Modification Octura X670 - how

[Koban Rado]

I have a prop Octura X670 / 2

How to process X670 prop, it will have characteristics X470.

Be corrected:

A: in diameter

B: cut back

C: texas cut, ....??

On my boat Laser45, how with stock engines using Octura X470 / 2 and it works perfectly.

 

[lohring]

I assume you are running a modified Zenoah or similar engine in your Lazer 45. The standard heat race prop in my area was the X470 3 blade for years. The main modification was to back cut it like your line B but tapering from around 1/8" (3 mm) deep at the hub to nothing at the tip. This reduces both area and pitch at the hub without changing the pitch much in the area where the prop works. The X670 has more pitch and the two blade will have less blade area than the X470 3 blade. That alone should load the engine similarly for both props. You have added 50% more pitch (6/4) but reduced the blade area by 1/3.

Props are much more sensitive to diameter changes than to pitch or blade area changes. Be very careful not to change prop diameter when back cutting or Texas cutting. Often a slight rounding of the prop tip seriously unloads the prop.

Lohring Miller