Water is modeled as a spherical top with a hard, convex tetrahedral surface. In its collisions, water transfers linear and angular momentum according to the usual two-body kinematics; however, rotational energy transfer is diminished from the hard-body value since portions of the surface of water are blocked due to pre-existing hydrogen bonds. Owing to the bottleneck in transfer of rotational energy, convective effects normally important for water at subcritical densities are conjectured to be significant at densities where water forms hydrogen bond networks. The present theory is compared to experimental and computer simulation studies of orientational and angular momentum relaxation times, and the agreement or lack thereof is analyzed.