• Journal of Ocean Engineering and Technology
• /
• v.19 no.6 s.67
• /
• pp.50-57
• /
• 2005

Ice resistance on ice-transiting vessels is one of th￡ important issues concerning th￡ design of ships with ice classes. In this study, th￡ development of GUI software for estimation of ice resistance on ice-transiting vessels is discussed. lee resistance estimation equations, based on model tests and full-scale sea trial data from many previous research articles, are studied in conjunction with two ship categories i.e., ,icebreakers/supply/tug vessels and ice-strengthened cargo vessels. lee resistance estimation equations are summarized in common format and are compared with each other. The GUI software 'Ice View,' written in MS Visual Basic language, can calculate ice resistances according to varying ice thickness and ship speed. The software can provide the calculated results, with suitable tables and graphs, for easy comparison of each ice resistance estimation equation.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.7 no.4
• /
• pp.699-707
• /
• 2015

The ice-resistance estimation technique for icebreaking ships had been studied intensively over recent years to meet the needs of designing Arctic vessels. Before testing in the ice model basin, the estimation of a ship's ice resistance with high reliability is very important to decide the delivered power necessary for level ice operation. The main idea of previous studies came from several empirical formulas, such as Poznyak and Ionov (1981), Enkvist (1972) and Shimansky (1938) methods, in which ice resistance components such as icebreaking, buoyancy and clearing resistances were represented by the integral equations along the Design Load Water Line (DLWL). The current study proposes a few modified methods not only considering the DLWL shape, but also the hull shape under the DLWL. In the proposed methodology, the DLWL shape for icebreaking resistance and the hull shape under the DLWL for buoyancy and clearing resistances can be directly considered in the calculation. Especially, when calculating clearing resistance, the flow pattern of ice particles under the DLWL of ship is assumed to be in accordance with the ice flow observed during ice model testing. This paper also deals with application examples for a few ship designs and its ice model testing programs at the AARC ice model basin. From the comparison of results of the model test and the estimation, the reliability of this estimation technique has been discussed.

• Journal of the Society of Naval Architects of Korea
• /
• v.43 no.2 s.146
• /
• pp.147-155
• /
• 2006

Ice resistance estimation equations based on model tests and full-scale sea trial data from many previous research articles are studied. Measured ice resistance data and its empirical/semi-empirical estimation equations are summarized in common format and are compared with each other, considering three ship categories, i.e, icebreakers, tug/supply vessels, ice-strengthened cargo vessels. The most suitable estimation methods or prediction equations are recommended based on this ice resistance data analysis.

• Journal of the Society of Naval Architects of Korea
• /
• v.55 no.4
• /
• pp.313-320
• /
• 2018

As ships operating on the Arctic route are exposed to various ice environments such as level ice, pre-swan, pack ice, ice ridge and brash ice, it is essential to estimate the ice resistance according to the ice environment. Methods for estimating the ice resistance include a method using mathematical model, numerical simulation, and a method using empirical formula. In this study, empirical formulas are used to estimate the ice resistance. The purpose of this study is to develop the ice resistance and attainable speed estimation program(I-RES) for brash ice. To develop the Brash ice attainable speed estimation algorithm, the environmental characteristics of the brash ice were analyzed, and the results of I-RES were evaluated by comparing the model test results of brash ice. The accuracy of I-RES for brash ice is around 20% in this study but it will be more developed near future with accumulating more model test results and calculation results.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.7 no.3
• /
• pp.626-639
• /
• 2015

Ice resistance is defined as the time average of all longitudinal forces due to ice acting on the ship. Estimation of ship's resistance in ice-covered waters is very important to both designers and shipbuilders since it is closely related to propulsion of a ship and it determines the engine power of the ship. Good ice performance requires ice resistance should be as low as possible to allow different manoeuvres. In this paper, different numerical methods are presented to calculate ice resistance, including semi-analytical method and empirical methods. A model test of an icebreaking vessel that was done in an ice basin has been introduced for going straight ahead in level ice at low speed. Then the comparison between model test results and numerical results are made. Some discussions and suggestions are presented as well to provide an insight into icebreaking vessel design at early stage.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.10 no.4
• /
• pp.491-498
• /
• 2018

