고속 알루미늄 레저보트의 저항성능에 관한 연구

Abstract

In these days, by the influence of economic growth, five-days workweek system and of living conditions improvement, a leisure environment has been changed rapidly. Many people are demanding marine activity for leisure. By the effect of this increasing demand, various types of the boat are developing now.

In this study, a plan for designing the primary hull form has been provided based on the increasing demands of high speed leisure boats that can be worked in the coast, and the initial hull form of a 30 knots, 30-feet class leisure boat has been developed.

There are many different materials that can be used to build a boat. We can use Aluminum, Fiberglass Reinforced Plastic(FRP), Wooden planks and even Steel as an option to when building our boat. This study considers the main characteristics of aluminium alloys and fiberglass reinforced plastics in relation to the selection of the hull for high speed leisure boat.

Fiberglass over rigid foam is the material regularly used for boat building. The boats used FRP are more expensive than used to steel. However, the cost for maintenance is more economic. Therefore many shipbuilder preferred to build the boats used FRP in the past. Some disadvantages for FRP have become recently. Disadvantages of FRP are; Choice of vessel fixed once design is chosen and moulds made, Fire and health hazards from chemicals, Disposal of boat retired from service & Environmental pollution.

In the midst of the trend, it is demanded the material substituting for FRP. This study examined the aluminium as the material for high speed leisure boat. Aluminium alloys have the primary advantage of being light weight with some alloys having comparable strength to that of structural steel, thus providing better strength to weight ratio compared with steel. They also have high corrosion resistance. Advantages of aluminium alloys are: Light weight, Corrosion resistant, Easily formed, Easily fabricated, Readily available, Ductile, Non magnetic.

On the other hand, characteristics of the planing boat of a 30 ft class aluminium leisure boat were studied. Also the domestic and foreign research trend in the processes of hull form developing has been analyzed.

The fundamental performance of the developed hull form has been confirmed, the resistance performance were observed by the model test in high speed circulating water channel(CWC). Wave patterns are observed to make clear the relation between the resistance performance and the wave characteristics.

The effect of attached Side-Fin on the ship's side and trim tab under the ship's bottom have been analyzed in order to improve the resistance performance. These appendages effect on the resistance performance were also analyzed.

It is predicted that excessive running trim in high-speed area will affect the safety performance in waves. The Side-Fin can help the resistance performance. Especially it can raise the hull in the high-speed area. However if lift that acts at wings works at the back of center of buoyancy, the body of ship rises in stern and the phenomenon of squat occurs in bow. Hence decreased running trim can cause an increase in resistance. Accordingly it is required to determine the proper size and the position carefully.