Showing papers in "Ocean Engineering in 1984"

TL;DR: In this paper, a four-parameter theoretical formulation was proposed to represent double-peaked spectra and was shown to provide an excellent fit to measured spectra, and the average values of the spectral parameters describing the two peaks did not show any clear dependence on significant wave height.

TL;DR: In this paper, a mathematical model describing the relative water motions inside a moonpool was developed, while also model tests were carried out to obtain empiric results with respect to the damping mechanisms and motion behaviour.

TL;DR: In this paper, the results of dynamic and steady-state cable simulations are used to show that a towed system can behave in either one or both ways on entering a turn, in a turn of small radius the system effectively collapses resulting in a large increase of fish depth and cable tension.

TL;DR: In this paper, an optical communications link and a radio frequency communications link are configured for oceanologic use so as to acquire engineering data in-water and to telemeter it to an associated shore station.

TL;DR: In this article, an efficient method of calculation for vertical, composite cylinders at finite depth is presented, and the results of this method are compared with numerical results obtained by a surface element method.

TL;DR: In this article, the wave forces acting on submerged circular cylinders moving forward with a constant velocity in regular waves are investigated experimentally, and the similarity and difference between them are discussed.

TL;DR: In this article, two-dimensional pre-elimination cable models are presented and assessed in relation to existing lumped mass and rod models, and it is shown that the rod model enjoys certain modeling and numerical advantages not shared by the lumped Mass model.

TL;DR: In this paper, the authors described the hydrodynamic forces and moments that act on a towed fish and related them to fundamental static and dynamic towing characteristics, and showed that decreasing the fin height almost to the point giving neutral stability in pitch, the fish maintains almost constant pitch attitude while being forced to heave or surge by ship motion transmitted down the cable.

TL;DR: In this paper, a general method for the dynamic analysis of multi-body offshore structures is presented, being based on a constraint matrix approach, which is applied to both the SBS and Yoke-CALM design of offshore mooring terminal.

TL;DR: In this paper, the effect of nonlinearities, such as wave-breaking and vertical asymmetry associated with sea waves, on the distribution of wave amplitudes is explored, and the construction of non-linear wave envelopes with the fast Fourier transform technique is described.

TL;DR: Supercritical planing hulls are very suitable for high speed ferries, patrol craft and crewboats as mentioned in this paper, and have been shown to be suitable for very high speed vessels.

TL;DR: In this paper, the extremal properties of the Morison equation F(t) were derived by means of a Slepian model for the behaviour of a circular pile around its local maxima.

TL;DR: In this article, the use of Hermite polynomial in the derivation of statistical properties of waves, wave field kinematics and dynamics and wave forces under various conditions is discussed.

TL;DR: In this paper, the authors examined the rolling motion of a ship with particular regard to the possibility of obtaining oscillations which are subharmonic to the excitation frequency, and three different mechanisms were found to be responsible for this phenomenon, the importance of which has already been recognized in the context of ship stability.

TL;DR: In this paper, the lateral motions of roll, yaw and sway of a heavy towed fish are investigated, and it is shown that very careful adjustment of fin size can reduce the amplitude of yawing motion by a factor of about 3.

TL;DR: In this paper, a comparison is made between extreme events in half-hour intervals of hurricane Camille wave data and events in synthesized Gaussian realizations having the same variance spectra as the measured data.

TL;DR: In this article, an analytical and experimental study on the transient response of semisubmersibles to bergybit impact and the strength of iceberg ice to high strain-rate loadings is presented.

TL;DR: In this article, the longitudinal shape of a flat plate's wake is estimated by using a methodology first suggested by Epshtein for flat plate wakes, and the result is in better agreement with experiment than previous formulations.

TL;DR: In this paper, a finite element method based on linear diffraction theory has been used to compute wave loads and moments about the bed of surface piercing cylinders of circular, square, rectangular and elliptical sections for different angles of wave incidence.

TL;DR: In this article, both the discrete contamination and fouling problems are exhibited, evidence is presented which identifies the source, and methods of minimizing their effects are examined; however, the authors do not identify the source of these problems.

TL;DR: In this paper, a hybrid marine vehicle based on a planing catamaran hull with two fully submerged hydrofoils mounted in tandem fore and aft is developed. And the hull form is developed by adding a high length/beam ratio, high dead-rise sidehull along the keel of each catamarans demihull.

TL;DR: In this paper, a new and simple method to determine the hydrodynamic coefficients for subsea pipelines in the drag and inertial flow regime is presented for three relative clearances of a pipeline model from the simulated ocean floor.

TL;DR: In this paper, a modified source-and-dipole type singularity panel method is proposed to calculate the flow properties for an oscillating arbitrary body in the presence of a free surface.

TL;DR: In this paper, three-dimensional cable profiles have been computed embodying experimentally determined values of all hydrodynamic quantities, and generalised data for estimation purposes plus examples of the variation with towing speed and scope of the tow-off angles and fish displacements to be expected of a typical towed system.

TL;DR: In this paper, an analysis of the dynamic load variations in the riser and yoke pivot components of an offshore vessel/mooring oil production and storage system was carried out in the frequency domain.

TL;DR: In this article, the main structural member of the boom, a triangular communications tower with rollers attached along its bottom side, is deployed horizontally from a long, flat deck such as a helicopter deck, and will support a 100-kg payload at its outboard end.

TL;DR: In this article, the optimal strength based on minimum cost objectives is obtained and illustrated by an example of a moveable platform which is to operate in an environment which includes moving ice depends on a number of ice dependent variables.

TL;DR: In this article, the probability density function for half-cycle excursions for an arbitrarily given wave spectrum is developed based on the Gaussian assumption and the results of numerical computations carried out using wave data obtained during hurricane Camille are presented.

TL;DR: In this paper, the authors deal with the analysis, synthesis and performance evaluation of the flow and dynamic characteristics of the new class of servo-controlled breathing regulators for underwater divers and develop rational design procedures and guides that would enable the regulator designers to select the optimal design parameters of this class of regulators.

TL;DR: In this article, the wave dispersion equation under ice is discussed and a set of coefficients synthesized using the properties of infinite series and Pade approximants are used for the calculation of wave characteristics in ice-covered sea.