gyradius

plural gyradii

1. engineeringRadius of gyration.

   The roll, pitch and yaw gyradii (k₄₄, k₅₅ and k₆₆) were determined using the pendulum method by swinging the model in the air.

   1999, J. de Kat, W. Thomas III, “Extreme Broaching, Rolling and Capsizing-Model Tests and Simulations of a Steered Ship in Waves”, in Twenty-Second Symposium on Naval Hydrodynamics, National Academy Press, page 363

   2 more examples

   1966, Bruce Jennings Muga, Experimental and Theoretical Study of Motion of a Barge as Moored in Ocean Waves, Department of Civil Engineering, University of Illinois, page 17, It should be noted that the vertical center of gravity (VCG), the longitudinal gyradius, and the natural pitch period do not agree with those required to simulate the full-scale prototype.

   Weight distribution may be considered in any desired plane, usually in longitudinal and transverse senses. It is measured by the moment of inertia and is usually expressed as the gyradius which relates the moment of inertia to displacement.[…]Thus a large gyradius, longitudinal or transverse, tends towards easy motion and is desirable in terms of comfort. In passing it might be observed that the need for a very minimum longitudinal gyradius has become an article of faith among racing sailors.

   2008, Peter Bruce, Adlard Coles' Heavy Weather Sailing, 6th edition, McGraw-Hill, page 8