The cost evaluation for voyage route planning in an ice-covered sea is one of the major topics among ship owners. Information of the ice properties, such as ice type, concentration of ice, ice thickness, strength of ice, and speed-power relation under ice conditions are important for determining the optimal route in ice and low operational cost perspective. To determine achievable speed at any designated pack ice condition, a model test of resistance, self-propulsion, and overload test in ice and ice-free water were carried out in a KRISO ice tank and towing tank. The available net thrust for ice and an estimation of the ice resistance under any pack ice condition were also performed by I-RES. The in-house code called 'I-RES', which is an ice resistance estimation tool that applies an empirical formula, was modified for the pack ice module in this study. Careful observations of underwater videos of the ice model test made it possible to understand the physical phenomena of underneath of the hull bottom surface and determine the coverage of buoyancy. The clearing resistance of ice can be calculated by subtracting the buoyance and open water resistance form the pre-sawn ice resistance. The model test results in pack ice were compared with the calculation results to obtain a correlation factor among the pack ice resistance, ice concentration, and ship speed. The resulting correlation factors were applied to the calculation results to determine the pack ice resistance under any pack ice condition. The pack ice resistance under the arbitrary pack ice condition could be estimated because software I-RES could control all the ice properties. The available net thrust in ice, which is the over thrust that overcomes the pack ice resistance, will change the speed of a ship according to the bollard pull test results and thruster characteristics (engine & propulsion combination). The attainable speed at a certain ice concentration of pack ice was determined using the interpolation method. This paper reports a procedure to determine the attainable speed in pack ice and the sample calculation using the Araon vessel was performed to confirm the entire process. A more detailed description of the determination of the attainable speed is described. The attainable speed in 1.0 m, 90% pack ice and 540 kPa strength was 13.3 knots.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2018.11a
• /
• pp.177-180
• /
• 2018

As ships operating on the Arctic route are exposed to various ice environments such as level ice, pre-swan, pack ice, ice ridge and brash ice, it is essential to estimate the ice resistance according to the ice environment. Methods for estimating the ice resistance include a method using mathematical model, numerical simulation, and a method using empirical formula. In this study, empirical formulas are used to estimate the ice resistance. The purpose of this study is to develop the ice resistance and attainable speed estimation program(I-RES) for various ice environments.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.8 no.3
• /
• pp.228-234
• /
• 2016

Recent icebreaking ships need to be designed to enhance not only icebreaking capability but also turning ability. For the evaluation of ice resistance induced by an icebreaking hull form, HHI (Hyundai Heavy Industries) has developed the hybrid empirical formulas (Park et al., 2015) by considering the geometrical hull shape features, such as waterline and underwater sections. However, the empirical formulas have inherent limits to the precise estimation of the icebreaking and turning ability because the breaking process and the resulting pattern are ignored. For this reason, numerical calculation in time domain is performed to predict the icebreaking process and pattern. In the simulation, varying crushing stress according to velocity vectors and contact areas between hull and ice is newly introduced. Moreover, the simulation results were verified by comparing them with the model test results for three different bow-first icebreaking models.

• Journal of the Society of Naval Architects of Korea
• /
• v.49 no.1
• /
• pp.45-51
• /
• 2012

Sea ice properties have been considered a key indicator in the structural design criteria of icebreaking vessels and arctic offshore platforms to estimate design ice load and resistance for their safety management in Arctic Ocean. A measurement study of sea ice properties was conducted during July to August of 2011 with the Korean icebreaking research vessel "Araon" around Chukchi Borderland. The sea ice concentration appears to be rapidly decreasing during this cruise. Ice condition seems to be thick second-year ice and multi-year ice and then, a lot of melt ponds were observed in the surface of ice floe. Calculated flexural strength of sea ice was about 250~550kPa, ice thickness was roughly 1.3~3.0m. In this research we performed field experiment to measure ice temperature along the depth, thickness, density, salinity, brine volume ratio and crystal structure. Apparent conductivities derived with the electromagnetic induction instrument were compared to drill hole measurement results and accuracy of sea ice thickness estimation formula was discussed.