Impact of Air Cavity Technology on Ship Drag Reduction: Experience from Research Studies

A series of recent studies looking into the issues raised by implementation of IMO CO2 regulations have shown that air supply techniques are probably the last-hope offer for merchant ships to achieve the prescribed 25-30% reduction of the energy efficiency design index (EEDI) without substantial reduction of speed. The Krylov State Research Centre has introduced and continuously developed the air cavity (ACS) technology. At the same time, whilst an alternative method of viscous drag reduction based on supply of air bubbles under ship bottom is being intensively explored. Great experience of KSRC in air-cavity ships as well as some experience in research studies on air bubble lubrication of hull bottom enable to formulate and analyze the scientific problems which arise in both areas of development. The efficiency of air cavity technologies is demonstrated by analysis of two projects, a tanker and a containership, with consideration of both hydrodynamic and economic prospect.