Hydrodynamic Assessment of Increasing the Energy Efficiency of Trawler Propulsion with a Draft Tube
Affiliation(s)
1 Faculty of Civil and Environmental Sciences VRII, University of Iceland, Reykjavík, Iceland. 2 National Power Company of Iceland, Reykjavík, Iceland. 3 School of Marine Engineering, Technical College, Reykjavík, Iceland.
1 Faculty of Civil and Environmental Sciences VRII, University of Iceland, Reykjavík, Iceland. 2 National Power Company of Iceland, Reykjavík, Iceland. 3 School of Marine Engineering, Technical College, Reykjavík, Iceland.
ABSTRACT
The economy of the fishing industry is suffering from high fuel prices. Considerable efforts are invested in methods to increase the energy efficiency of fishing vessels and reducing the oil consumption per kilo of catch that may be as high as 0.6 to 0.7 liter oil per kilo catch. It is primarily the fact that sailing and fishing are on two very different speeds that cause these high fuel consumptions. This is called the two-speed problem and it is the trawlers that are hit hardest by it. The essence of the two-speed problem is that a hydraulic efficiency of only 28% can be expected in trawling speed, when it would be 67% if the ship is sailing at optimum speed all the time. Hydrodynamical analysis shows that an average hydraulic efficiency of only 41% can be expected for a trawler. There is no simple remedy for this, but it is possible to use a technology developed in the hydropower industry, i.e. a draft tube, or a diffuser, to recover energy that would otherwise be lost when trawling. A draft of tube the same length as the propellers diameter could mean fuel savings of 10%, a draft tube twice as long 20%. The difficulty is to find a way to get the draft tube out of the water during sailing with a vessel-specific mechanical design that is not a part of the fluid dynamics of the problem and not discussed in the paper.
The economy of the fishing industry is suffering from high fuel prices. Considerable efforts are invested in methods to increase the energy efficiency of fishing vessels and reducing the oil consumption per kilo of catch that may be as high as 0.6 to 0.7 liter oil per kilo catch. It is primarily the fact that sailing and fishing are on two very different speeds that cause these high fuel consumptions. This is called the two-speed problem and it is the trawlers that are hit hardest by it. The essence of the two-speed problem is that a hydraulic efficiency of only 28% can be expected in trawling speed, when it would be 67% if the ship is sailing at optimum speed all the time. Hydrodynamical analysis shows that an average hydraulic efficiency of only 41% can be expected for a trawler. There is no simple remedy for this, but it is possible to use a technology developed in the hydropower industry, i.e. a draft tube, or a diffuser, to recover energy that would otherwise be lost when trawling. A draft of tube the same length as the propellers diameter could mean fuel savings of 10%, a draft tube twice as long 20%. The difficulty is to find a way to get the draft tube out of the water during sailing with a vessel-specific mechanical design that is not a part of the fluid dynamics of the problem and not discussed in the paper.
Cite this paper
Eliasson, J. , Eliasson, E. and Eliasson, H. (2015) Hydrodynamic Assessment of Increasing the Energy Efficiency of Trawler Propulsion with a Draft Tube. Open Journal of Fluid Dynamics, 5, 139-144. doi: 10.4236/ojfd.2015.52016.
Eliasson, J. , Eliasson, E. and Eliasson, H. (2015) Hydrodynamic Assessment of Increasing the Energy Efficiency of Trawler Propulsion with a Draft Tube. Open Journal of Fluid Dynamics, 5, 139-144. doi: 10.4236/ojfd.2015.52016.
