For long engine life and overall performance is only needed the right propeller. But not a single screw is right all the time. If you change the way the boats and marine engines, you must change the propeller, too. The propeller is wrong not only affect performance, but can quickly destroy the engine.
If you purchased your boat and engine as a combined package, the dealer for the propeller under the pre-delivery-rigging have votedProcess. Be sure to check with the dealer. But things can change, while the owner of the boat. The concessionaire will be selected on an engine based mean exposure for your boat. But you can add the heavy elements that will change this important selection criterion for the propeller.
Outboard powered houseboats and pontoon boats are the main examples of craftsmanship required to collect heavy equipment. Maybe you're just starting to tow a water skier. Maybe you have the original engine as an auxiliaryTo feed a small sailboat, and is used as a primary drive for lightweight sculls. Or maybe you are visiting on our mountain lakes taken. Extreme differences in elevation can affect the operating range of the engine. If the engine was based on sea level, the operation in a lake at high altitude require different support to keep the motor speed in the normal range. In fact, all these changes will require a renewed support.
The objective of the rigger engine is to ensure that yourEngine reaches a certain number of revolutions per minute (rpm) at full speed under normal conditions of use for your boat. Neither more nor less. In general, this comes at a maximum speed with a tolerance range 800-1000 rpm. The range is still listed in the shop manual for your engine, and is usually listed in the manual.
Before proceeding with an explanation of the theory of the propeller, let us define some basic terms helix.
PropellerTerminology
Pitch. This specification is the theoretical distance in inches that the propeller moves forward or backward in a complete circle. Think like a screw propeller, making its way into water.
In diameter. This is the straight line distance from the center of the hub to the farthest tip of the propeller blades, sometimes two.
Cupping. This term describes the "curl" at the trailing edge of a propeller blade. Cupping is used by engineersIncrease the theoretical slope of the blade, giving a better grip on the water.
Slip. This is associated with bad luck. The theoretical distance a propeller moves through the water in a round (step) to the fact that the propeller actually lose some distance with gliding through the water. Typically, a standard engine is somewhere between 10 and 30 percent have hatching, depending on their design and use.
Blade thickness. The design of the propeller and thematerial used determines the thickness of the blades. Ideally, the knives are made as thin as possible in order to reduce the resistance. But they also need stronger.
Cavitation. There are many causes of cavitation, including excessive stress on the propeller, the vapor bubbles on the leaf surface to create. The effect is to lose its grip on the engine and turn on water at high speed. Cavitation can through various front of the engine noise underwater, so something causedJust like a barnacle to the bottom of the engine, gearbox or a sonar transducer near the centerline of the boat attached. Notches on the leading edge of the propeller blades can also cause this condition. Cavitation can cause extreme damage to propeller blades, deep dimples, and ultimately, the loss of the blade
Ventilation. This is such a state of cavitation, but is usually drawn from the surface. Sometimes caused by too much "off" settingthe engine, or with the engine mounted too high on the rear. Sometimes the gases are drawn in the area of the rotor blades. His unit has a bottom plate of the ventilation air is drawn down to prevent the propeller surface.
Rake. This is the angle between the sloping rear propeller hub and the blade. High-cut angle are used for motor boats to pass an increased tendency for aeration and cavitation.
In addition to the basic definitions, it is necessaryknow some more facts to work your way through the basic process of choosing the propeller.
The constructor method for the identification of the basic helix (in addition to the model number of the side) is used to enter the diameter and then the first pitch in inches. They are usually stamped on the propeller hub. For example, support stamped "14 x 17" has a diameter of 14 inches and a wheelbase of 17 inches. Other markers are specific to the manufacturer, stating thePropeller model and the general type.
What is the specific type of propeller for your application, you must obtain a copy of your master brand engine parts catalog (available for free on all merchants) and look at the list of recommendations helix. It 'set for specific performance and the type of use, as well as the weight or the type of boat. Just find the boat in its class (pontoon boats, ski boats, speed boats, etc.) and the power of the engine, and you'll be closer to the rightProp for your boat.
To determine the exact diameter and pitch that best suits you to study in detail the specifications table. Diameter, for example, will be determined by approximate normal speed for your boat, and usually the manufacturer's specifications on this list several possibilities.
To determine exactly the right tone, you need to do some tests on the water. I must stress that the only way to do this test accurately with a tachometer. IfThe boat does not have it, you should let the dealer do this work with his instrument.
Here is the sequence of tests:
1 Refer to user specified revolutions per minute (rpm) the engine is designed to establish reach full capacity. This is sometimes referred to as the full throttle or WOT.
2 Use your existing propeller, set a "benchmark" for several test runs in the water relatively calm. Customize your engine trim anglemaximum speed. Take your maximum RPM of the engine and top speed is achieved when you have a tachometer.
3 If the speed exceeds the recommended range full throttle, you need more space. You can install and test the next largest manufacturer of propellers and again. On average, the change in tone from a speed of 250 cm propeller revolutions per minute, is changing. That is, the motor speed of 250 revolutions per minute, if you reduce the height of an inch, and the acceptance of 250 revolutions per minute, when you increase the pace ofinches.
4 If the recommended rpm full throttle below the tolerance, install the propeller to the next lowest available, and testing.
You have reached the optimum setting if only you can load the maximum speed for the motor to the boat, as it should be indicated. This should also give the best speed.
For installations on non-planing craft, as heavy lifting and auxiliary sailboats, speed is more critical evaluation of this specificProcess. If the boat is not to reach the speed of the hull may be too coarse grid prevents the engine from its maximum development speed and then full power.
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