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Prismatic Coefficient

What Hull Shape Is Best?

Back at the dawn of maritime history, a coastal dweller first took a log and ventured out on the water. Over time his craft evolved from a rough log to one that had shape at the ends and was hollowed out. These changes to the basic log shape were the first example of modifying a hull form to increase carrying capacity, improve ride comfort, and to reduce resistance. Since then, shipbuilders, naval architects, and ship owners have experimented with hull shapes and the number of hulls to find the "best" design. Let's look at some of those variations to understand the challenges of choosing a hull shape. Monohull Design The basic monohull can be defined by six key numbers: length, beam, depth of hull at midships, design draft, prismatic coefficient, and displacement. Length, beam, and draft are familiar to everyone. Depth of hull at midships gives an idea of the freeboard as well as an indication of the hull strength in bending. The prismatic coefficient is a measure of how much shape there is in the ends of a hull. A high prismatic coefficient means that the ends are full such as a tanker bow. A low prismatic means that the ends are fine, with little volume, such as a tugboat stern. The choice of what dimensions to use depends on the intended use of the vessel. For a passenger vessel, there are considerations of carrying capacity, operating environment, and type of operation

BMT’s Fleet Management System to Debut at Nor-Shipping


BMT SMART Ltd., the specialist fleet and vessel performance management company of BMT Group, will launch its new SMARTFLEET Management system at Nor-Shipping in Oslo next month. Technical experts will be on hand to showcase the system and its capabilities whilst discussing with delegates their specific challenges and needs.    Peter Mantel, Managing Director of BMT SMART commented, “Whilst there are cost savings to be made through on-board optimization

Safety: Slip and Fall Accidents in the Marine Environment

Because the exposure to the marine environment and motions of a vessel, slips and falls are a significant source of personal injuries in floating equipment, probably substantially greater than most industry groups. Although there are a good number of publications, books and articles written regarding the subject of slip and falls, there are almost none addressing the conditions found in a marine environment, which influence slips and falls. Consensus

RoPax Propulsion Concept Proves Efficient

Wärtsilä, in conjunction with the Finnish research project SEATECH 2000+, has been developing some new machinery solutions for RoPax vessels. A promising concept is a semi-diesel electric machinery, where mechanical propulsion is combined with a diesel electric power plant. This new RoPax concept was presented for the first time at the Europort 2001 exhibition. The RoPax vessel has a semi-diesel electric machinery featuring a diesel mechanical part driving a conventional CP propeller and a

MHI LNG-FPSO Approval for Two Tank Types

Mitsubishi Heavy Industries, Ltd. (MHI) completed development related to floating production, storage and offloading units for liquefied natural gas (LNG-FPSO), and has obtained two kinds of approval in principle (AIP) from major international ship classification societies. In tandem with intensified activity in medium- and small-scale offshore gas field development, demand for LNG-FPSOs, a new method of gas production offering movable capability, has been increasing globally

NASSCO Licenses LNG Containment Tech to Braemar

Image: Braemar

General Dynamics NASSCO and Braemar LNG BV announce LNG containment technology licensing agreement   General Dynamics NASSCO and Braemar LNG BV, a wholly owned subsidiary of Braemar Shipping Services PLC, have signed a technology licensing agreement for Braemar to use NASSCO’s intellectual property in its design and construction of Flat-Panel, Semi-Membrane, Prismatic-Shaped (FSP) LNG containment systems.   

DSME's New LNG Tank Technology Approved by LR

ACTIB ((Aluminium Cargo Tank Independent Type B) tanks - prismatic, large, independent cargo tanks -  reduce sloshing, suitable for LNG containment The ACTIB tanks, constructed of insulated aluminium 5083, will have the world’s largest storage capacity in an independent, insulated LNG tank system. The volume capacity in the initial design will be nearly three times larger than comparable types currently in operation.

MOL Ink Deal to Build, Charter 300m LNG Carrier

New LNG carrier rendering courtesy of MOL

Mitsui O.S.K. Lines (MOL) inform it has signed a Head of Agreement on joint ownership and 20-year charter contract for a newbuilding LNG carrier with Tokyo LNG Tanker Co., Ltd. At the same time, MOL signed a contract with Japan Marine United Corporation to build the new vessel. The ship is slated for completion in 2017. MOL will manage the new carrier, which will transport LNG mainly from the Cove Point LNG Project in the United States to Tokyo Gas facilities.

FSP LNG Containment System Construction To Begin Soon

Chairman Zhang Mi

  The joint venture group FSP LNG BV stated that it is taking the FSP LNG Flat Panel Semi-membrane Prismatic Type B containment system through General Design Approval (GDA) with the American Bureau of Shipping in Houston, and is projecting that construction of the first tank will begin at the end of this year.   Formed earlier this year to take the FSP LNG containment system through the general approval process, the group comprises Braemar Engineering

Altair's LNG Containment Concept Earns AIP from ABS

Classification society ABS has granted Approval in Principle (AIP) to Troy, Mich., based Altair for the Cubic Donut Tank System (CDTS) LNG containment concept. The CDTS concept is adapted from a patent first filed nearly 40 years ago. The principle behind the initial design concept is the construction of a near prismatic shape using 12 interconnected cylinders to create the structural efficiency of a spherical tank and the volumetric efficiency of a membrane tank.

