Yigit Kemal Demirel

Effect of barnacle fouling on ship resistance and powering

Abstract Predictions of added resistance and the effective power of ships were made for varying barnacle fouling conditions. A series of towing tests was carried out using flat plates covered with artificial barnacles. The tests were designed to allow the examination of the effects of barnacle height and percentage coverage on the resistance and effective power of ships. The drag coefficients and roughness function values were evaluated for the flat plates. The roughness effects of the fouling conditions on the ships’ frictional resistances were predicted. Added resistance diagrams were then plotted using these predictions, and powering penalties for these ships were calculated using the diagrams generated. The results indicate that the effect of barnacle size is significant, since a 10% coverage of barnacles each 5 mm in height caused a similar level of added power requirements to a 50% coverage of barnacles each 1.25 mm in height.

Life Cycle Assessment of Marine Coatings Applied to Ship Hulls

This paper presents the methodology developed for Life Cycle Assessment (LCA) of antifouling marine coatings with regard to fouling accumulation on hulls and maintenance of ships. The methodology is based on mathematical models vis-a-vis the environmental and monetary impacts involved in the production and application of hull coatings, added fuel consumption due to fouling accumulation on ship hulls, and hull maintenance. This subject was investigated in a recently completed EU-Funded FP7 Project entitled FOUL-X-SPEL. The LCA methodology was developed using the results of the studies conducted by FOUL-X-SPEL Consortium as well as additional data provided by coating manufacturers, shipyards and shipping companies. Following the introduction of the new LCA model, a case study was carried out to show how to utilize the model using a real tanker which is assumed to be coated with two different types of existing coatings, namely a silicone-based fouling-release coating and a tin-free self-polishing antifouling paint. The total costs and emissions due to the use of different coating types were calculated for the whole life-cycle of the ship. It has been found that CO2 emission reduction due to mitigation of fouling can be achieved using a silicone-based fouling release coating while reducing the cost by means of fuel cost reductions for the ship-owners despite the additional capital expenses. The developed LCA model can help stakeholders determine the most feasible paint selection as well as the optimal hull-propeller maintenance schedules and make condition-based maintenance decisions.

Energy efficient ship operation through speed optimisation in various weather conditions

Speed optimisation or speed management has been an attractive topic in the shipping industry for a long time. Traditional methods rely on masters’ experience. Some recent methods are more efficient but have many constraints, which preclude obtaining an optimum speed profile. This paper introduces a relatively advanced model for global speed optimisation towards energy efficient shipping in various weather conditions and shows the effect when the method is employed. With this model, if a ship type, departure and destination ports and fixed ETA (Estimated Time Arrival) are given, the stakeholders can be provided with a more reasonable speed operation plan for a certain commercial route, which leads to lower fuel consumption. Weather conditions and, hence, routing plays a very important role in this process. Several case studies over different shipping conditions are considered to validate the model.

Data for: "Effect of barnacle fouling on ship resistance and powering"

Predictions of added resistance and effective power of ships were made for varying barnacle fouling conditions. A series of towing tests were carried out using flat plates covered with artificial barnacles. The tests were designed to allow the examination of the effects of barnacle height and percentage coverage on the resistance and effective power of ships. The drag coefficients and roughness function values were evaluated for the flat plates. Roughness effects of the fouling conditions on the ship frictional resistances were predicted. Added resistance diagrams were then plotted using these predictions, and powering penalties for these ships were calculated using the generated diagrams. The results indicate that the effect of barnacle size is significant, since a 10% coverage of barnacles each 5mm in height causes a similar level of added power requirements to a 50% coverage of barnacles each 1.25 mm in height. This dataset contains figures showing the digital model of 3D printed barnacles, frictional resistance coefficients of the test plates, percentage increases in the frictional resistance and effective power of ships due to biofouling, and added resistance diagrams for these ships.