Scale effect of Gate Rudder

Sasaki, Noriyuki and Atlar, Mehmet (2019) Scale effect of Gate Rudder. In: Sixth International Symposium on Marine Propulsors, 2019-05-26 - 2019-05-30.

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    Abstract

    This paper introduces a new power prediction method for an innovative propulsion system which may not be categorized as a conventional energy saving device and it has not been even fully explored so far. Yet this system, which is called “GATE RUDDER“, has been already applied for the first time on a 2400 GT container ship and full-scale sea trials were conducted successfully in November 2017 in Japan. The recent full-scale trials with this domestic container vessel have confirmed the superior performance of the gate rudder system (Sasaki 2018). However, the big discrepancy between the model test and the sea speed trial results was found when those are compared with the data of her sister ship equipped with a conventional flap rudder. After 12 month from her delivery, the voyage data revealed the fact that the difference observed in the speed trial was not negligible and surprisingly much larger difference was found based on the voyage data (Fukazawa 2018). This paper investigates the scale effect of the Gate Rudder system and concludes that the main reason of the discrepancy between the model test and full scale data can be related the scale effect associated with the drag and lift characteristics at low Reynolds numbers for both rudder blades.