DIRECTIONAL STABILITY AND CONTROL OF SHIPS IN WAVES

The stability and oscillatory motions of ships (automatically steered and unsteered) in the horizontal plane were examined on a digital computer for the case of regular following seas. Available hydrodynamic data for Series 60 hull forms were used. Analysis of directional stability was made for the case of zero encounter frequency (i.e., the ship runs at high speeds equal to the wave celerity.) The ship (which is hydrodynamically stable without automatic control in calm water) is directionally unstable in following seas except for the small region near the ascending node of the waves. Addition of automatic control can give the ship directional stability when it is located on the wave trough, but not when it is located on the wave crest. At relatively high frequency (i.e., at low speeds in following seas), the rudder and control system are almost incapable of reducing oscillatory motion. Violent rudder activity in following seas can be decreased by reducing the yaw-rate-gain control constant and by increasing the rudder-response-time constant.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/00224502
• Corporate Authors:

  Society of Naval Architects and Marine Engineers

  601 Pavonia Avenue
  Jersey City, NJ  United States  07306-2907
• Authors:
  • Eda, H
• Publication Date: 1972-9

Media Info

• Features: References;
• Pagination: p. 205-218
• Serial:
  • Journal of Ship Research
  • Volume: 16
  • Issue Number: 3
  • Publisher: Society of Naval Architects and Marine Engineers
  • ISSN: 0022-4502
  • EISSN: 1542-0604
  • Serial URL: https://onepetro.org/jsr

Subject/Index Terms

• TRT Terms: Directional stability; Oscillation; Rudders; Ship motion; Steering
• Old TRIS Terms: Course keeping qualities; Course stability; Rudder oscillation; Steering characteristics
• Subject Areas: Marine Transportation; Vehicles and Equipment;

Filing Info

• Accession Number: 00041850
• Record Type: Publication
• Source Agency: Society of Naval Architects and Marine Engineers
• Files: TRIS
• Created Date: Apr 6 1973 12:00AM