• 한국기계연구소 소보
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• s.17
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• pp.145-156
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• 1987

A PSWATH is a computer program for the determination of principal particulars of Small Waterplane Area Twin Hull (SWATH) Ship design at the preliminary design stage. This paper describes the PSWATH system and the underlying theory. The major calculation modules are hull definition, resistance and propulsion, weight estimation and pitch stability analysis. Use of the model is illustrated by input, output and means of examples.

• The Journal of Korea Robotics Society
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• v.11 no.4
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• pp.217-225
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• 2016

Dynamic Positioning (DP) is used to automatically maintain the position and heading of a floating structure subjected to environmental disturbances. A DP control system is composed of a motion controller to compute the desired force and moment and a thrust allocator to distribute the computed force and moment to multiple thrusters considering mechanical and operational constraints. Among various thruster configurations, azimuth thrusters or propeller/rudder pairs tend to make the allocation problem difficult to solve, because these types of propulsion systems include nonlinear constraints. In this paper, a dynamic positioning strategy for a twin-thruster ship that is propelled by two azimuthing thrusters is addressed, and a thrust allocation method which does not require a numerical optimization solver is proposed. The applicability of the proposed method is demonstrated with an experiment using an autonomous boat.

• Journal of Ocean Engineering and Technology
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• v.18 no.5
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• pp.57-63
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• 2004

Various propulsion systems, applicable for a G/T 47,000 class mid-size cruise ship, are discussed and a comparative study on stern forms and hull resistance characteristics is carried out, in relation to these propulsion systems. Based on shipyard production logs on similar cruise ships, a reference hull form of a single shaft propulsion system with center-skeg, is generated. Then two new stern hull forms are derived by using a hull transform technique: consisting of one stern form using a twin-skeg system and the other using the Azipod system. Using a CFD-based commercial flaw analysis program, WAVIS (WAve and VIScous flaw analysis system for hull form development), various hydrodynamic characteristics, including wave profiles and ship hull resistance, are compared for three hull forms.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.6
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• pp.491-497
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• 2012

A hull-form for a 32,000G/T class Ro-Pax ferry has developed in accordance with a need of ferry operators to reduce fuel oil consumption(FOC) due to the drastic increase in oil prices recently and strengthening of environmental rules and regulations such as CO2 emission. A twin-skeg type is applied as the hull-form in lieu of an open-shaft type in order to improve propulsion performance. In order to achieve this object, flow control devices are installed to reduce a propeller induced vibration which is a main reason to obstruct the application of twin-skeg type passenger vessels owing to an uncomfortable vibration level. Numerical simulation by using an in-house code and a commercial code (Fluent) has performed to find out an optimum design of the flow control devices and to check an improvement in cavity volume. Model tests in Samsung Ship Model Basin are carried out to evaluate propulsion performance with the developed twin-skeg type hull and a reference hull of open-shaft type. In conclusion, it is shown that the twin-skeg type hull is better than the open-shaft in FOC by around 7% and in cavity volume by 20% as well.

• Bulletin of the Society of Naval Architects of Korea
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• v.24 no.4
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• pp.71-83
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• 1987

There is at present a growing interest in the use of SWATH(Small Waterplane Area Twin Hull )ship for a variety of purposes due to their good seakeeping characteristics, small speed reduction in wave, and large deck area. Highly sophisticated design technology is requested to develop the SWATH ship. This paper describes the design technology for high speed coastal passenger SWATH ship which includes feasibility study, general arrangement and hull form design, resistance and propulsion test, motion test in regular waves, control fin design, and structural design.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.3
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• pp.196-204
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• 2018

Present paper shows the basic design procedure for platform support vessel operating in open sea, and hull form development process. General design concept considering the operating mission, operating sea condition and shipping freight, etc. is explained shortly. For the hull form design, the initial hull form was designed based on the reference PSVs. The resistance and propulsion test results for the initial hull form with twin Azimuth thruster were analyzed and a few items for improvement were derived. At the next stage, main parameters including Length, Cp-curve, Cb, Lcb, etc. were changed totally for the hull form improvement. Furthermore, 3 different bulbous bows for the fore-body design to reduce the wave resistance and after-body design to reduce the residual resistance were carried out. The best hull form among the 3 fore-bodies with same after-body was selected through the comparison of wave resistance calculation results. Twin ducted Azimuth thruster with the smaller propeller diameter than the former were adapted to increase the propulsive efficiency. The final hull form with the twin Azimuth thruster was evaluated to satisfy more than the target design speed 14 knots in sea condition with sea margin 15% at the 5,000kW BHP through the model test in KRISO.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.3
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• pp.466-477
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• 2015

In this study, a numerical prediction method on manoeuvrability of Wind Turbine Installation Vessel (WTIV) is presented. Planar Motion Mechanism (PMM) captive test for the bare hull of WTIV is carried out in the model basin and compared with the numerical results using RANS simulation based on Open-source Field Operation And Manipulation (OpenFOAM) calculation to validate the developed method. The manoeuvrability of WTIV with skeg and/or without skeg is investigated using the numerical approach along with the captive model test. In the numerical calculations, the dynamic stability index which indicates the course keeping ability is evaluated and compared for three different hull configurations i.e. bare hull and other two hulls with center skeg and twin skeg. This paper proves that the numerical approach using RANS simulation can be readily applied to estimate the manoeuvrability of WTIV at the initial design stage.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.2
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• pp.109-116
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• 2019

This paper carried out numerical analysis for estimating the propulsion performance of the model scale ONRT benchmark model of'Tokyo 2015 a workshop on CFD'. The method reflecting the scale effect of ITTC'78 method and form factor were used to compare the estimates of the effective wake ratio of full-scale. The numerical calculation was performed with Siemens's Star-CCM+, compared with IIHR model tests and the numerical analysis results of other research institutes, showing good agreement. In the case of an open stern and twin skeg ship, the validity of the ITTC'78 method can be confirmed by assuming that the effective wake ratio estimated from the numerical analysis results of model scale is similar to the effective wake ratio of full-scale.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.2
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• pp.20-34
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• 2003

The good sea-keeping capability of the SWATH(Small Waterplane Area Twin Hull) ship has been attractive for research or surveillance vessels. Especially, for the naval ships accomplishing the underwater acoustic missions, it is necessary to access and minimize the underwater radiated noise level generated by the ships. Therefore, acoustic signature management and control are very important topics for these vessels. Underwater radiation pattern in the low frequency range is dominated by the tonals from the vibration of onboard machinery. In this work, the radiated noise level generated by the propulsion machine in the submerged hull is predicted using the transfer function technique and the hull transfer function for the submerged hull is determined by analyzing the longitudinal/circumferential stiffened infinitely long cylindrical shell and considering the empirical database of the previous vessels. It is confirmed that the transfer function technique can give useful information for identifying the noise source and estimating its contribution to the total radiatied noise level.