A theoretical scaling was made in order to acquire the ice resistance of ships in level ice. Ice resistance of ice-breaker Ermak was calculated by Kashteljan eequation and it's model test results were compared with full-scale measurements. Atkins's ice number and Norman Jones's dimensionless numbers were investigated and discussed.

Hull roughness due to corrosions of outer hull and had applications on outer hull paints was analyzed theoretically. It's value which was gainable practically, was studied, and estimated power penalty formular correspon-ding to that value were reviewed. Local roughness penalty and roughness texture penalty that paint manahers in ship yard can easily were compared and studied by dotting actual ships in the issued curves. Losses and benifits of hull roughness & the specification choise of A/F paint which managers of ship maintenance were much interested in have been calculated through actual ships. The paper is illustrating that how much the specification choise and managing of A/F paint have effects on fuel consumption of ship in program. It is urgently required that recent developed antifouling paints of new A/F generation should be adopted to new ship building by big shipping companies in view of the environmental protection and the economical maintenance of ships.

In connection to the design of high speed vessels, the numerical simulation is carried out to make clear the property of flows and breaking phenomena around the catamaran. It is because the bradking phenome-non is closely related to the free-surface turbulent flow. The free-surface wave and transverse velocity vectors are calculated around the twin and demi hull of the catamaran. Computed results are applied to detect the appearance of sub-breaking waves around the hull. The critical condition for their appearance is studied at two Froude numbers of 0.45 and 0.95. The nu-merical analysis shows that the breaking is more serious near the twin hull rather the demi hull. To simu-late the flows, the Navier-Stokes solver is invoked with a free-surface. The computation is made only in half a domain because it is symmetric in the shape.

ICLL 66 is the most widely ratified instrument of the IMO and is, along with the International Convention on Safety of life at Sea (SOLAS), the primary document setting forth internationally agreed ship safety standards. ICLL 66 set freeboard requirement based on experience gained from the first Load Line Convention in 1930 and on contemporary developments in ship design. Reexamination of ICLL 66 is indicated by the proliferation of novel ship designs for which it lacks adequate regulations and by significant advancements in analytical seakeeping and deck wetness prediction techniques now available to the designer. In this paper, the Freeboard Advisory Group reviews these issues against the changing climate of the marine industry and maritime administrations, discusses the state of the art in analytical seakeeping programs, and outlines a series of recommendations for the establishment of a new international load line convention for the next century. The steps needs for an international program at IMO are discussed and a new convention is proposed.

When the vessel is running at the very low Froude numbers, the free-surface is difficult to be disturbed, wave-making is negligible, and the double -model velocity potential gives a very good approximation for calculating the velocity distribution just outside the boundary layer. If the speed of incident flow is gradually increased, the most perceptible change is the rise of the flow surface at stem. With further increase in speed, the nature of the flow at the bow changes completely, The flow ahead of the bow becomes more distrubed, the rise at the stem to stagnation height disappear, and the first wave crest, of less than the stagnation height, appears a small distance downstream from the stem. The present study is concerned with a small region of this flow, mainly in the bow region. The present investigation is primarily an experimental study of the flow in the bow region of s ship model, and it is undertaken in order to investigated systematically, the effect of bow geometry on this flow. The long-range objective is to use these results to guide the development of a mathematical model for predicting the flow about a ship's bow.

선박설계의 과정에서의 설계변수가 건조된 선박의 운항경제성에 미치는 영향을 조사하였다. 대상선박은 산적화물선으로하였고, 전통적인 설계방식을 전산화하였고, 건조비는 국내의 대형조선소의 경우로 하였다. 경제성검토기준은 貨物運負率 (Required Freight Rate, Unit: U.S.D./Ton)를 사용하였다. 계산결과의 비교를 용이하게 하기위하여 션박의 주요치수는 무차원화하였다. 재화용량, 주요치수, 선형계수등이 운항비에 주는 영향으로 인하여 유가가 상승되면 속장비가 크고 속 력이 비교적 작은 선박이 경제적으로 우수한것으로 판단되었다. 이 프로그램은 조선소의 수주와 선주의 경영에도 많은 도움이 될것으로 생각된다.

