Labbed vs. stock props

[Boat 405]

Ok so I'm trying to figure out my props. I'm running a 24 pitch on my 25' Daytona. I bought a 26 pitch prop for two reasons. One for a spare and two to try to get more MPH and lower cruising RPM.

Now when I look at the two props the shape of them are basically the same but the blades seem thinner on the 24 than the 26. Especially the trailing edge is squared off clearly done by a machine on the 26, where the 24 is thinner and more knife edged on the trailing edge.

It got me to thinking that my friend who has a 22 pitch prop that was the same as the 26 that I have with the squared off trailing edge. When we tried my 24 pitch prop on his boat the difference was almost not noticeable. Now i wonder if the 24 that I have is labbed and didn't know it. I've heard that a labbed prop performs similar to a pitch smaller than what it is.

I may be way off on my thinking here but, thought I would ask because I'm pretty much a rookie when it comes to these propeller things. :skull

 

[Outdrive1]

I don't think you can visually see the difference in pitch between a 22 and 24 pitch prop.

Sure you could see if it has thinner blades. Depending on who worked on it it may or may not be" labbed" or balanced.

I kinda feel like unless it came from Mercury Racing as a labbed prop who knows what you got or what's been done to it.

 

[AzGeo]

WHO did the 'lab work' ?

If you have not addressed the 'hull bottom' first, then why think that the cost of any 'labbed prop' will improve results, for the money spent ?

There are a lot of 'prop experts' and they all have different methods of doing things .

Straight pitch, progressive pitch, short cup, mid cup, full cup, blade rake, blade surface area .

If it were a 'tire on the road' we all could figure it out mathematically . But when it comes to 'slip VS drag', all perfect calculations go out the window .

Mercury Marine has their 'ideal numbers', and everyone else has theirs .

I would consider a 'labbed prop' for speed runs, poker runs, laying down the law for friends .

I sure as hell would not chance wasting a $1000+ prop going to the 'sand bar' one weekend .

I can't see risking a 'hand finished, razor thin prop' on dragging, inflatables, bar-b-ques, and sand chairs around the lake .

Call me old fashioned, but money does not grow on trees .................


edit; WTF is 'knife edged' on the rear of any blade ? Does it have a cup ? Does it curve up along the trailing edge of the blade ? Does it have an abrupt 90 degree angle on the trailing edge of the blades ?

 

[Outdrive1]

WHO did the 'lab work' ?

If you have not addressed the 'hull bottom' first, then why think that the cost of any 'labbed prop' will improve results, for the money spent ?

There are a lot of 'prop experts' and they all have different methods of doing things .

Straight pitch, progressive pitch, short cup, mid cup, full cup, blade rake, blade surface area .

If it were a 'tire on the road' we all could figure it out mathematically . But when it comes to 'slip VS drag', all perfect calculations go out the window .

Mercury Marine has their 'ideal numbers', and everyone else has theirs .

I would consider a 'labbed prop' for speed runs, poker runs, laying down the law for friends .

I sure as hell would not chance wasting a $1000+ prop going to the 'sand bar' one weekend .

I can't see risking a 'hand finished, razor thin prop' on dragging, inflatables, bar-b-ques, and sand chairs around the lake .

Call me old fashioned, but money does not grow on trees .................

I tend to agree. A labbed finished prop in parker is useless. You put your boat in gear in the keys or at any riverside bar and you kick up sand. Labbed props break easy. Throw blades. And once they are scratched up from sand they aren't balanced anymore. Balance is key to efficiency just as pitch and blade thickness is.

Waste of money to me.

 

[Boat 405]

WHO did the 'lab work' ?

If you have not addressed the 'hull bottom' first, then why think that the cost of any 'labbed prop' will improve results, for the money spent ?

There are a lot of 'prop experts' and they all have different methods of doing things .

Straight pitch, progressive pitch, short cup, mid cup, full cup, blade rake, blade surface area .

If it were a 'tire on the road' we all could figure it out mathematically . But when it comes to 'slip VS drag', all perfect calculations go out the window .

Mercury Marine has their 'ideal numbers', and everyone else has theirs .

I would consider a 'labbed prop' for speed runs, poker runs, laying down the law for friends .

I sure as hell would not chance wasting a $1000+ prop going to the 'sand bar' one weekend .

I can't see risking a 'hand finished, razor thin prop' on dragging, inflatables, bar-b-ques, and sand chairs around the lake .

Call me old fashioned, but money does not grow on trees .................


edit; WTF is 'knife edged' on the rear of any blade ? Does it have a cup ? Does it curve up along the trailing edge of the blade ? Does it have an abrupt 90 degree angle on the trailing edge of the blades ?

It has very little cup on the trailing edge the trailing edge is very thin where as the others have a noticeable amount of cup and and abrupt 90 degree angle on the trailing edge of the blades

 

[Outdrive1]

It has very little cup on the trailing edge the trailing edge is very thin where as the others have a noticeable amount of cup and and abrupt 90 degree angle on the trailing edge of the blades

Try a bone stock 24 that's never been worked on and compare rpm and speed. Theoretically one right after the other so temp and weight is as close as possible.