Learning About Your Propeller

by Super User
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There is so much more that goes into a boat propeller than most people realize.  There are terms that we in the business use that are often times not understood.  Here is a good overview of a few of those terms to help you better comprehend the work that goes into perfecting your prop: Propeller Facts

What is propeller pitch?

Pitch is defined as the distance a propeller would move if it turned one time through a solid. Think of a screw going into wood. The distance it goes into the wood with one rotation is the pitch. When applied to boat propellers, the concept is a bit more complex since a 21" pitch propeller won't actually travel 21" through water due to variables such as drag, aerodynamics, ventilation, and cavitation. The difference between the theoretical pitch of a propeller and its actual progression in the water is called "slip." For the most part you shouldn't need to worry about either of these unless you suspect that your propellers pitch may be wrong for your boat and your boat motor. In this case, you can try to determine it yourself HERE or give us a call, and we'll help you find out if you have the right propeller pitch. 

What is propeller cavitation?

Propeller cavitation is the formation of air bubbles on the propeller due to pitting on the prop's surface. It usually occurs as a result of damage to the propeller and will be felt in the form of vibrations. Unless you are an expert in propeller repair and have the appropriate tools yourself, cavitation should be addressed promptly with a professional boat prop repair shop as it can damage the propeller itself as well as reducing efficiency and creating an uncomfortable ride.

What is propeller ventilation?

Propeller ventilation is when the prop sucks air, which is often caused by having the boat engine trimmed to high. It can also occur when boating at high speeds and jumping waves or in sharp turns, either of which can bring the propeller close to the surface of the water. Ventilation can cause the engine to over-rev and a signficant reduction in thrust. Unlike cavitation, ventilation issues can often be fixed by the boat owner fairly easily. If you have questions or concern, give us a call!