What are factors on which squat of ships will depend?

Factors affecting the actual value of  squat will vary considerably but could expect to include any or all of the following:
  1. Draught/depth of water ratio. A high ratio equates to a greater rate of squat.
  2. The position of the longitudinal centre of buoyancy (LCB) will determine the trimming effect and have a direct relation to the squat value.
  3.  High engine revolutions can expect to increase stern trim.
  4. The speed of the vessel is related to the value of squat in that the value is influenced by speed.The faster the ship moves the greater the squat value.
  5. The type of bow fitted effects the wave making and pressure distribution on the under water volume.
  6. The length/breadth ratio can cause an increase or decrease of the squat value, i.e. short-tubby ships tend to squat more, than the longer narrow beam vessel.
  7. The breadth/channel width ratio affects the squat value. A high ratio causing an increased value of squat.
  8. Vessels with a large block coefficient Cb will experience greater effects from squat.
  9. Greater effects of squat are experienced when a vessel is trimmed by the bow than by the stern.
  • Ship’s speed (Main Factor). Squat is directly approximately proportional with the speed squared.
  • Depth of water: inversely proportional.
  • Confines of the channels: inversely proportional.
  • Block Coefficient (ratio of the immersed volume of the ship relating to the water line length, breadth and draft): directly proportional.
  • Blockage Factor (immersed cross-section of the ship’s mid-ship section divided by the cross-section of the canal or river): directly proportional.


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