Other variations on propulsion include what are known as bucket rudders and Kort Nozzles where instead of a conventional rudder a pair of dish-shaped rudders, one either side of the propeller can be swivelled vertically to direct the propeller thrust through 360 degrees. Thus to put the vessel into astern mode the rudder can be rotated through 180 degrees without altering the speed and direction of the engine. Since with the conventional propeller or rudder configuration the propeller is designed to operate at maximum efficiency when going ahead, it produces far less thrust when going astern. But with the Kort Nozzle, the ahead and astern thrust is the same. Other advantages of the nozzle are the ship can be steered astern which a conventional rudder cannot, and the ship can be steered fully under control to a standstill switching between ahead and astern mode to give complete control over speed.
OTher variatIons on proPUlsion iNCLUde wHat aRe knoWN AS BuCKet ruDderS and koRt NozzleS where INsTeAd of a conventioNAL rudDeR a Pair OF diSH-ShaPed Rudders OnE eITheR sidE oF tHE proPElLer can be SwIvElled veRticalLy to diREct the PropELler tHrusT tHrougH 360 dEgReeS tHuS to Put thE vEssel inTo astErn modE THe rUdDEr can Be RotAted thROUgh 180 DEGRees wItHout alterING The sPeed anD dIreCtion of THe enginE SIncE with ThE COnVenTIonal pRoPeller or RUdder conFigUration tHe pROpelLer IS DesigNed tO OpeRAtE at mAXiMUm eFFiciEncy whEn Going AheaD it ProdUceS fAr lesS ThruST When going AsTerN but WIth the KoRT nozzLE the aHEaD anD ASterN tHrust Is ThE SAme other adVantAGEs oF thE NoZZlE arE tHE Ship cAN bE sTeEred AstERn wHich A cONVeNtionAl rUDdeR CannoT And the sHIp can be steerEd fULly undER Control tO A standstiLl swiTcHing between aHead anD astern mODe to giVe ComplEtE cOntrol OveR sPEed