Basic Prop Geometry Question

[Fastjeff57]

I seem to recall someone on this site saying they prefer a large blade area AND low pitch prop to a small blade area AND high pitch prop.

Humm... Was wondering what the advantage of each would be. One would suspect the former set up would plane off easier, and the latter possibly having a higher top speed. but...

Jeff

[champ20B]

I seem to recall someone on this site saying they prefer a large blade area AND low pitch prop to a small blade area AND high pitch prop.

Humm... Was wondering what the advantage of each would be. One would suspect the former set up would plane off easier, and the latter possibly having a higher top speed. but...

Jeff

Well, a low pitch generally provides greater moving force and having a bigger blade gives it efficiency at lower velocity. These are not for high performance hulls. A higher pitch prop is generally for a higher velocity application. This is where it gets "tip for tap" on blade area. Basically in a high performance situation, there is a specific balance of necessary efficiency and unwanted friction. Basically, the faster a prop turns, the denser the water contact is. In such a case, a narrower blade would be sufficient at a point to where larger area would only generate unwanted friction. This can only be determined in individual cases through extensive testing and efficiency calculations afterwards.