1,720,978 research outputs found
Turning a length of oil absorbent: A numerical simulation
No full textMechanical, Maritime and Materials EngineeringMarine and Transport TechnologyShip Hydromechanics and Structures5045
Nonlinear Behaviour of Fast Monohulls in Head Waves
No full textMechanical Maritime and Materials Engineerin
Vessel with improved motion control
No full textThe invention concerns a vessel (1) having a planing surface (2) and a transom (3) at a stern of the vessel, mounted on the transom is an interceptor (4) and an actuator (7) to move the interceptor in vertical direction. In accordance with the invention the transom (3) defines a sharp edge with the planing surface and the underside of the interceptor comprises a convex rounded edge (5) extending upwards to the rear with a leading edge (6) of the convex rounded edge having a tangent approximately parallel to the water flow along the planing surface (2) near the transom (3), and/or the transom (3) defines a convex rounded edge (5) with the planing surface with a leading edge (6) of the convex rounded edge being tangent to the planing surface (2) and the interceptor (4) defines at its lowest part a sharp edge that can move behind the convex rounded edge in vertical direction.Marine and Transport TechnologyMechanical, Maritime and Materials Engineerin
Vessel with system for transferring persons or goods
No full textThe invention concerns a vessel (l) comprising a transfer system for transferring persons or goods from the vessel while subjected to waves and/or swell towards a substantially stationary destination, wherein the transfer system comprises a platform (2) having a first mass for supporting the persons or goods during transfer, and platform actuators (3) connecting the platform to the vessel and adapted for moving the platform relative to the vessel in such a manner that the platform or part of the platform is maintained spatially in a substantially stationary position.Marine and Transport TechnologyMechanical, Maritime and Materials Engineerin
The Aero-Hydrodynamic Characteristics of Yachts Sailing Upwind in Waves
No full textA common practice during the design of a sailing yacht is to assume an ideal environment. The wind is constant in intensity and direction and the sea is calm. In this situation, an equilibrium between the aerodynamic and hydrodynamic forces and moments can be found. The equations of equilibrium are thus solved to find the best setup (combination of sails, sail trim, etc.) in order to achieve the maximum boat speed. This procedure is the core of a 'traditional' Velocity Prediction Program (VPP), which was first introduced in 1976. Since then many improvements have been made and nowadays VPPs are capable of dealing with the most diverse designs. However, in nearly forty years of life, the nature of these programs has not changed and, still, important dynamic effects caused by the real environment, are not taken into account. Investigating the performance of a yacht taking into account these effects, is far from easy. Indeed, the equations of equilibrium should be replaced by the more complicated equations of motion which need to be solved in the time domain. However, in recent years, the dynamic characteristics of a yacht sailing in waves and shifting winds (real environment) have become a more popular topic in the sailing yacht community. In the wake of the increasing interest towards this subject, the present work aims to investigate some important dynamic aspects. The effect of the surge motion and of the heeling angle on the motions of heave and pitch, and on the mean added resistance, are studied by means of towing-tank tests. These are performed on two models of series 4 of the Delft Systematic Yacht Hull Series. Then, time-domain simulations are performed to study the effect of a pitch-induced oscillating aerodynamic force on the seakeeping of yachts sailing upwind in waves. The aerodynamic force is calculated using a quasi-steady as well as an unsteady method, whereas the hydrodynamic part of the problem is tackled using a strip-theory program which is capable of considering asymmetric hull shapes (e.g. hulls with a heeling angle). The results show that surge has a small influence on the motions and on the mean added resistance alike. The heeling angle on the other hand, prove to have a large effect on the seakeeping of the models. This effect can be qualitatively predicted by the strip-theory program, although the trend is not always correct. Finally, in same cases, the aerodynamic force significantly affects the pitch and heave motions and this results in a considerable reduction of the added resistance in waves.Ship Hydromechanics and StructuresMaritime and Transport TechnologyMechanical, Maritime and Materials Engineerin
Fast ship
No full textThe invention concerns a ship whereby the hull and the mechanical propulsion device are designed such that the Froude number is larger than 0.5. In the aft ship the hull has a bottom with V-shaped bottom surfaces with a deadrise angle that is less than 40 degrees and the hull has substantially vertical sides. In the hull are a passenger compartment and a trim tank. The trim tank volume is such that the weight of a filled trim tank is more than 30 % of the weight of displacement of the hull with an empty trim tank, filling the trim tank with water increases the amidships immersed width with at least 10%, and the bottom surfaces (15) have bilge keels (13,26) fully immersed when the trim tank is filled with water and the bilge keels are at least in part above the water level when the trim tank is empty.Marine and Transport TechnologyMechanical, Maritime and Materials Engineerin
Investigation of Nonlinearities in the Superposition of Ship Motions by 6DOF Forced Oscillations
No full textMarine and Transport TechnologyMechanical, Maritime and Materials Engineerin
Modelling operator behaviour: An experimental approach to model operator behaviour on board fast RIBs
No full textThe main aim of this thesis is to develop an operator behaviour model on board fast RIBs.Marine and Transport TechnologyMechanical, Maritime and Materials Engineerin
The results of the Delft Systematic Deadrise Series
No full textIn the present paper the development of the Delft Systematic Deadrise Series (DSDS) is described. The DSDS has been under development for decades by now and consists of a large family of systematically varied hard chine planing monohulls, based on the original research by Clement and Blount, which have all been tested in the same speed range, changing the same parameters and using the same experimental set up. The rationale behind the DSDS is highlighted. The DSDS contains up to now some 24 different models in 350 different conditions all tested in the same speed range between Fn∇ = 0.75 and Fn∇ = 3.0. Recently there has been a new extension to the DSDS with the inclusion of more measurements on hulls with twisted bottom and rocker in the aft ship. These results are presented in this paper.In addition detailed access is facilitated to all the hull geometries used into the DSDS and to all the raw measurement data obtained during the tests by means of free access to a dedicated website.Ship Hydromechanics and Structure
Ship
No full textThe invention concerns a ship designed for use at high speed and heavy seas having a single long and slender hull with a narrow beam and a more or less vertical bow, whereby the front half of the hull has more or less vertical sides, minimal flare in the bow sections and towards the bow an increase in draught at its center line combined with a more or less similar increase of freeboard and whereby the aft end of the hull has a flat or slightly V-shaped bottom with one or more propellers and/or waterjets as propulsion means. In accordance with the invention the bow has a fillet radius of at least 1 % of the beam.Mechanical, Maritime and Materials Engineerin
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