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| | HOW TO CHOOSE THE CORRECT BOW THRUSTER | |
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| | Having a bow thruster gives you positive control of your boat, even at low speed and regardless of wind, current or tight docking conditions. VETUS offers both electrically and hydraulically driven bow thrusters, to suit supplier a wide variety of boats manufacturer. Working in close collaboration with the Maritime Institute Netherlands (MARIN), the world-famous hydrodynamic laboratory, VETUS has optimised the performance of its marine thrusters. This has been achieved by utilising a unique propeller blade profile, which creates little or no cavitation. As cavitation produces unwanted noise, this new blade design offers a major reduction in the operating sound levels for VETUS bow thrusters. Moreover, the application of this new propeller has reduced the current consumption by up to 10%. | |
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| | This overview of the relevant factors will help in the selection of the correct model. GENERAL INFORMATION VETUS bow thrusters are equipped with a streamlined bronze tail piece. This has proven to be stronger and more durable than other materials sometimes used, whilst creating the minimum of turbulence, lowest efficiency loss and lowest noise levels. The metal underwater parts are protected by a zinc anode, which is fitted as standard. VETUS propellers for boats are corrosion-free and on thrusters up to the 310 kgf model, are made of synthetic materials. Owing to their low weight, the maximum thrust force is obtained very quickly and with a minimum of energy. The propellor blades are specifically designed for use in a tunnel and are shaped in such a way that the thrust is equal to both starboard and port. Because of this, cavitation is largely avoided and noise levels are considerably reduced. Thruster models over 310 kgf have bronze propellors as standard, for increased strength and durability. Bronze propellers are available as an option for the 220, 230, 285 and 310 kgf models. The smaller the diameter of tunnel, the lower the resistance will be while under way. In addition, a smaller tunnel diameter allows the tunnel to be installed further forward, which increases the turning moment of the boat. Tunnels are available in aluminum, GRP or steel to suit different hull materials. Practical tests demonstrate that acoustic material type ARM can help to reduce bow thruster noise. A coat of ARM compound, or a layer of sheet material around the tunnel can reduce the sound level by about 3 dB(A). Two layers can create a reduction of up to 7 dB(A).VETUS bow thrusters use high efficiency electric motors manufacturer for maximum power and longevity. In contrast with modified starter motors, these allow continuous running at full power for several minutes. A range of kits are available to enable any VETUS bow thruster to be used as a stern thruster. | |
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| | The lateral wind draft area | THE INFLUENCE OF THE WIND The force applied to the boat by the wind is determined by the wind speed, wind angle and the lateral wind draft area of the boat. When the wind speed increases, the wind pressure increases quadratically. If the wind blows at right angles to the boat, this wind pressure is most difficult to counter. However, this is seldom the case and as most boat superstructures are fairly streamlined, a reduction factor of 0.75 is generally applied, when calculating the wind pressure. | |
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| | | | | | | | | | | | | | Wind pressure N/m2 - (kgf/m2) | | | | | | | | | | | | | | | | | | | | | 75 to 123 - (7,7 to 12,5) | | | | | | | 125 to 189 - (12,7 to 19,2) | | | | | | | 191 to 276 - (19,4 to 28,2) | | | | | | | | | | |
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