References
[1] Jonsdottir, H., Sparf, A.M. and Hanssen, O.J. (2005) Enviromental Benchmarking. Nordic Innovation Centre, Oslo. www.nordicinnovation.net [2] Messina, G. (2006) Some Technological Contributions to Fuel Savings in Trawlers. Conference on Energy Efficiency in Fisheries Séminaire sur les économies Dténergie à la Pêche, Brussels, 11-12 May 2006, 56.
http://energyefficiency-fisheries.jrc.ec.europa.eu/c/document_library/get_file?uuid=c6537a86-e93d-4c56-9f18-c2768cf8f928&groupId=12762 [3] Parente, J., Fonseca, P., Henriques, V. and Campos, A. (2008) Strategies for Improving Fuel Efficiency in the Portuguese Trawl Fishery. Fisheries Research, 93, 117-124.
http://dx.doi.org/10.1016/j.fishres.2008.03.001 [4] Messina, G. and Notti, E. (2007) Energy Saving in Trawlers: Practical and Theoretical Approaches. Proceedings of the International Conference on Marine Research and Transportation (ICMRT), Ischia, 28-30. [5] Vincent, B. and Roullot, J. (2006) Towed Gear Optimisation, Application to Trawls. Conference on Energy Efficiency in Fisheries Séminaire sur les économies Dténergie à la Pêche, Brussels, 11-12 May 2006, 40. [6] Sterling, D. and Klaka, K. (2006) Energy Efficient Fishing: A 2006 Review. Part B Hull Characteristics and Efficiency. Australian Government, Fisheries Research and Development Corporation, Final Report: Part B. [7] Kristensen, H.O. and Lützen, M. (2012) Prediction of Resistance and Propulsion Power of Ships. Clean Shipping Currents, 1, 6. [8] Andersson, U. (2000) An Experimental Study of the Flow in a Sharp-Heel Draft Tube. Avdelningen för Strömningslära Institutionen för Maskinteknik. Licentiate Thesis, Technical Universiy of Luleå, Luleå. [9] Elíasson, H.S. and Egilsson, J.S. (2014) Hydraulic Model (Straumlíkan) Dissertation Submitted for the Partial Fulfillment for the Degree of Engineer; Technical College, School of Marine Engineering, Reykjavík.
[1] Jonsdottir, H., Sparf, A.M. and Hanssen, O.J. (2005) Enviromental Benchmarking. Nordic Innovation Centre, Oslo. www.nordicinnovation.net [2] Messina, G. (2006) Some Technological Contributions to Fuel Savings in Trawlers. Conference on Energy Efficiency in Fisheries Séminaire sur les économies Dténergie à la Pêche, Brussels, 11-12 May 2006, 56.
http://energyefficiency-fisheries.jrc.ec.europa.eu/c/document_library/get_file?uuid=c6537a86-e93d-4c56-9f18-c2768cf8f928&groupId=12762 [3] Parente, J., Fonseca, P., Henriques, V. and Campos, A. (2008) Strategies for Improving Fuel Efficiency in the Portuguese Trawl Fishery. Fisheries Research, 93, 117-124.
http://dx.doi.org/10.1016/j.fishres.2008.03.001 [4] Messina, G. and Notti, E. (2007) Energy Saving in Trawlers: Practical and Theoretical Approaches. Proceedings of the International Conference on Marine Research and Transportation (ICMRT), Ischia, 28-30. [5] Vincent, B. and Roullot, J. (2006) Towed Gear Optimisation, Application to Trawls. Conference on Energy Efficiency in Fisheries Séminaire sur les économies Dténergie à la Pêche, Brussels, 11-12 May 2006, 40. [6] Sterling, D. and Klaka, K. (2006) Energy Efficient Fishing: A 2006 Review. Part B Hull Characteristics and Efficiency. Australian Government, Fisheries Research and Development Corporation, Final Report: Part B. [7] Kristensen, H.O. and Lützen, M. (2012) Prediction of Resistance and Propulsion Power of Ships. Clean Shipping Currents, 1, 6. [8] Andersson, U. (2000) An Experimental Study of the Flow in a Sharp-Heel Draft Tube. Avdelningen för Strömningslära Institutionen för Maskinteknik. Licentiate Thesis, Technical Universiy of Luleå, Luleå. [9] Elíasson, H.S. and Egilsson, J.S. (2014) Hydraulic Model (Straumlíkan) Dissertation Submitted for the Partial Fulfillment for the Degree of Engineer; Technical College, School of Marine Engineering, Reykjavík.