Familiarizing With Boat Props Terminology

 

Imagine yourself in a situation wherein you have landed in a store that specializes in selling marine equipment and need to buy boat props for your company’s requirement. Unless you are cognizant with the nitty-gritty of this niche in terms of its nuances and associated jargon, chances are high that you would be totally lost and would not even know where to begin. Every sea-faring vessel needs to be fitted with a propeller to be able to move in water and in colloquial terms these mandatory parts are referred to as marine props. Cultivating an in-depth understanding on the subject is a must for anyone concerned with the industry.

 

One of the best ways to begin an acquaintance with boat props entails learning to identify each of the parts and their contribution to the entire operation. Every prop comprises of a hub which has blades attached to it that may vary from being three to four. While it is the hub’s responsibility to connect the blades to the engine’s drive shaft, the angle at which the blades are placed is what determines the ability of the boat to move forward in water. There are two edges to a blade in marine props namely leading edge that cuts through the water and trailing edge that marks the side opposite to the leading edge.

 

Boat props often feature mathematical expressions engraved on their hubs that read something like 15” X 12.5” wherein the inverted commas are indicative of inches. As per universal rules governing marine props, the first number is indicative of diameter and the second denotes the pitch. Diameter is representative of the number that is twice the distance between the hub’s center and blade’s tip and pitch is the forecasted distance that the propeller is expected to cover while in water over one revolution. However, pitch is not a reality because invariably the actual distance that is covered is lesser, the difference between them being termed as Slip.

 

As a norm, prop slip is expressed as a percentage and is likely to vary from one vessel to another wherein the lower its value the more efficient is the system. Although it is usual for boat props to feature right-hand rotation, left hand props are fitted in case of double engines since it is imperative to counter the torque generated that may sway the steering to one side. There are times when marine props are tweaked a little so as to bring about an improvement in their performance. This entails curving the trailing edge of the prop blade and subsequent to having received this special treatment, the blades are referred to as being cupped.

 

Few other terms that you come across in context of boat props are splines and rake – the former refer to the teeth that grace the drive shaft and it is this numbers that ascertains the type of hub that will fit into the shaft. Likewise, rake is the angle which the blades form with the hub and the reading starts from 0’ which means that the blades form a right angle, meaning 90 degrees, with the hub. A positive figure like 45’ indicates and angle of 45 degrees added to the 90 degrees while something like -20’ would indicate a forward rake of 20 degrees less than 90 degrees. So now when you walk into a shop to buy marine props, you will be in a position to make an educated choice.

 

Buying boat props without being aware of terminology associated with them is like shopping for clothes without being aware of details like fabric, design and fitting. Cultivating an understanding of related jargon pertaining to marine props not only helps on an industrial scale but also while making a purchase for personal use.

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