Air cavity and air lubrication system ship having stern shape of stepped form around the propeller

摘要

pThe present invention relates to an air cavity and air lubrication system ship having a stern shape of stepped form around the propeller and the ship comprises: ship bottom dams and stern dams (stern steps) which are attached and secured at predetermined intervals in the width direction of the hull on the ship s bottom apart from the bow and on the stern and which extend in the length direction of the hull so as to form a plurality of air cavities; a plurality of air supply tubes which are installed perpendicularly on the ship so as to supply air to the air cavities and which have aperture adjusting valves while also being equipped with air supply machinery for supplying compressed air; slots of which a plurality are formed at predetermined intervals in the length direction of the ship bottom dams and which are formed in the ship bottom dams in such a way as to not only allow air communication between air cavities but also to supply some air to the ship s sides; and steps which are provided to the rear of the rudder while constituting the discharge end of the stern dam (stern step) so as to block the inflow of discharged air towards the propeller by inducing a continuous vacuum by causing speed differences in the wake of the propeller. According to the present invention because of the stern shape of stepped form it is possible to obtain the advantage of reduced carbon dioxide production because the air and the air bubbles that flow in from the front of the propeller are blocked and unable to flow in towards the propeller and at the same time are discharged smoothly to the rear of the propeller because of the use of the vacuum which is to say the suction force generated at the steps due to the high speed wake of the propeller and thus the reversing efficiency is improved and the air lubrication reduces the surface area of friction between the hull and the water and minimises frictional resistance./p