CALCULATION, EXPERIMENT AND EXPERIENCE IN MERCHANT SHIP PROPELLER DESIGN

In the history of screw propellers, theory, experiment and practical experience have dominated design. The fact that propellers are still designed with reasonable success is a reflection on the designer's ability to take an informed view of the problem using all the aids to assist his intuitive ability and experience. The paper illustrates that, despite increasingly complex theory, the availability of the computer in routine procedures and the ever improving and extending sphere of model test facilities, the designers experience is still demanded in much the same proportion as hitherto. In the case of fixed pitch propellers systematic series model testing is still the most effective way of determining leading propeller dimensions. Although lifting line or lifting surface theory is then used to determine the best distribution of loading on the propeller, empirical factors derived from scale are still necessary for achievement of correct power/revolution ratio: Six-bladed propellers are also discussed as are recent systematic series model results from Newcastle University Cavitation Tunnel over a range covering loadings today common on large tankers and bulk carriers. Systematic series data demonstrate present emphasis on cavitation performance resulting from single screw propulsion on very large, high powered vessels. Current use of the cavitation tunnel as a design tool is discussed and related to the essential need discrimination and judgement as well as adequate ship/model correlation. The design objectives are somewhat different in the case of controllable pitch propellers, the ability to alter pitch and loading taking a degree of responsibility from the designer and placing the selection of best engine setting firmly on the operator. The designer, however, must deal with factors such as determination of spindle torque under extreme manoeuvering conditions. Recent work on ducted propeller systems is also discussed.

• Supplemental Notes:
  • 45 Conference Papers presented at IMAS 73, London, 4-8 June 1973, organized by the Institute of Marine Engineers. This paper is available only in a set of 6 papers in Subject Group 9: "Stern Gear, Shafting and Propellers" at $10.00.
• Corporate Authors:

  Institute of Marine Engineers

  Memorial Building, 76 Mark Lane
  London EC3R 7JN,   England 
• Authors:
  • Emerson, A
  • Sinclair, L
• Publication Date: 1973

Subject/Index Terms

• TRT Terms: Controllable pitch propellers; Ducted propellers; Propellers; Vehicle design
• Old TRIS Terms: Propeller design
• Subject Areas: Design; Marine Transportation; Vehicles and Equipment;

Filing Info

• Accession Number: 00048489
• Record Type: Publication
• Source Agency: Institute of Marine Engineers
• Files: TRIS
• Created Date: Nov 14 1973 12:00AM