Showing papers on "Transom published in 2021"

Optimization of the Propulsive Efficiency of a Fast Catamaran

Abstract: The present study deals with the local optimization of the stern area and of the propulsive efficiency of a battery-driven, fast catamaran vessel. The adopted approach considers a parametric model for the catamaran’s innovative transom stern and a QCM (Quasi-Continuous Method) body-force model for the effect of the fitted propellers. Hydrodynamic calculations were performed by the CFD code FreSCO+, which also enabled a deep analysis of the incurring unique propulsive phenomena. Numerical results of achieved high propulsive efficiency were verified by model experiments at the Hamburgische Schiffbau Versuchsanstalt (HSVA), proving the feasibility of the concept.

Effect of separation vortices on wave-induced sway force and yaw moment acting on a ship running in stern quartering waves

Abstract: For accurately evaluating the risk of broaching for a ship in stern quartering waves, the wave forces calculated with a slender body theory under the low encounter frequency assumption are often corrected empirically with the help of captive model experiment or computational fluid mechanics (CFD). However, the hydrodynamic explanation of such empirical correction was not sufficient so far. Thus, this paper attempts to provide an answer to this deficiency. First, we visualise the vortices shed from the hull surface using existing CFD results for the ONR tumblehome topside vessel. Then we extend Hamamoto’s slender body theory, in which the interaction between the shed vortex and the hull sections is taken into account for calm water, to the case in astern waves and apply it to the current case by using the CFD-based vortices strength and position. As a result, it is confirmed that additional hydrodynamic forces due to vortices shed from the hull surface other than transom are a major component of the empirical correction for supplementing the conventional slender body theory, which covers the Froude–Krylov force and hydrodynamic lift from the transom.

Reanalysis of the Sydney Harbor RiverCat Ferry

Abstract: In this paper, we revisit the hydrodynamics supporting the design and development of the RiverCat class of catamaran ferries operating in Sydney Harbor since 1991. More advanced software is used here. This software accounts for the hydrodynamics of the transom demisterns that experience partial or full ventilation, depending on the vessel speed. This ventilation gives rise to the hydrostatic drag, which adds to the total drag of the vessel. The presence of the transom also creates a hollow in the water. This hollow causes an effective hydrodynamic lengthening of the vessel, which leads to a reduction in the wave resistance. Hence, a detailed analysis is required in order to optimize the size of the transom. It is demonstrated that the drag of the vessel and the wave generation can be predicted with good accuracy. Finally, the software is also used to optimize the vessel further by means of affine transformations of the hull geometry.

Coastal part of bridge of mechanized complex

Abstract: FIELD: bridge engineering.SUBSTANCE: invention relates to the field of bridge-and-bridge devices, and more specifically to the coastal parts of the dismountable bridges. Coastal part of bridge of mechanized complex is made in the form of metal structure consisting of end bridge block, first dead-end, on which the bridge unit is installed, ramps attached by one end to the upper part of transom of the end block at the level of the carriageway, and by the other end laid on the second leg. Second leg is installed in the recess on the road flush with the roadway, and the angle of the ferrying equipment entrance to the ramp does not exceed 10 degrees. Besides, the ramps are laid on the bed with support planes made on the end part of each ramp. Besides, the ramps covering directly the track of the roadway have on both sides process ledges with width of not less than 8 cm and length measured from the end of the support plane of the ramp to its transom. At that, adjacent ramps have cutouts on corresponding side, into which ramps with technological projections are inserted and fixed with fixing pins.EFFECT: application of the declared technical solution will allow increasing average operating time for failure of the coastal part of the bridge of the mechanized complex, increasing throughput of the bridge.1 cl, 10 dwg

Vessel, in particular a yacht, with reduced transom draft

Abstract: The invention relates to a vessel (1), comprising a hull (2), with a forward portion (3), a central portion (4) and an aft portion (5), comprising a transom (6) and a propeller (7) arranged near the transom, the vessel during operation displaying a waterline (8), characterized in that a draft (9) at the transom, being a vertical distance between the lowermost position (10) of the transom and the waterline, is 0.1 - 0.7, preferably 0.2 - 0.5, more preferably around 0.4, times the draft (11) of the vessel, being a vertical distance between the waterline and the lowermost position (12) of the hull. Preferably, the hull has a hard-chine cross-section.

