Design of a stable floating platform for air-sea interaction measurements

Abstract

The design of an oceanographic platform can be defined as the rational specification of the platform dimensions and geometry. This specification is usually the result of an iterative process which compares the platform performance with the objectives to be reached and the logistic constraints to be met. This report describes such an exercise. The scientific objectives - measurements of heat flux at the ocean surface - are first outlined. The limits of heave and roll motion compatible with the desired measurement accuracy are then established. Given the stochastic nature of platform response, these limits are stipulated in terms of expected means. A review is then made, in some detail, of the analytical approach followed and of the computer programs used to compute the statistical expectations of buoy heave and roll response to random sea excitation. The next section of the report describes the comprehensive parametric study performed on some twenty different buoy configurations. The purpose of this study was first to investigate the dynamic response of a plausible base line design and of modified versions of the base line. A comparison of the dynamic response of these configurations could then"be made, and the good features that this comparison would reveal could be used to design the buoy prototype. Following this approach a final configuration was specified which would meet the rather severe motion requirements (0. 2 feet RMS in heave and 5. 0 degrees RMS in roll in sea state 3). The final section describes the techniques recommended to deploy and recover the 60 feet long buoy prototype.