Propulsion Experiments with a Deep Tunnel Planing Hull

Abstract

Resistance and self-propulsion data are presented for Model 5048 fitted with tunnels equal in depth to basic propeller diameter. The relative merits of seven combina tions of LCG posi tion , propeller diame ter and trim tabs are disc ussed. A forward LCG pos iti on offe rs the bes t comb ina tion of draf t and shaf t power. Comparisons are also made wi th the sam e hull without tunnels and with two sets of shallow tunnels. The 100 percent tunnel is inferior to both shallower tunnels in draf t and power requirements , but it gives superior propel l e r pro tec tion for beach in g opera ti ons. The 65% tunnel requ ires the least draft and gives good propeller protection , but it requires more power than the 40% tunnel. ADMINIST RATIVE INFOR MATION This report was authorized and funded by the Naval Insh ore Warfare Craf t Off ice (Code 114) of the Sys tems Develop men t Depar tmen t , David W. Taylor Naval Ship R~D Cen ter , which prov ides Techn ical Man agemen t for the Naval I nshore Warfare Craf t P rogram , SSW-02 (previously the Special War fare Craft Program , S38-20X). The Pr in cipal Develop men t Acti vi ty is the Naval Sea Sys tem s Command wit h program mana gemen t in the Adv anced Te chnolo gy Sys tem s D ivisi on (SF~A 03221). Program funding is under element 6.3586 N. This specific task was funded under center work unit 1-1140-606. 1 J-______ __ UNIT S U .S. customary units were used for the ori ginal measurements and calcula tions. SI (Metric) equivalents of US units are given where they first occur in the text and elsewhere if required for clar ity. U .S. uni ts are used alone when their SI equivalents have prev iously been given an d where the un it pe rfor ms an adjec tival function , as in "6 inch propeller ". This usage has been adopted to facilitate cross-referencing between this and previous reports in the tunnel-hull series. The appended da ta tables , prepared bef ore the adop tion of SI units , have not been revised to incorporate SI equivalents due to time and cost constraints.

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