Surface Piercing Propellers for Displacing Vessels

Surface piercing propellers had several successful applications into the field of high-speed vessels; rarely, however, have been used for conventional dis-placing vessels, where they are also named “PSP” (Partially Submerged Pro-pellers). This paper deals with the application of a PSP on a new livestock carrier dis-placing about 5000 tons which has been successfully trading since 1998. After a brief introduction, where the state of the art is described, a few theo-retical issues are discussed, and short description of the research and design work is presented. The results of various other tests performed with PSP both with models and in full scale are also illustrated and briefly discussed; these have been then compared with those obtainable on conventional cases. Risks of possible undesired phenomena and benefits related to the applica-tion of PSP in large scale on displacing ships of different type and size are also dealt with and an outlook of investigations recently carried out on a peculiar application of PSP is also illustrated.