The analysis and investigation are described for White's[2] equations compared to the equations of Runeburg[3] and Milano[5] for continuous icebreaking mode, Tunik[8-1] and Ghoneim[8-2] for ramming icebreaking mode. Calculation results compare reasonably well with published model-scale and full-scale icebreaker data by Baker[1] and Dick[11]. During continuous and ramming mode operation, using characteristics of an incebreaker, down ward force on ice and standard ice thickness broken are predicted. Additionally draft, trim and extraction difficulty are also predicted. The bow part line of an icebreakin gply vessel is designed aiming to maximize the ice breaking capabiltiy as following conditions-low bow angle[20 degrees] at designed waterline, small spread angle complement [6 degrees] at designed waterline, small spread angle complement [6 degrees] and high propeller thrust [220tons]. with plow, two reamers and wave type bumper.

The study presents the optimum design of B/C midship structure based on the classification society's Rule. The SUMT (Sequential Unconstrained Minimization Technique), using the Direct Search Methods (Hooke and Jeeves, Simplex) is applied to the solution of this nonlinear optimum design problem with constraints. Through the optimum designs of existing ships(60k, 186k, 220k), the amount 0.45-6.18% in weight of their midship structures are obtained on the viewpoint of minimum weight design.

This paper deals with the method of determining the drag of hull surface which has any quality of roughness. The method consists mainly of the theoretical point of view, then the theory enables the drag coefficient to be calculated at full scale. The hydrodynamical roughness function of hull surface △U+, affected by the hull roughness are considered as to two cases, smooth surface and rough surface case separately. The inadequacy of a single parameter to define hull roughness is discussed and thus an as additional texture parameter is proposed.

In spite of the widespread use of stiffend plates in ship structures, it is very difficult to analysis these directly. So, in conventional analysis of plate structures, above structures are used to be idealized as orthotropic plate or grillage structures. Lately, the development of large computers, it is able to apply the optimum techniques to structural design. In this paper, the double bottom structure of Bulk Carrier was idealized into flat grillage which is composed of intersecting beam stiffencers primarily loaded mormal to its surface. And strength analysis was carried out by using the finite element method based on displacement. And further, according to variation of floor space and double tobbon heightm, the optimum design was carrid out by using Hooke and Jeeves direct search method.

In this paper the dynamic effects due to the free water motions in tanks upon the lateral motion of a floating body in regular waves are calculated, in order to obtain the relationship between a motion of a floating body and that of the free water in tanks. Under the assumption that the fluid is ideal and motion amplitudes are small, velocity potential of the fluid in tanks is calculated by the source distribution method and the hydrodynamic forces and moments are calculated by the integration of fluid pressures over the tank surface. Hydrodynamic effects of the fluid on the floating body are expressed in terms of added mass and coupling coefficient obtained from the integration. Computations are carried out for ship with seven wide center tanks and comparisons between the liquid cargo loading case and the rigid cargo loading case are shown.

From time to time the light weight distribution has been discussed, It play an important part in the preliminary design state because of its influence on the available deadweight. Up to the past, the Light weight distribution acting on the ship has been estimated graphically by means of integraph or approximately by the simplified calculations. Recent development has made it possible to use Lloyd's coffin method or Robb's coffin method for Bulk Carrier, Tanker, Cargo ship where the hull weight is distributed based upon the CB The hull weight distribution is then super-composed by number of fixed weights(i.e. machinery , equipment, etc.) The authors built up the method by which the Light weight distribution is calculated using a computer. In the usual calculations, the higher accuracy is aimed at, the longer time would be taken, therefore the accuracy would not be so good as to be expected if the time is restricted. The method using a computer can dissolve these and calculated accurately in shorter time the Light weight distribution with less data.