When predicting full-scale resistance from model tests, the scaling laws used to extrapolate the results are not particularly easy to apply. To calculate the resistance of a ship, the stresses at the ship's surface must be resolved into normal and tangential components, respectively comprising the pressure resistance and the drag or skin friction. The pressure resistance can be determined by measuring the local pressure at several points on the ship or model surface with appropriate pressure gauges. The tangential stress can be measured by floating-element friction gauges or Preston tubes. However, this type of resistance measurement is not sufficient for solving the double scaling laws, for which the components of resistance must be separated into those due viscosity and to free-surface phenomena. Since Reynolds number and Froude's law respectively govern both of these, the Author presents numerous expressions for calculating resistance components by these means, including a method of calculating viscous resistance from measured velocities. Order from: BSRA as No. 47,721.

Media Info

  • Features: References;
  • Pagination: 23 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00173669
  • Record Type: Publication
  • Source Agency: British Ship Research Association
  • Report/Paper Numbers: Paper No. 4 Proceeding
  • Files: TRIS
  • Created Date: Apr 26 1978 12:00AM