump conditions. In addition, it was found that the flow rate of the pump should be increased by at least 40% when piping acceptable for the rule requirements of classification societies was applied to the bilge main. The bilge pumping system of 180K bulk carriers may be similar for every ship, and in our opinion, urgent modifications and repair are necessary for consideration of the characteristics of bulk carriers with a relatively high risk of flooding. According to the GBS structure, the rule requirements of classification societies regarding bilge pumping system should comply with the intended purpose of SOLAS Regulation II-1/35-1. It is proposed to revise SOLAS Regulation II-1/35-1 by applying the concept of Performance-Based Standard (PBS) in order to secure the performance of the bilge pumping system by applying a pipe smaller than the required internal diameter according to the rule requirement of classification societies. In particular, it is proposed that SOALS Regulation II-1/35-1.3.9, the requirement for the required internal diameter of bilge main, should be deleted so that any size pipe can be used if the bilge pumping performance can satisfy the 2 m/s requirement. Finally, “2 m/s Criterion” is proposed only design criteria to fulfill the intended purpose of the 2 m/s requirement of SOLAS.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2023-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48498930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-28DOI: 10.5750/ijme.v164ia2.1175
Casper van Lynden, I. van Winsen, C. Westland, A. Kana
To reach the sustainable targets and to reduce the investment risk, there is a need for more certainty and predictability regarding the requirements of the future offshore wind installation vessels. To capture the fast changing offshore wind market and its impact on vessel requirements, this paper generates scenarios using Epoch-era analysis. A parametric model is created to determine the performance of a set of vessels defined by their length, beam, depth, crane capacity, speed, and transport strategy in the different scenarios. The strength of combining Epoch-era analysis and parametric modelling is that the performance criteria and input variables can be tailor-made to a stakeholders strategy resulting in robust input variables for the concept vessel design.
{"title":"Offshore Wind Installation Vessels","authors":"Casper van Lynden, I. van Winsen, C. Westland, A. Kana","doi":"10.5750/ijme.v164ia2.1175","DOIUrl":"https://doi.org/10.5750/ijme.v164ia2.1175","url":null,"abstract":"To reach the sustainable targets and to reduce the investment risk, there is a need for more certainty and predictability regarding the requirements of the future offshore wind installation vessels. To capture the fast changing offshore wind market and its impact on vessel requirements, this paper generates scenarios using Epoch-era analysis. A parametric model is created to determine the performance of a set of vessels defined by their length, beam, depth, crane capacity, speed, and transport strategy in the different scenarios. The strength of combining Epoch-era analysis and parametric modelling is that the performance criteria and input variables can be tailor-made to a stakeholders strategy resulting in robust input variables for the concept vessel design.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43107120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-28DOI: 10.5750/ijme.v164ia2.1170
Dr P Loscombe
The Nordic longships of the 9th to 11th Centuries were perhaps the preeminent fast assault ships of the period. Modern engineering analytical tools have been employed from time to time to investigate their stability, performance and structural characteristics. The latter is perhaps the most challenging, since the physical problem is that of a hydro-elastic body in rough seas, constructed of a material with highly variable mechanical properties, fastened together by rivets, treenails, nails, spikes, lashings and wedges of uncertain joint efficiency. The corresponding analysis is potentially considerably more complex than the ‘linked-chain’ method commonly employed in modern design offices to establish acceptable scantlings, i.e. classification society rule loads and criteria together with reliable published material property data which are the essential inputs to scantling formulae/finite element analyses (FEA). This paper outlines one small craft naval architect’s view of the issues involved in applying the standard structural design method to the analysis of a ship type which is radically different from modern craft and in so doing identify issues which may be of interest to modern naval architects analysing unconventional lightweight structures.
{"title":"Analysing Ancient (Viking) Longship Structures","authors":"Dr P Loscombe","doi":"10.5750/ijme.v164ia2.1170","DOIUrl":"https://doi.org/10.5750/ijme.v164ia2.1170","url":null,"abstract":"The Nordic longships of the 9th to 11th Centuries were perhaps the preeminent fast assault ships of the period. Modern engineering analytical tools have been employed from time to time to investigate their stability, performance and structural characteristics. The latter is perhaps the most challenging, since the physical problem is that of a hydro-elastic body in rough seas, constructed of a material with highly variable mechanical properties, fastened together by rivets, treenails, nails, spikes, lashings and wedges of uncertain joint efficiency. The corresponding analysis is potentially considerably more complex than the ‘linked-chain’ method commonly employed in modern design offices to establish acceptable scantlings, i.e. classification society rule loads and criteria together with reliable published material property data which are the essential inputs to scantling formulae/finite element analyses (FEA). This paper outlines one small craft naval architect’s view of the issues involved in applying the standard structural design method to the analysis of a ship type which is radically different from modern craft and in so doing identify issues which may be of interest to modern naval architects analysing unconventional lightweight structures.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46228338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-28DOI: 10.5750/ijme.v164ia2.1231
OC Astrup, O. Aae, T. Kus, O. Uyanik, B. Biterling, T. Bars, M. Polini, V. G, K. Yu, T. Seppälä, M. Son
Shipyards and classification societies must modify the traditional design documentation and review process and enable a direct 3D digital classification process to improve the exchange of information between the different stakeholders and ultimately accelerate the classification process. The Open Class 3D Exchange (OCX) standard represents a step-change in this context. The OCX is a vessel-specific standard addressing the information needs of the classification society and is a key enabler to replace traditional 2D class drawings with a 3D model. The successful and seamless exchange of the design models exported from 4 independent 3D CAD systems to the classification society’s rule calculation tool has been demonstrated. The application of the OCX models for the prescriptive rule calculations demonstrates that the OCX model can carry all the information required by the classification society’s Rules for this purpose. The possibility to also display the detailed features of the design model in a neutral web-based viewer provides the necessary capability for full visual verification of the design models.
{"title":"Moving Towards Model Based Approval – The Open Class 3D Exchange (OCX) Standard","authors":"OC Astrup, O. Aae, T. Kus, O. Uyanik, B. Biterling, T. Bars, M. Polini, V. G, K. Yu, T. Seppälä, M. Son","doi":"10.5750/ijme.v164ia2.1231","DOIUrl":"https://doi.org/10.5750/ijme.v164ia2.1231","url":null,"abstract":"Shipyards and classification societies must modify the traditional design documentation and review process and enable a direct 3D digital classification process to improve the exchange of information between the different stakeholders and ultimately accelerate the classification process. The Open Class 3D Exchange (OCX) standard represents a step-change in this context. The OCX is a vessel-specific standard addressing the information needs of the classification society and is a key enabler to replace traditional 2D class drawings with a 3D model. The successful and seamless exchange of the design models exported from 4 independent 3D CAD systems to the classification society’s rule calculation tool has been demonstrated. The application of the OCX models for the prescriptive rule calculations demonstrates that the OCX model can carry all the information required by the classification society’s Rules for this purpose. The possibility to also display the detailed features of the design model in a neutral web-based viewer provides the necessary capability for full visual verification of the design models.","PeriodicalId":50313,"journal":{"name":"International Journal of Maritime Engineering","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42142070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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