• Proceedings of KOSOMES biannual meeting
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• 2017.04a
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• pp.39-39
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• 2017

• International Journal of Ocean System Engineering
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• v.1 no.4
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• pp.211-221
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• 2011

Tugboats are widely used near harbors to assist with various operations such as the berthing and deberthing of very large vessels and the towing of barges. Capsizing accidents involving tugboats occasionally take place when the tugboat makes rapid turns in harsh weather conditions. When there is little evidence suggesting how the accident occurred and when the crew members are missing, it is necessary to predict the time history of the towing vessel’s attitude and trajectory from its departure point to when and where it capsized, depending on various input parameters using a numerical simulation. In this paper, the dynamics of a tugboat and a towed barge in conjunction with the external force and moment were established, and the possible input parameters and operational scenarios which might influence the large roll motion of the tugboat were identified. As a result of analyzing the simulated time history of the excessive roll motion of the tugboat, it was found that roll motion can take place when the tugboat is situated on the crest of a wave and when it is pulled by a towed barge through a towing line. The main cause of the accident would be the parameters that primarily influence such situations. These are the wave parameters, course changing scenario, and the amount of tension.

• Proceedings of KOSOMES biannual meeting
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• 2007.05a
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• pp.101-108
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• 2007

Tugboat has carried out the important role and service in the maritime industry construction, such as port and sea bridge construction, fairway dredging and sea reclamation etc. Furthermore, tugboat takes the largest portion in number of vessel at the domestic registry and barges as big as the general merchant vessel, which are getting specialized and larger, are in operation. In spite of the increase of marine accident under this situation, there has been no proper measure for the safe navigation of tugboat in the aspect of a nation. This paper aims to propose the measure for the safe navigation of tugboat according to the frequent marine accident of tugboat with sea bridge. Therefore, we show a example of the sailing schedule and operation checklist based on the analysis of statistics and precedent of marine accident and the investigation of the actual operation state of tugboat in the aspect of a contract of carriage and a personnel setup, which should be checked by the operator of tugboat, pass through sea bridge safely and propose the safe traffic supporting system based on electronic chart system to improve the safe navigation of tugboat.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.1
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• pp.107-113
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• 2010

The criteria of tugboat requirement in domestic trading ports have been determined by the administrator of regional maritime affairs and port office on the basis of the regulations for the tugboat operations and management. But, there is a little confusion that the criteria of tugboat requirement and method for calculation of them are different from port to port and total power calculated on the basis of power per tugboat requirements by the number of tugs is not in accordance with total required power for the use of tug in several ports. The comparison of tugboat requirements among domestic major ports showed that it should be necessary for the criteria to be made in unified form. Because the current criteria are only on the basis q the ordinary condition with wind velocity under 10m/s, the criteria on the condition of the wind velocity over 10m/s are suggested to be necessary for the precautions against a disaster such as unexpected strong winds or typhoon.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.5
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• pp.445-453
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• 2020

The use of tugboats for the safe berthing/unberthing of ships is the most crucial factor in the safe and efficient operation of the harbor. However, the adequate number and size of tugboats that should be held based on the characteristics of the port have not been investigated in detail, which causes disputes between involved parties. Therefore, the suitable number of tugboats and the ratio of the tugboat horsepower were determined in this study using simulation techniques, with focus on Ulsan Port. First, the ship and tugboat-operating models were designed for simulation application. Next, the input variables defined in the model design were standardized in an inputtable form using ARENA software. In addition, the arrival and division process of the ship was designed and simulated as an ARENA model. Finally, the simulation results for six scenarios showed that an effective tugboat operation could be achieved when 42 tugboats were held at Ulsan Port.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.4
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• pp.71-78
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• 2007

Towing vessels have carried out the important role and service in the maritime industry construction, such as port and sea bridge construction, fairway dredging and sea reclamation etc. Furthermore, tugboat takes the largest portion in number of vessel at the domestic registry and barges as big as the general merchant vessel, which are getting specialized and larger, are in operation. In spite of the increase of marine accidents under this situation, there has been no proper measure for the safe navigation of tugboat in the aspect of a nation. This paper aims to propose the measure for the safe navigation of tugboat according to the frequent marine accident of tugboat with sea bridge. Therefore, we show an example of the sailing schedule and operation checklist based on the analysis of statistics and precedent of marine accident and the investigation of the actual operation state of tugboat in the aspect of a contract of carriage and a personnel setup, which should be checked by the operator of tugboat, to pass through sea bridge safely and propose the safe traffic supporting system based on electronic chart system to improve the safe navigation of tugboat.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.6
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• pp.597-603
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• 2012

It is necessary to accurately evaluate the resistance performance and estimate the towing power of a tugboat for safety towing operation at actual seas. In this study, we have carried out the model tests firstly to investigate the resistance performance and flow characteristics around the tugboat in still water. The experiments are performed in infinite depth in circulation tank using 1/33.75 scaled model from 5kts to 10kts(designed speed 7kts) considering the effect of adverse and favorable current. Then the numerical calculations are executed to analyze the response amplitude operator and added resistance on tugboat due to the waves. The results obtained by the present computation are compared with the those acquired from the experiments in still water. As a result, it is noted that the added resistance become larger at head sea and higher speed conditions. We can also observe that the EHP increase 70 percent in comparison with those in still water.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.4
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• pp.405-411
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• 2014

It needed the calculation of the required tugboat's power to move the damaged vessel to the safe area for reducing the additional damages. In this paper, it was verified the theoretical calculation method on the required power of tugboat through the 93m real ship tests. From the experiments, it was considered that the theoretical calculation method was sufficient to estimate the required power of tugboat. The resistance of the locked propeller was relatively big portions compared with other static resistances such as air resistance, frictional resistance and residual resistance. And dynamic resistance induced by swing movement and yawing was continuously occurred and it also was great effects on the total resistance. In the future, the safety factor will be considered and the exact prediction of ship's resistance will enhance the efficiency of tugboat because of the minimization of safety factor.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.216-219
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• 2021

In the Eco-Friendly Ship Act, the shaft generator is an equipment for eco-friendly ships. However, in order to apply the new technology in ships, high reliability is required, and the HILS (hardware in loop system) test is used as a verification method for this. Therefore, in this paper, a shaft generator is modeled and simulated for HILS test of a tugboat to which a shaft generator is applied. Through simulation, it was verified that the charging/discharging of the shaft generator operates according to the scenario.

• Journal of Ocean Engineering and Technology
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• v.34 no.5
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• pp.285-293
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• 2020

This study evaluated the Hook-up installation of an offshore site construction process, which is the final step in an offshore site installation process. During Hook-up installation, the offshore structure can have a detrimental effect on the work stability due to low-frequency motion. Moreover, economic costs can be incurred by the increase in available days of a tugboat. Therefore, this study developed a numerical analysis program to assess the dynamic behavior of mooring systems during hook-up installation to analyze the generally performed installation process and determine when the tugboat should be released. In this program, the behavior of an offshore structure was calculated using Cummin's time-domain motion equation, and the mooring system was calculated by Lumped mass method (LMM). In addition, a tugboat algorithm for hook-up installation was developed to apply the Hook-up procedure. The model used in the calculations was the barge type assuming FPSO (Floating production storage and off-loading) and has a taut mooring system connected to 16 mooring lines. The results of the simulation were verified by comparing with both MOSES, which is a commercial program, and a calculation method for restoring coefficient matrix, which was introduced by Patel and Lynch (1982). Finally, the offset of the structure according to the number of tugboats was calculated using the hook-up simulation, and the significant value was used to represent the calculation result.