EYE ON DESIGNVoith Schneider PropulsorThe Maritime Research Institute Netherlands undertakes the ? rst-ever investigation into VSP-induced hull-pressure ß uctuationsBY RIEN DE MEIJ, MARINFor the ? rst time an investigation into tan. The three sister ships, Guy V. Mo- The goal of these tests was to deter- measured hull excitation caused by the Voith Schneider Propulsor-induced linari, Sen. John J. Marchi and Spirit of mine the best propulsor con? guration, two active aft VSPs is low. hull-pressure ? uctuations has been car- America, can carry 4,427 passengers which requires the lowest shaft power The highest levels are measured on ried out. This investigation was part of and have a crew of 16. The double- at design speed, focusing on the best di- the center line of the ship, which is due a New York City Department of Trans- ended ferries have a propeller gondola, rection of rotation, thrust vector direc- to interaction between the portside and portation (NYCDOT) study to retro? t conventional propulsion system and tion and power distribution between the starboard VSP units. the Molinari Class Ferries, which op- one center skeg at both ends. fore and aft VSP units. This observation resulted in recom-erate to the world-renowned Staten Is- The study started by adapting the cur- With the selected con? guration, pro- mendations for a minimum spacing be-land, with Voith Schneider Propulsion rent hull lines for a propulsion arrange- pulsor cavitation observations and mea- tween the two aft propulsors. (VSP). ment consisting of four VSP26R5 units. surements of the propulsor-induced hull The main advantage of the tested con-One of the objectives was to investi- After the lines were optimized, a 7.3 pressure ? uctuations were carried out in ? guration, compared to the existing set gate the modi? cation in terms of energy m long ship model was manufactured the Depressurized Wave Basin. Cavita- up, is the increased maneuverability of ef? ciency. and a model test program for the opti- tion observations and measurements the vessel. The Staten Island Ferry carries more mization of the Voith Schneider propul- were performed on the portside aft pro- These results supported the NYCDOT than 21 million passengers annually be- sor arrangement was carried out in the pulsor, with all four VSPs active. in its decision-making for future devel-tween Staten Island and Lower Manhat- Shallow Water Towing Tank. It was concluded that the level of the opments of the Staten Island Ferry.MARIN’s Depressurized Wave Basin was the site for a test of the best propulsor con? guration for the Staten Island ferries.16 Maritime Reporter & Engineering News • JANUARY 2014MR #1 (10-17).indd 16 1/7/2014 10:29:17 AM