Wideband passive mechanical mounting systems for disk drives on boats in rough seas

The paper addresses the problem of wideband mechanical isolation of some oceanographic computer systems with magnetic and optical disk drives in boats with large translational and rotational motions in rough seas. Isolation is required against a wide spectrum of vibration due to propeller cavitation and engine dynamics, and shock due to hull slams and docking. Troubles such as a head crash can occur. Such troubles are difficult to predict not only because of the complex variety of wave trains in a "rough" sea, but also because of disk drive specifications that are inappropriate. More than a decade of experience has shown that there is no such widespread problem for larger ships. The shipboard frequencies of structural vibration (usually less than 100 Hz) are generally much lower than the resonant mechanical frequencies of computer systems with magnetic disk drives which, with some exceptions, are above 2 kHz. Moreover, shocks and ship motions of larger oceanographic vessels are of less consequence.