Apparatuses for supporting outboard motors with respect to marine vessels

Abstract: An apparatus is for supporting an outboard motor on a transom of a marine vessel. The apparatus has a transom bracket configured for fixed attachment to the transom; a supporting cradle that supports the outboard motor with respect to the transom bracket, wherein the supporting cradle is pivotable with respect to the transom bracket about a trim axis; and a trim actuator that is pivotally coupled to the transom bracket at a first trim actuator pivot axis and to the supporting cradle at a second trim actuator pivot axis. Extension of the trim actuator pivots the supporting cradle upwardly about the trim axis. Retraction of the trim actuator pivots the supporting cradle downwardly about the trim axis. The trim axis is located aftwardly of the first trim actuator pivot axis.

Vessel having mist shield for outboard engine

Abstract: A vessel, including a transom for mounting outboard engines thereto, is spanned on opposite sides by aft-facing hull extensions which extend beyond the engines and allow a swim platform to be positioned between the hull extensions. The design allows the outboard engines to be covered with an engine cover, which provides an attractive vessel design in which the outboard engines can be concealed with a cover, which may serve other functions, such as a seat or the like. The cover houses an engine cowl mist shield which includes a support frame surrounding one or more outboard engines. The frame includes aperture(s) with edges spaced from the cowl and a flexible member extending from the edges to the cowl below the air intake of the cowl, such that spray and mist from the operation of the vessel does not reach the air intake of the cowl.

Analysis of the skeleton tension structure as the load-bearing structure of a one-nave hall

Abstract: In designing cubature buildings, an important stage is the selection of an appropriate construction solution, depending on the intended use and location of the designed building. When selecting the load-bearing structures, the designers strive to ensure that the structure weighs as little as possible, while meeting the strength conditions and ensuring the safe operation of the building. The article compares the load-bearing systems of the steel structure of a one-nave hall due to the economy of execution and meeting the ULS and SLS conditions. The analysis was carried out on four types of transverse system, including three frame systems with tendons and for a frame system with a lattice transom of the “N” type. Static calculations as well as dimensioning and optimization of the transverse load-bearing structures were performed in RFEM program, modelling the hall structure in 3D.

Heavy Duty Transom for Structural Support Systems.

Abstract: This publication relates to a tubular transom in particular for temporary structures, such as scaffolding or false work and similar structure, having ends configured to be connected to verticals at node sections arranged at intervals on the verticals. Each end of the transom comprises a fastening device with an integrated profile part, releasably attached to the tubular transom in an opening at the ends of the tubular transom. The transom comprises a first and at least second elongate, parallel and hollow tube elements, interconnected at least at each end by intermediate integrated web plates, rigidly fixed to said at least two tube elements. A contact surface of the opening in the first tube, is transversally arranged relative to one or more web plates. A contact surface of the opening in the second tube is transversally arranged relative to one or more web plates. The opening at the ends of the transom having at least partly a complimentary shape.

Boat moving device

Abstract: FIELD: transportation.SUBSTANCE: invention relates to the movement of inflatable boats with a hinged transom on land. The boat moving device contains two stands, two wheels, two plates and tension springs. The plates are fixed symmetrically to transom. Pins are fixed on the plates. At the end of each rack, a through elongated hole is made in which the pin of the corresponding plate is hinged. Wheels are fixed on axles of the racks with possibility of rotation. One end of each tension spring is secured to a pin and the other to a corresponding post. The plates are in form of sectors and arc guides are made on them from the side of the arc surfaces. Each pin is fixed on the corresponding plate from the side of the central corner of the sector. The extreme positions of guides are made in form of L-shaped branches. Each rack contains a latch which is placed in an arc guide with ability to move and fix in extreme positions - lower (for land) and upper (for water).EFFECT: simplification of design of the device while maintaining dimensions of the boat in height after folding wheels.3 cl, 3 dwg

Semirigid inflatable boat with foldaway outboard motor

Abstract: An apparatus for moving an outboard motor installed on a watercraft of the type that comprises a transom for the stable coupling of adapted engagement elements that are jointly connected to the motor; the apparatus comprises a panel, which is articulated at least to bottom boards of the watercraft and at least partially superimposed on the transom, for the engagement of the engagement elements of the motor; the panel, by virtue of articulation elements, can move from a first configuration for navigation, in which it is partially superimposed on the transom and rigidly coupled thereto, to a second configuration for housing the watercraft, in which it is rotated substantially at right angles to the transom in the second configuration, the panel is almost parallel to a plane of the bottom boards of the watercraft.