Showing papers on "Beam (nautical) published in 1977"

Device for measuring the width of timber

Abstract: The width of a piece of timber, such as a board is measured with a device including a laser tube emitting laser beam to be reflected by a rotatable mirror polyhedron and a parabolic reflector into a direction along the board, mirror rasters being provided at intervals along the board so as to reflect laser beam pulses onto the board, each raster including a group of mirrors reflecting the beam pulses onto spots of the board that are spaced apart laterally across the board, and detecting means being provided for receiving the pulses reflected from the board surface in order to obtain information about the board width. Preferably, the pulses received by the detectors are transferred to a computer which calculates, in a manner known per se, the optimal sawing width for the board. Instead of the reflector, lens means may be used for directing the beam along the board.

Deep water berthing system for very large cargo carriers

Abstract: An off-shore berth for a ship, particularly a tanker, is described in which roll, pitch and yaw are neutralized. The ship is tautly attached to barges, one on either side, and a beam under the ship's keel is coupled to the barges. The beam is tethered to a permanent anchor in the sea floor.

Variation of parameters determining seakeeping

Abstract: The computer program TRIAL has been used to determine the seakeeping qualities in head waves of systematically varied ship forms. Nine variants of the Todd Series-60 model were developed having the same midship section coefficient, length/oblique beam ratio (L/B = 7) and length/draught ratio (L/T = 17.5). The ship form parameters which were varied were the block coefficient, the longitudinal position of the centre of buoyancy, and the forebody section shape. A ship length of 200 m was chosen as the "central length", since in fully developed seas, waves of this length contain the highest energy and attain the highest amplitude. An investigation of the influence of the weight distribution and variation of the sea condition has been carried out for this "central" value. The results show that pitching especially decreases with ship length, while heaving increases with speed. For V-shaped forebodies the heaving motion is strongly reduced, while there is an advantage in respect of added resistance up to a certain ship length, which depends on speed and sea-condition. Above this length, U-shaped sections are preferable.

Numerical solutions of transient three-dimensional ship-wave problems

Abstract: This paper presents a very efficient numerical technique for obtaining the transient three-dimensional flow about a ship with uniform speed in a channel from an abrupt start in calm water. The abrupt start is viewed as a very rapid acceleration from rest. Wigley hulls, characterized by small beam and draft-to-length ratios, have been used. Order from NSFI as No. 16652.

Pontoon type cargo vessel - has all cargo spaces above waterline and length to beam ratio of 4 to 1 for shallow draught

Abstract: The pontoon-type cargo vessel is conventional as regards propulsion and control but has its cargo space (5) entirely above the waterline (4) and a length: beam ratio of about 4:1. The spaces (7) for buoyancy and ballast, machinery and crew are below the waterline, with extensive watertight subdivision. For protection in the event of a collision the side compartments adjacent to the hull are all buoyancy/ballast ones. At one end of the vessel at least, vehicular access to the cargo space is provided for; access may also be possible through doors in the ship's side. The space may have longitudinal subdivisions (6), which may be portable, and may be covered. The wheelhouse may be retractable which, together with the vessel's draught due to its beam, allows it to use waters not normally accessible to vessels of its size.

Prediction of Ship Roll, Sway and Yaw Motions in Oblique Waves,

Abstract: : A theoretical model is developed for the prediction of ship lateral motions in oblique seas. The asymptotic behavior of this model in waves that are long relative to ship beam is examined, with particular emphasis on the classical problem of rolling in beam seas. The theoretical prediction of roll damping is discussed, and the importance of including dynamic lift on appendages is emphasized. Fairly extensive comparisons of predicted and measured roll response are made, with good agreement at all headings considered. (Author)

Computer aided ship hull definition at the naval ship engineering center

Abstract: The prototype CASDAC Hull Subsystem came into being in early 1976 and was first applied to the design of a 666 ft. l.b.p. cruiser. A primary objective of the system developers was to maximize, by their linked use, the short-term benefits from programs which had previously been developed under the auspices of the Computer Aided Ship Design and Construction (CASDAC) project. Four pre-existing programs make up the prototype system: 1. The Ship Hull Form Generator (HULGEN). 2. The Ship Hull Definition Program (HULDEF). 3. The Ship Hull Characteristics Program (SHCP). 4. The MIT Motions Program (MITM). HULGEN is an interactive graphics program to aid in the development of a ship's body plan. It is designed to provide, as nearly as possible, the same curves as those used in the manual hull development process. Given the dimensional parameters, length, beam, draught, prismatic and midship section coefficients, LCB and LCF, HULGEN develops the default parameters and control curves to produce a body plan. The key idea of HULDEF is the use of parametric cubic splines together with certain rules of interpolation to build up a line-for-line definition of the ship's hull which is sufficiently accurate for all ship design and construction purposes. Examples are given of the use of the two systems in the development of a variety of ships' body plans.

Operation unit used for ship building

Abstract: PURPOSE:To permit safe and efficient operation to be carried out by the provision of an operation unit, in which a plurality of slidable stages are supported for vertical movement on rails mounted on a beam member.