Development of a bow wash system for an ice going vessel

• Main Author: Heikkilä, Tommi Kalevi
• Other Authors: Laukia, Kari, Insinööritieteiden korkeakoulu, School of Engineering, Sovelletun mekaniikan laitos, Kujala, Pentti, Aalto-yliopisto, Aalto University
• Format: Master Thesis
• Language: Finnish
• Published: 2012
• Subjects: bow wash; bow thruster; channel resistance; model test; tanker; power estimation; feasibility; keulahuuhtelu; työntölaite; rännivastus; mallikoe; tankkeri; tehonarviointi; toteutettavuus; Arctic
• Online Access: https://aaltodoc.aalto.fi/handle/123456789/100387

Vessel's channel resistance has become an important factor in determining vessel's ice class after the year 2003, when the propulsion power requirement of Finnish-Swedish ice class rules started to be defined by the channel resistance. Due to the present day high fuel oil costs and due to the emission restrictions in near future, it is important to try to improve the fuel economy of ships. The aim of this master's thesis is to research the technical-and economic feasibility of a bow wash system concept for an ice going vessel. The system has been patented by Aker Arctic. The technical feasibility is determined by researching the suitability of different commercial solutions for the requirements of the bow wash system. The second objective for the technical feasibility study is to determine the required power for the bow wash system through model tests. The economic feasibility of the system is evaluated by the repayment time, which is determined by assessing the difference of purchase prices and achievable fuel oil cost savings. The system is applied to an Aframax class tanker. From the executed model tests it can be seen, that the required power for the system is 1500 kW. With this amount of power a 15 % reduction of channel resistance for the applied vessel type in 1,4 m thick channel has been observed. Even larger reduction could be achieved, if a more powerful system was used, but this phenomenon could not be verified with the model tests. From the results of the model tests, it can also be seen, that the efficiency of the system improves, if the diameter of the water stream outlet is enlarged. The benefits in fuel oil costs vary between 10 000 and 300 000 Euros, according to variations in severity of the winter and route of the vessel. Therefore the calculated repayment times for the initial investment vary between two and five years. The severity of the winter is the factor, which defines the length of the repayment time. The effect of the two studied route alternatives is considerably lesser, even though ...