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Boat propellersA boat propeller is not just one of many parts of a sailing vessel. It is one of the major components of any sailing craft, whether a yacht, a sloop, or a cruise liner. In tandem with the boat?s engine, it is what enables you to slice through the water at good speed and provides for secure handling.
What is a Boat Propeller?
A boat propeller is a device comprising of a shaft with blades that spread out from the shaft in such a way that the spinning motion of the blades moves the boat (propels) in a specific direction through the water. In its abbreviated form, a propeller is referred to as a prop and or a screw.
What determines the size of a Boat Propeller?
You?ll be surprised to know that it is just 2 numbers that determine a propeller?s size.
(1) The diameter of your boat?s propeller is the first number; this is measured from the hole of the propeller shaft to the very tip of the blade
(2) The pitch of your boat?s propeller is the second number, this is the distance the propeller will move in a forward direction in one complete revolution. It should be noted that this distance is merely in theoretical terms, and not the actual distance.
The above-mentioned numbers are in inches.
Have a look at your boat propeller the numbers will be etched either between the blades, or around the hole of the propeller?s shaft.
The pitch number is of higher priority, as it is this number that will provide the appropriate operating range of your boat?s engine when moving at full speed [known as wide open throttle (W.O.T.)]
What are the different types of boat Propeller Materials?
Aluminum Propellers: These propellers score over other materials in terms of cost, as they cost fewer dollars. Repairing is also comparatively easy and inexpensive. When you first buy a boat, it is likely that the propeller is one of aluminum. The major drawback of an aluminum propeller is that it is likely to have a shorter life span than other types. Also, the blades of an aluminum propeller have some flex, which affects the efficiency of the boat.
Stainless Steel Propellers: You will be paying more dollars for a stainless steel propeller than for an aluminum one, but its huge advantage is that it scores high on speed. It thus provides for faster cruising through water. It also has a longer life span. Even better, there is none or little blade flex.
Bronze Propellers: If you are likely to participate in a tournament, you can install a bronze propeller on your cruising vessel. It tends to give a great performance and, though expensive, is good enough to last a long time. It also has negligible blade flex.
How many blades does a boat Propeller have?
At one time, boat propellers had just two blades. Today, some merchant sailing vessels have up to seven blades. However, most boats have three-blade or four-blade propellers. When you wish to start off and accelerate real quickly, a four-blade propeller is ideal. This is especially the case if you are planning to have a stint of water skiing with friends hooked at the back of your boat on the skis. Also, if your sailing vessel is on the heavier side, a four-blade propeller is a good option. A four-blade stainless steel propeller provides for very good stability and economy in terms of fuel. Of course, you will be paying more dollars for a four-blade propeller than for a three-blade one.
What are the common problems that can occur in a Boat Propeller?
If there is even a slight inaccuracy in the pitch or the blade elevation, the boat propeller can begin to vibrate.
Black smoke can emanate from the boat propeller. Determining the correct pitch required for your boat?s engine RPM will help to eliminate this problem.
A major problem that you can face is what is known as cavitation. This occurs when vapor pockets (cavities) are formed during high cruising speeds, resulting in a noisy boat propeller. It subsequently causes the surface of the propeller to get worn out. Today, specially designed blades drastically reduce this problem.
When the boat?s propeller that has been installed near the water surface sucks air, vibrations are caused, and the boat loses some of its power. The surface of the propeller, however, does not get seriously damaged. This problem is known as ventilation. It is therefore advisable to install the boat?s propeller deeper in the water, away from the surface.
What are the basic aspects to be considered when replacing a Boat Propeller?
. The type of boat you own and its length
. The type of motor that is installed in your boat and its horsepower
. The type of propeller that is already installed and its size in terms of diameter and pitch
. The RPM specifics of your boat?s motor when used with the current propeller.
What security and safety measures should be taken for a Boat Propeller?
. A lot of boat owners have been aghast at the theft of their propellers. To secure your boat propeller, install locks specially designed for the purpose and outsmart the thieves.
. Safety, of course, is of prime importance. The blades of a boat propeller are very sharp, and can easily hurt someone playing in the water when parked at a dock, or cause injuries while having it towed. What is required is proper protection in the form of a propeller cover. These boat propeller covers are available in the market made up of durable plastic and with the appropriate hardware. These also tend to be in bright glowing colors for easy visibility.
Generally costing over $100 (maybe less when bought online at discounted prices), a boat propeller is a vital component of your sleek vessel. Make sure you maintain it well, check it regularly and have it repaired / replaced at the slightest sign of wear and tear. Otherwise, the efficiency of your boat?s functioning will be seriously affected.
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