SPEED OF SHIPS IN RESTRICTED NAVIGATION CHANNELS

Ship model experiments confirm that orthodox screw-driven craft attain an apparent maximum or "barrier" speed in navigation channels of restricted width and depth, irrespective of available engine power. This speed is primarily a function of blockage ratio (the relationship between cross-sectional area of the ship to that of the channel). It occurs when conditions alongside become critical at the maximum section; discharge onto the screw is thereby controlled and ship speed becomes limiting. A direct hydraulic jump develops near the stern. A bow-screw arrangement permits acceleration beyond the limiting speed since free flow onto the screw is no longer prevented by critical conditions which now occur downstream. Factors studied during experimentation include ship squat, thrust, power, screw revolutions, water-surface profiles, and water velocities. A simple two-dimensional theory demonstrates the development of critical conditions around the ship.

• Corporate Authors:

  American Society of Civil Engineers

  345 East 47th Street
  New York, NY  United States  10017-2398
• Authors:
  • SCHOFIELD, R B
• Publication Date: 1974-5

Media Info

• Features: References;
• Pagination: p. 133-150
• Serial:
  • Journal of Waterways, Harbors & Coast Eng Div
  • Volume: 100
  • Issue Number: WW2
  • Publisher: American Society of Civil Engineers

Subject/Index Terms

• TRT Terms: Channels (Waterways); Maneuvering; Navigation; Ship motion
• Uncontrolled Terms: Blockage; Squat
• Old TRIS Terms: Narrow channel navigation; Restricted water operation; Shallow water effects; Shallow water maneuvering
• Subject Areas: Marine Transportation; Safety and Human Factors; Vehicles and Equipment;

Filing Info

• Accession Number: 00057116
• Record Type: Publication
• Source Agency: American Society of Civil Engineers
• Report/Paper Numbers: Paper 10539 Proceeding
• Files: TRIS
• Created Date: Jul 31 1974 12:00AM