PROPULSION AND CAVITATION INVESTIGATION ON 230,000 TONS DWT TANKERS--FULL SCALE AND MODEL EXPERIMENTS

In cooperation with Uddevailavarvet AB-(UV) the Swedish State Shipbuilding Experimental Tank (SSPA) has carried out a comprehensive model investigation concerning propulsion and cavitation for a series of 230,000 dwt tankers. The investigation includes the study of flow conditions and wake distributions, propeller and propulsion characteristics, cavitation patterns and cavitation erosion together with propeller induced hull pressure under cavitating and noncavitating conditions. Conventional hulls as well as hulls fitted with different stern fin arrangements have been investigated and different propeller designs have been compared. The flow studies and cavitation experiments were carried out in SSPA's new cavitation tunnel, which allows propeller cavitation studies behind a complete ship model. In addition to conventional speed trials, the full scale experiments included photographing cavitation patterns under different ship propeller loading conditions. The behavior of the propellers with regard to cavitation erosion was studied. In cooperation with Det norske Veritas also propeller induced hull pressures, propeller mean thrust and thrust variations were measured. The results which concern propulsion and cavitation are summarized and anlayzed in the present paper. Special attention is paid to the correlation of model and ship results.