Propeller Language; or, Do You Speak Propeller?
Published: Monday, November 21, 2022 12:00 pm
By: Professionals of Henry H. Smith Co.
When we think of all the new purchases we can make to improve our boats, we often consider a new propeller. A new propeller offers many options that can improve performance, fuel economy, top speed, hole-shot, appearance, reliability, and several other attributes.
When we consider changes to a new prop, the elements or features that can improve the performance can also degrade performance. It is best to discuss these considerations with a propeller professional to make sure the changes are effective, but you have to speak their language. Just as there are computer, technical and medical languages, there is also a propeller language. Here is a crash course – Propeller 101 – a few of the most frequently used terms.
The very basics in propeller language don’t require a great deal of explanation as they are very intuitive; like diameter, the outside dimension from tip of the blade to the center times two, or the pitch, which is the theoretical progression of the propeller as it ‘screws’ through the water, measured in inches.
Other terms are more propeller specific and not as easily understood. These are words like rotation, rake, cord, cup and skew which have somewhat unique meanings when it comes to propellers. Rotation is defined by looking at the propeller from behind the boat, identifying clockwise as right hand (RH) and counterclockwise as left hand (LH).
Rake is a measurement of the blade’s angle perpendicular to the propeller shaft, in either forward or aft direction and can effect the angle of the blades rotating in the water, effecting bow lift. Cord refers to the thickness of the propeller blades while skew defines the asymmetrical shape or sweep, with or against the rotation.
There are many, many more words and terms in the propeller language. The aforementioned will get you through a basic discussion with your propeller pro to the point of being able to decide which is the best new propeller for you, your boat and your specific requirements. Now that conversation with your propeller professional will be that much less stressful or intimidating and will be much more constructive. No translator required!
About the Author
Founded in Detroit by Henry H. and William H. Smith, the company continues to employ third and fourth generation members of the family, carrying on a legacy established in 1900 to be your Marine Drive Specialists. Learn more at www.henrysmith.com.
tags: Education, Propellers