MHI Debuts Non-ozone-depleting Refrigerant


  Mitsubishi Heavy Industries, Ltd. (MHI) has developed a new series of centrifugal chillers, dubbed the "ETI-Z Series," adopting a new refrigerant, HFO-1233zd(E), that offers outstanding environmental compatibility. The various models in the new series will be progressively

Bal Seal Adds Low-friction Seals Test Service

Photo: Bal Seal

Test service enhances Bal Seal offering for low-friction seals, verifies friction and leak rate for seals up to 22 in. diameter   A new test service introduced by Bal Seal Engineering, Inc. offers verified performance results for Bal Seal low-friction spring-energized seals used in

Foreship: New CFD Methodology

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In the quest to model real conditions faced by ships at sea for design purposes, earlier this summer Foreship unveiled details of a live project that has factored real sea states into CFD-based hull form optimization. The company reports that the results of ‘in wave’ analysis had

Hard Problems Demand Soft(ware) Solutions


Make no mistake, the commercial maritime industry will always revolve around heavy duty machinery and mega-machines designed to weather some of the toughest operating conditions on earth. But in recent years a proliferation of Software Solutions has evolved to help the machines operate more

Hydrodynamic Software Suites

Making design concept evaluation more efficient To support designers and engineers in evaluating design concepts more efficiently, MARIN has developed the hydrodynamic suites QSHIP and QPROP. Hydrodynamic considerations have a great impact on the operational performance of a ship during its

ClassNK Amends Steel Ships Survey, Construction Rules

Classification society ClassNK announced today that it has released an updated edition of the Rules and Guidance for the Survey and Construction of Steel Ships. ClassNK continuously reviews, updates, and amends its technical rules and guidance as part of its ongoing efforts to improve the

IHI Wins Order From Chinese Wison Group

IHI Floating Vessel Similar to FSRU

  IHI Corporation (IHI) received an order for two “IHI-SPB” LNG tanks to be installed in the Floating LNG Storage & Regasification Unit (FSRU) from Wison Group of Shanghai, China (Wison) who is known as the largest private EPC contractor in China

Seaborne Ethane and Demand for a New Ship Type

Inside a moss tank (Photo courtesy of LR)

Lloyd's Register report looks at the commercial landscape, regulatory issues and technical realities of a new trade in ethane emerging as a result of increased U.S. gas production - and the technology required for large ethane carriers U.S

PPG Offers SIGMASHIELD 1200 Coating for Shipping

SIGMASHIELD 1200 coating for shipping in harsh environments -

  PPG Industries' protective and marine coatings business is fulfilling growing demand for "ice class" marine coatings for hull protection with SIGMASHIELD® 1200 coating. Developed from research conducted in PPG’s own facilities

MN 100: Thordon Bearings Inc.


3225 Mainway Burlington, State ON Canada L9C5J8 Tel: (905) 335-1440   Email:  Website: President & CEO: Terry McGowan The Company: Thordon Bearings Inc. designs and manufactures a complete range of polymer bearing

New Options for Aerodynamic Analysis of Offshore Structures

Air flow around crane truss

Naval architecture and engineering firm Alan C. McClure Associates (ACMA) has recently completed a wind flow analysis on an offshore structure using its Computational Fluid Dynamics (CFD) software package. Until recently, no alternatives existed to determine the effect of aerodynamics and its

Great Ships of 2014: Gas Star - 84,000 CBM LPG Carrier

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Gas Star is the first of two 84,000 CBM LPG Carrier built by Hyundai Heavy Industries for KSS. The vessel measures 225 x 36.6 m, with a depth of 22.2 m and a design draft of 11.6 m.  The ship is powered by a HYUNDAI-MAN B&W 6S60MC-C8.2 main engine with a NCR output of 11,340 kW at 89

Braemar Sub-Licenses FSP Containment System

Braemar LNG BV, the wholly owned subsidiary of Braemar Shipping Services PLC, has issued a sub-license to FSP LNG BV for the design and construction of a new Flat-panel, Semi-membrane, Prismatic-shaped (FSP) containment system, under the terms of the license it holds with General Dynamics NASSCO

Gazprom Building up Resource Base

Geological exploration in Krasnoyarsk Territory

In 2014 Gazprom Group (excluding Gazprom Neft) performed exploratory drilling of above 125,000 m of rocks, constructed 32 prospecting and exploratory (7 and 25 accordingly) wells. Over six thousand linear kilometers of 2D seismic profiles were processed

BOURBON Installs Submarine Cable for Sabella D10 Project


BOURBON is participating in a tidal turbine connection project off the island of Ushant (Brittany, France), a first in France. A pioneer in the towing and installation of the first floating wind turbine off the coast of Portugal, BOURBON is committed in the field of renewable energies and is now

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