A wavelet for predicting the time-domain response of vertically tethered systems

The response wavelets for tether tension and the displacement of a package on the end of a tether rue derived from a linear, frequency-domain model of vertically tethered systems using inverse fourier transform techniques. Th ese wavelets are convolved with a record of ship displacement to predict th e instantaneous tension and displacement to an accuracy of better than 20% for a typical system. Although snap loads are non-linear and the response c annot be calculated while the tether is slack, the onset of zero tension - a precursor to snap loads is predicted by the wavelet, Thus, extreme and po tentially hazardous conditions are foreseeable with the wavelet and this in formation can be used in real-time to guide operations at sea. (C) 2000 Els evier Science Ltd. All rights reserved.