The free-stream or open-water characteristics of rudders, in conjunction with certain corrections to allow for the absence of the hull and propeller, are being increasingly used in rudder design. The Authors present an account of wind-tunnel tests to investigate the free-stream characteristics of semi-balanced skeg rudders. Three skeg rudders of different form, typical of the rudders fitted to many modern ship-types, were investigated. The experimental techniques are described, and the results are presented as lift, drag, and normal force coefficients and as centres of pressure, for the rudder/skeg combination and for the rudder alone. Results are also given of supplementary tests, on the influence of gap flow, in which the gaps between the rudder and skeg were sealed. Comparisons were made between the characteristics of the skeg rudders and their simulated "all-movable" rudder equivalents. The results are discussed in detail, with a number of conclusions and recommendations. The experiments contribute to a better understanding of the performance of the skeg rudder, but further investigation is needed to predict the most effective combination of rudder, skeg, and gap for a given application. The paper also includes an illustrated description of the five-component dynamometer specially designed for these tests and the subject of a 1976 Report from Southampton University.

  • Availability:
  • Supplemental Notes:
    • This paper was presented at a R.I.N.A. meeting in April 1979. The tests described were carried out in a low-speed wind-tunnel at the University of Southampton.
  • Corporate Authors:

    Royal Institution of Naval Architects

    10 Upper Belgrave Street
    ,   United States 
  • Authors:
    • Goodrich, G J
    • Molland, A F
  • Publication Date: 1979-11

Media Info

  • Features: References;
  • Pagination: p. 285
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00310891
  • Record Type: Publication
  • Source Agency: British Ship Research Association
  • Report/Paper Numbers: Technical Papers
  • Files: TRIS
  • Created Date: May 7 1980 12:00AM