Tudo que encontrei sobre os flapped rudders foi o trecho abaixo, da pg 16:
“There are several types of movable flap rudders, such as Becker, Barke, Ulstein, Jastram and Promac Stuwa. At die end of the rudder blade is a movable flap, controlled by linkage, comprising about 20- 30% of the total rudder area. Maximum helm angle differs by type and is about 40-50°. Each type of flap rudder has its own specific characteristics. The flap angle is a function of the helm angle and with a Becker rudder, for instance, it will be about three times the main rudder angle for the lower range and decreasing to a factor of two for the upper range rudder angles. Maximum lift, which is achieved at a rudder angle of approximately 30°, is increased by 60-70% compared with a conventional rudder of the same shape, size and area. Sideways thrust ranges up to 50% of ahead thrust. At maximum rudder angle the propeller stream will, depending on rudder size and balance, be diverted approximately 90°. At speed the vessel can turn very quickly and speed will drop fast. When dead in the water the vessel can nearly turn on the spot. Performance of the rudder when the tug has speed astern is about the same as that of an unflapped rudder. Tugs may have more than one movable flap rudder behind a nozzle.”
Voce poderia especificar em qual página (ou número do slide do curso) do livro está o trecho que deu origem à sua dúvida?