نشریه مهندسی شناورهای تندرو
پیاپی 44 (بهار و تابستان 1393)

The high speed craft industry has largely been neglected in our country and dosent have an important role in the production, purchasing, sale, etc. of the marine industry, while the volume of transactions of this industry in other countries, indicates a good potential for it. One of the countries that the developing process of the high speed craft is well planned is Turkey, showing clearly results in the economy field. Due to the geographic proximity and cultural similarity of our country to Turkey, herein, the status of this industry in Turkey is discussed. In this paper, a general survey of the world economy of this industry is presented firstly. Then, the industry in India is reviewed including the growth of the industry, the market situation, consumption pattern of high speed boat, the presence of foreign countries, government regulations and the strengths, weaknesses and potential of the marketplace. Afterward, the effective factors of this industry development in Turkey such as; surrounding on three sides by the sea, Providing the necessary facilities, such as the construction of docks and harbors and access to services (maintenance, fuel, ...) are peresented. Finally, the benefits of the development of the high speed craft industry in the North Regions such as; Environmental Protection, job creation and economic growth of shipbuilding and marine industry are mentioned. In the southern coast, in addition to these benefits, the depersonalization is also achievable. It seems that by removing obstacles to private ownership of pleasure boat parking in coastal, the conditions for the growth of this industry are provided automaticly because of economically attractive. It is hoped that this will happen by the authorities and the private sector activity.

Interference flow field and surface waves generated by the semi-hulls motion of planning Catamaran, has significant effect on resistance, bottom pressure distribution of the body and loss of energy. Asymmetric planning semi-hulls surfaces generate more than dynamic lift than dead rise hull at the same condition. In this paper, flow around asymmetric planning catamaran semi-hulls in 3D state and two phases by using CFD simulated. Interference effect analysis is carry out by experimental data. In continuance, for interference and surface waves effects, modeling in single and dual semi-hulls state are simulated. For interference effect between asymmetric planning catamaran semi-hulls model test is conducted at the 5 varying tunnel spacing at same conditions. For investigate of lift coefficient and surface waves effects model test is conducted at 18 and 25 dead rise angle and various of trims. For investigate of surface waves sample around asymmetric planning catamaran demi-hulls and interference between, hydrodynamic analysis is carry out for dead rise angle 25 and trim angle 6. There is excellent overall agreement between measured, predicated and numerical lift coefficient over the rang of dead rise angle 18 and 25, speed coefficient 2.8 and 5, various of trim angle for asymmetric planning catamaran demi-hulls.

Influential factor in the maintenance of defense systems, navigation equipment, navigation aids and provide an ideal environment for increased power and efficiency of the staff, the right choice is an air conditioning system in Extremist vessels. This paper describes the types of HVAC systems on vessels Extremist with its advantages and disadvantages are reviewed. Finally, according to the model, length, volume and area of the room and floating cabins and other parameters of the software is the safest method, the capacity of 30 thousand t U per hour was obtained by selecting the capacity air conditioning system Floating were studied. In this method, 10 to 15% as a safety factor to the calculated cooling load is added. The results compared with the previous system can be used to optimize the HVAC system afloat and boost the country's defense can be used.

The main function of transmission system is to convert output rotary force of main engine into trust required for moving the vessel. Shaft is one of the elements of main transmission system which is composed of several sections. Shaft is influenced by pressure, bending and spiral loads. Therefore, the position of bearings and shaft designing are the major factors which reduce vibration and prevent resonance. In this paper, with various tests on two samples having the same diameter and different length, the position of bearings were studied. In accordance with the modes generated, we specified the position of bearings, so as the shaft receives less vibration. In this regard, early and precocious failure against transmission system will be removed. At the end, frequency analysis, using Abaqus software the test was done on the shaft and the results obtained, compared with the actual test.

Coating has an expended usage in different industries in order to prevent the contact with the corrosive environment. Beside, coating’s quality is connected extensively to the position of the surface under the layer. In this essay different ways of preparation of the surface have been studied and compared before the applying the coating which includes the mechanical preparation (such as grinding, brushing and blasting) and also implementation of the conversion coating as a mid-cover. Organic coating of epoxy was applied after the preparation of the samples of aluminum alloy 5083 and also corrosion resistance, coating adhesion, mechanical strength, and the use of color in different samples were compared. Polarization method was used to compare the strength to corrosion in order to study the characterization of conversion coating and to obtain an optimized situation for applying it. By studying experimented samples, it was concluded that the implementation of mechanical preparation has a negative effect on the characterization of mechanical components. If roughening the surface is done consumedly to increase the effective area, it causes corrosion properties. On the other hand the consumption of color can be increased to 3 times more than normal rate, so in comparison wet blast method has more disadvantages. Applying conversion coating as a mid-layer has improved considerably the corrosion properties, and also in this method the consumption of color is equal to not prepared samples. This method has a low rate of cost and relatively it has fast and simple operations. This method had not been already used in coloring and it is a new method for improving the coating’s properties on aluminum surfaces.

Nowadays, most high speed and big vessels are made of fiberglass. These materials are replaced with metals because of their better resistance against corrosion, higher strength rate per weight and easier shaping. Most of these vessels are made with hand layup method. To achieve a higher quality these traditional methods must be replaced with more appropriate methods. One of these modern methods is vacuum infusion process (VIP) which reduces the weight and removes the bubbles in final product and causing better strength than the hand layup method. In this method of fabrication process, there are different parameter effecting the time and quality of resin injection. This research includes the effect of actual pressure difference in theoretical, numerical and experimental methods. At the end, after investigating the parameters, it is proven that the optimized pressure different, must be calculated to reach the minimum injection time. In lower pressure difference, numerical and theoretical results are better matched with the experimental results, while in higher ΔP the results are different.

The last ring of the arrangement is for a craft choice propeller, which is important in reducing fuel consumption and speed for this purpose the full-scale test using one of the methods are reliable. Full-scale testing, the need for accuracy and reliability of the design to reduce potential errors as possible. This paper compares two propeller for the propeller recommended by the manufacturer Submersible target, Besides presenting the design and testing of full-scale measurement technique, commonly used for the purpose of the two propeller have been compared in terms of efficiency and performance ¡The results show that, to reduce cost, increase speed and reduce fuel consumption can be used of craft propellers old generation, in new craft.