RECENT UNITED STATES COAST GUARD EFFORTS TO IMPROVE ICEBREAKING EFFICIENCY

The most effective way to improve the icebreaking efficiency of a ship is to reduce the ice resistance. Model tests of the Polar Class icebreaker and the 140-foot icebreaking tug were conducted to determine the resistance in level ice as a function of ice thickness, ship speed, and hull-ice friction factor. Regression analysis of the model test data resulted in nondimensional equations from which full-scale resistance predictions can be made. A means for estimating the effects of hull-ice friction on resistance is provided. A test program with the Polar Class model was also conducted to determine which areas of the hull are subject to the highest ice loading and to measure the icebreaking resistance as a function of the coverage of these areas with low friction surfaces. Results show that coating less than 20% of the underwater body can achieve approximately 85% of the reduction in resistance possible with coating the entire hull. Model tests of the 140-foot icebreaking tug with an air bubbler system were conducted to determine the effectiveness of this system and to determine the optimum air flow rate. The test results show a significant drop in resistance (up to 38% at 1 knot with a flow of 16,800 SCFM) due to the action of the air bubbling system. An optimum capacity exists, but it is greatly affected by the design of the air piping system.

• Supplemental Notes:
  • Presented at the Spring Meeting/STAR Symposium, New London, Connecticut, April 26-29, 1978. Available only in bound proceedings.
• Corporate Authors:

  Society of Naval Architects and Marine Engineers

  601 Pavonia Avenue
  Jersey City, NJ  United States  07306-2907
• Authors:
  • Lecourt, E J
  • Major, R A
  • Thomas, H L
  • Naegle, J N
• Publication Date: 1978

Subject/Index Terms

• TRT Terms: Fluid resistance; Hulls; Ice; Icebreakers; Icebreaking; Loads; Resistance (Mechanics); Ship motion; Ships; Thickness; Tugboats
• Uncontrolled Terms: Hull resistance
• Old TRIS Terms: Ice loads; Ice resistance; Ice thickness; Model testing
• Subject Areas: Marine Transportation; Vehicles and Equipment;

Filing Info

• Accession Number: 00173995
• Record Type: Publication
• Source Agency: Society of Naval Architects and Marine Engineers
• Report/Paper Numbers: No. 22
• Files: TRIS
• Created Date: May 3 1978 12:00AM