■■■Fuel saving devices are categorized on 4-5 years,since a new propeller is required. absorbed at a higher rpm,and the engine percentage of efficiency improvement:up to With the help of modern hydrodynamic operation is shifted out of the"red"area. 5%,up to 10%and up to 15%. software,more reliable cavitation predictions Fuel savings,after trailing edge cutting, are made.This way higher power densities can of 6%to 8%are reported.Payback period is UP TO 5%IMPROVEMENT be allowed,and thus a lower blade area can 2 months. PROPELLER POLISHING AND/OR REPAIR OF be applied.A reduction in frictional losses can EDGE DAMAGE result in efficiency improvements up to 3% UP TO 15%IMPROVEMENT Propeller polishing in combination with With the combination of tip rake and a By conversion of an open propeller to a ducted repair of edge damage easily increases the lower blade area it is possible to realize fuel propeller,efficiency gains up to 15%are propeller's operating efficiency with 2%to savings up to 5%.Payback period is 3 years. established. 4%.The Return On Investment(ROI)period The idea of surrounding a propeller by a is quite short.After 1 to 3 months,the UP TO 10%IMPROVEMENT nozzle is already very old.Today about 25% maintenance costs are already paid back. MODERN DESIGN PROPELLER WITH of all Wartsila controllable pitch propellers are INCREASED DIAMETER AND LOW SPEED running in a nozzle. MODERN DESIGN PROPELLER In general a larger propeller diameter in In an accelerating nozzle the water speed A redesign of the current propeller,based combination with a low rotational speed leads at the propeller is higher then that of the on the state-of-the-art,without optimizing to an improvement in efficiency.The axial open propeller.The increase in axial velocity the boundary conditions like propeller speed losses will be reduced.Basically we can apply reduces the propeller load especially for and diameter.can lead to an improvement of this for all ship/propeller types. heavily loaded propellers.This then leads approximately 5%. In case the diameter can not be increased.to an increase in overall performance of Tip rake reduces the local rotation around sometimes a larger number of blades(5 or the propeller and nozzle compared to that the tip.For large fixed pitch propellers the 6)provides a solution for further optimization. of a propeller alone.Additionally.the nozzle positive effect can be up to 3%.The ROI is Payback period is 1.5 to 2.5 years. generates forward thrust caused by the EFFICIENCY RUDDER The efficiency rudder is a successful new Extemal profile development.Axial and rotational losses in the slip stream of the hub are eliminated by the 效 torpedo,which is fitted in between the propeller Internal profile and the rudder.Highly loaded propellers and ships with speeds exceeding 15-20 knots, Better flow around nozzle can benefit from an efficiency rudder.For new -Curved exterior Curved interior building vessels it can be attractive since a rudder and propeller is needed anyway.For Flow pattern HR nozzle the retrofit market the investment is quite large,and therefore the Retum On Investment exceeds a period of 5 years. PROPELLER-ENGINE INTERACTION Vessels equipped with a fixed pitch propeller HR-nozzle:No flow separation at the outside of the nozzle. can suffer from a so called heavy running propeller.The terminology is somewhat Flow pattern 19A or 37 nozzle misleading;the propeller loading and engine characteristics are not matching. 2) The propeller curve crosses the load limit of the engine before full power is reached. As a consequence the engine is overloaded. leading to increased fuel consumption as well Conventional nozzle:Flow separation. as increased wear of internal engine parts. Conventional propeller LIPS tip rake propeller A pitch modification of the propeller can Advantage of LIPS high efficiency(HR)nozzle design. design. be conducted.This way the same power isInternal profile External profile Flow pattern HR nozzle Flow pattern 19A or 37 nozzle Better flow around nozzle - Curved exterior - Curved interior HR-nozzle: No flow separation at the outside of the nozzle. Conventional nozzle: Flow separation. Advantage of LIPS high effi ciency (HR) nozzle. Conventional propeller design. LIPS tip rake propeller design. 4-5 years, since a new propeller is required. With the help of modern hydrodynamic software, more reliable cavitation predictions are made. This way higher power densities can be allowed, and thus a lower blade area can be applied. A reduction in frictional losses can result in effi ciency improvements up to 3%. With the combination of tip rake and a lower blade area it is possible to realize fuel savings up to 5%. Payback period is 3 years. UP TO 10% IMPROVEMENT MODERN DESIGN PROPELLER WITH INCREASED DIAMETER AND LOW SPEED In general a larger propeller diameter in combination with a low rotational speed leads to an improvement in effi ciency. The axial losses will be reduced. Basically we can apply this for all ship/propeller types. In case the diameter can not be increased, sometimes a larger number of blades (5 or 6) provides a solution for further optimization. Payback period is 1.5 to 2.5 years. EFFICIENCY RUDDER The effi ciency rudder is a successful new development. Axial and rotational losses in the slip stream of the hub are eliminated by the torpedo, which is fi tted in between the propeller and the rudder. Highly loaded propellers and ships with speeds exceeding 15-20 knots, can benefi t from an effi ciency rudder. For new building vessels it can be attractive since a rudder and propeller is needed anyway. For the retrofi t market the investment is quite large, and therefore the Return On Investment exceeds a period of 5 years. PROPELLER - ENGINE INTERACTION Vessels equipped with a fi xed pitch propeller can suffer from a so called heavy running propeller. The terminology is somewhat misleading; the propeller loading and engine characteristics are not matching. The propeller curve crosses the load limit of the engine before full power is reached. As a consequence the engine is overloaded, leading to increased fuel consumption as well as increased wear of internal engine parts. A pitch modifi cation of the propeller can be conducted. This way the same power is absorbed at a higher rpm, and the engine operation is shifted out of the “red” area. Fuel savings, after trailing edge cutting, of 6% to 8% are reported. Payback period is 2 months. UP TO 15% IMPROVEMENT By conversion of an open propeller to a ducted propeller, effi ciency gains up to 15% are established. The idea of surrounding a propeller by a nozzle is already very old. Today about 25% of all Wärtsilä controllable pitch propellers are running in a nozzle. In an accelerating nozzle the water speed at the propeller is higher then that of the open propeller. The increase in axial velocity reduces the propeller load especially for heavily loaded propellers. This then leads to an increase in overall performance of the propeller and nozzle compared to that of a propeller alone. Additionally, the nozzle generates forward thrust caused by the Fuel saving devices are categorized on percentage of effi ciency improvement: up to 5%, up to 10% and up to 15%. UP TO 5% IMPROVEMENT PROPELLER POLISHING AND/OR REPAIR OF EDGE DAMAGE Propeller polishing in combination with repair of edge damage easily increases the propeller’s operating effi ciency with 2% to 4%. The Return On Investment (ROI) period is quite short. After 1 to 3 months, the maintenance costs are already paid back. MODERN DESIGN PROPELLER A redesign of the current propeller, based on the state-of-the-art, without optimizing the boundary conditions like propeller speed and diameter, can lead to an improvement of approximately 5%. Tip rake reduces the local rotation around the tip. For large fi xed pitch propellers the positive effect can be up to 3%. The ROI is