CALCULATING SQUAT--A PRACTICAL APPROACH

The Author, of Liverpool Polytechnic, discusses the calculation of squat, with the object of showing how the squat of ships in shallow open waters may be calculated in the same way as that of ships moving in shallow laterally-restricted channels. In this latter case, squat can be roughly expressed as a function of ship-speed, block coefficient, and "blockage factor" (the ratio of the ship's maximum underwater cross-sectional area to the gross cross-sectional area of the waterway); to apply such expressions to waters without side restrictions, it is necessary to find an "effective width" or "width of influence" for the water through which the ship passes. The problem is examined in detail for both full-form and other ships with the assistance of experimental data from a number of ships, and formulae are derived and proposed for the calculation of squat in actual ships and for its prediction from models. For calculating the effective width of influence of a ship in shallow waters without side restrictions, a simple formula based on electrical-analogue experiments is proposed. Order from: BSRA as No. 47,693.

• Corporate Authors:

  Nautical Institute

  Alderman's House, Alderman's Walk
  London EC2M 3UU,   England 
• Authors:
  • Barrass, C B
• Publication Date: 1977

Media Info

• Features: References;
• Pagination: 19 p.

Subject/Index Terms

• TRT Terms: Maneuvering; Ship motion
• Uncontrolled Terms: Blockage; Squat
• Old TRIS Terms: Restricted water operation; Shallow water maneuvering
• Subject Areas: Marine Transportation; Safety and Human Factors; Vehicles and Equipment;

Filing Info

• Accession Number: 00173718
• Record Type: Publication
• Source Agency: British Ship Research Association
• Files: TRIS
• Created Date: Apr 26 1978 12:00AM