Method for reducing frictional resistance of hull, frictional resistance reducing ship using such method, and method for analyzing ejected air-bubbles from ship

A frictional-resistance reducing ship (1), said ship having a hull (2), stem portion (4), and bottom (5), characterized in that

• said ship (1) comprises a micro-air-bubble ejection port (10) located adjacent to the starting point of a stream line (F.L.) of water and located at a position where the static pressure is low,
• said stream line (F.L.) being directed to said bottom (5) along the surfaces of both sides of said hull (2) from the submerged shallow position at said stem portion (4) of said hull (2), and
• said micro-air-bubble ejection port (10) being connected with a pressure air source (13) via an air line (16),
• wherein micro-bubbles, each having an average diameter which is set at approximately 1 mm, are ejected from said micro-air-bubble election port (10).

A frictional-resistance reducing ship (1), said ship having a hull (2), stem portion (4), and bottom (5), characterized in that

• said ship (1) comprises a wave conduit (24) for taking in a stem-broken-wave (27) produced at said stem area (4) of a ship while cruising,
• said wave conduit (24) comprising an intake (25) opened forward for taking in said stem-broken-wave (27) and a discharge opening (26) opened rearward for discharging said stem-broken-wave (27) taken in,
• said intake (25) being located adjacent to the starting point of a stream line (F.L.) of water and located at the position where the static pressure is low, said stream line (F.L.) being directed to said bottom (5) along the surfaces of both sides of said hull (2) from the submerged shallow position at said stem portion (4) of said hull (2), and
• said wave conduit (24) being downward obliquely oriented so as to direct said stem-broken-wave (27) taken to the flow direction of said stream line (F.L.) in order to place said stem-broken-wave (27) on said stream line (F.L.).