prop barrel ?'s

[MBAKER]

A few prop questions...

Some aluminum props have a raised 'wedge' ( for lack of a better term) on the barrel around each blade some dont, I dont think ive ever seen them on stainless props. What is the purpose of this raised area?

What does the lenght of the barrel affect on a prop? I have seen some props that have a longer barrel than others, and have seen talk about cutting the barrel shorter to tune the prop.

 

[Frank Acampora]

Re: prop barrel ?'s

I think the term you are referring to is a "Flare." It is there to modify water flow and contain exhaust, especially in reverse when exhaust would foul the prop blades. A longer straight hub will have the same effect. OMC used to have a ring around the outside of the hub but I believe newer models have discontinued this. Suffice to say: The manufacturer has tested the designs and incorporated that feature which will give best over-all performance.

 

[MBAKER]

Re: prop barrel ?'s

I should clarify, the wedge I was talking about is on the side of the barrel at the base of the blade, not the flare on the end. Its like a raised portion of the casting around the base of the blade.

 

[Frank Acampora]

Re: prop barrel ?'s

Stainless props are cast by lost wax process and the mold is a single friable piece that is sand blasted off after cooling. THUS: no excess metal is necessary.

Some aluminum props are cast with a re-usable three piece mold and the wedge is there so the mold can be removed after cooling. The wedge serves no purpose and does not either enhance or decrease performance.

 

[jerryjerry05]

Re: prop barrel ?'s

I believe the extra metal is there for strength.
Like adding a boss under a screw or bolt.
It helps to strengthen the base so the blades don't twist off under acceleration.