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Plates and Stiffened Panels
Published in Ever J. Barbero, Introduction to Composite Materials Design, 2017
where p is the pressure in psi, v is the speed in m.p.h., Lw $ L_{w} $ is the waterline length in feet, D=144.55 $ D=144.55 $ is a constant involving the density of water and dimension conversion factors; A, B, C are empirical constants given in [274] as A=2.151 $ A=2.151 $ , B=1.267 $ B=1.267 $ , C=16.884 $ C=16.884 $ . For this example, the empirical formula yields p=0.1735 $ p=0.1735 $ MPa.
Research Vessel Construction—Terminology, Equipment, and Machinery
Published in George A. Maul, The Oceanographer's Companion, 2017
Figure 3.1 is a view from the starboard side of a proposed research vessel. The vessel particulars are molded length = 78 feet, waterline length = 73 feet, molded beam = 24 feet, and full load draft = 6 feet. The term “molded” refers to the maximum dimension, and molded beam (width) is usually measured amidships; a common term for molded length is length overall (LOA). Waterline length is horizontally measured from the intersection of the bow with the water to the stern, and draft is the vertical dimension from the waterline to the keel (the chief longitudinal structural member along the bottom from bow to stern). To scale, the person standing on the superstructure deck is 6 feet; he or she is standing on the fo'c'sle where the forecastle would be located on a fourteenth-century warship. The pilothouse, also called the bridge or sometimes the wheel house, is located just aft of the standing figure (see also Figure 3.4). On a larger ship, the bridge extends from port to starboard, houses all the navigation equipment, and may have bridge wings protruding out over the side for better visibility and navigation. The “roof” of the pilothouse is called the pilothouse deck, sometimes called the flying bridge.
An investigation into the effect of the Hull Vane on the ship resistance in OpenFOAM
Published in Petar Georgiev, C. Guedes Soares, Sustainable Development and Innovations in Marine Technologies, 2019
C. Celik, D.B. Danisman, P. Kaklis, S. Khan
The NACA4412 hydrofoil which is broadly used in the literature has been selected for the Hull Vane cross section. The initial chord (c) length of the Hull Vane is 2% of the waterline length (LWL = 3.47 m). Then the chord length of the Hull Vane has been changed by fixing the thickness of the Hull Vane. In CFD simulations, the leading edge of the Hull Vane has been fixed behind the transom of the ship model. Also, the attack angle has been kept at 0 degrees with respect to the calm waterline. The span length of the Hull Vane is equal to the ship model breadth. The Hull Vane configuration is shown in Figure 2. CFD simulations have been performed without the Hull Vane struts and the propellers of the ship model.
Numerical parametric assessment of the effects of stern wedges on the pressure and friction resistance of high-speed craft
Published in Ships and Offshore Structures, 2023
Parviz Ghadimi, Farzan Kiani Ilaghi, Mohammad Sheikholeslami
Broad ranges are considered when selecting wedge height and length levels, as well as the speed of the wedge-mounted hull. Hence, four levels of the wedge height, i.e. 3, 5, 7, and 10 mm, which correspond to 0.5 - 1.8% of the vessel beam, and two levels of wedge lengths, i.e. 92 and 184 mm corresponding to 16.7 - 33.4% of the vessel beam have been tested at Beam Froude numbers of 2.15, 3.01, and 4.30. As mentioned in section 1.2, it is suggested that the wedge height be within the boundary layer of the vessel aft to minimise resistance, which is met by the selected wedge height values. In the case of the wedge length, Cole and Millward (1973) and Millward (1976) suggested the wedge length to be in the range of 5–10% of the waterline length of the vessel at rest, and the selected values in the current paper are in the range of 4–8% of the waterline length at rest. To better understand the impact of the wedge effects, a parametric study is conducted at higher speeds, as the effect is less noticeable at lower speeds.
Analysis of surge added mass of planing hulls by model experiment
Published in Ships and Offshore Structures, 2020
Hamid Zeraatgar, Aliasghar Moghaddas, Kazem Sadati
Lewandowski (2004) approximated the longitudinal added mass of ship by concept of ‘equivalent spheroid' and extend of the Newman method for added mass evaluation of lateral motion, say surge motion. For ship hulls, he used the term of ‘equivalent spheroid'. Using the Lamb’s accession to inertia coefficient for surge motion, one may write:where is the SAM of ship, is the water density, is the displacement volume of ship and is the added mass coefficient. The added mass coefficient is a function of the eccentricity of the revolutionary ellipsoid, e, only:where a and b are the major and minor radius of spheroid, respectively. Assuming ship underwater hull is a body of revolution, ship dimensions equivalent to spheroid are replaced as follows (see Figure 10):where d and L are the maximum diameter and waterline length of a ship as follows:
A simplified approach for voyage analysis of fouled hull in a tropical marine environment
Published in Ships and Offshore Structures, 2021
Della Thomas, S. Surendran, Nilesh J. Vasa
The resistance of the bare hull is determined in the towing tank and skin friction for roughness is determined using Townsin formulae (Townsin 2003). To simulate the effect of the various biofouling growth stages, the ΔCF or correlation allowance factor (also denoted by CA) was varied. Hence, the viscous resistance co-efficient has to be added with ‘roughness allowance’ or the correlation allowance as per Equation (9) below. Here ks – average amplitude of roughness of the wetted surface of the ship, the typical value for the hull roughness is 150*10−6. L – waterline length of the hull in m.