Going from a round ear prop to cleaver

[biggdave92]

Is there a general rule of thumb on how much to go up in pitch when going from a standard REB prop to a cleaver? I am currently running a 10 1/8 x 12p stainless. Im turning it 6250 rpm's. Motor is a 3 cyl yamaha 25. I am looking at picking up a RH cleaver. Thanks for any help!

[genea01]

what kind of boat are you going to be running

[biggdave92]

i am currently running a 1542 alumacraft flat bottom jon, but i am looking at a weldbilt 1548. both flat bottom.

[genea01]

that is a long boat to run a 25 on but i think you would be better off running a chopper on that boat with 8'' set back you need alot of lift to run that size boat but it can be done very easy 18'' pitch chopper should do you, email ron hill or look on ebay he has them there. both of those boats run real good

[biggdave92]

I am a newbie when it comes to speed props. would you be so kind as to explain the characteristics of a chopper and cleaver. i appreciate it!

[Skoontz]

I am a newbie when it comes to speed props. would you be so kind as to explain the characteristics of a chopper and cleaver. i appreciate it!

A cleaver is a surfacing, or transom lifting propeller. If you have a boat like a tunnel or hydro where they use the wind to help lift the bow, a cleaver will help lift the transom to reduce the drag.

Cleavers have been known to work on Vee and semi bottoms, but the guys running them usually went through allot of mousing around to find one that works.

Chopper props are bow lifting props and work very well on Vee, Semi Vee, and John Boat type rigs.

[JohnsonM50]

A cleaver is a surfacing, or transom lifting propeller. If you have a boat like a tunnel or hydro where they use the wind to help lift the bow, a cleaver will help lift the transom to reduce the drag.

Cleavers have been known to work on Vee and semi bottoms, but the guys running them usually went through allot of mousing around to find one that works.

Chopper props are bow lifting props and work very well on Vee, Semi Vee, and John Boat type rigs.
Cleavers are made as low to high rake as well as others, the typical characteristics being less rake, less bow lift, more rake more bow lift. From the few Ive got they will run shallower & do lift better overall than my others. That being a few drops in an ocean of props means little, the best you can do is try before you buy if possible. Id be carefull not to over pitch & bog the motor. When that happens the right pitch will out accelerate & out run the prop thats too much. Good luck

[Mark75H]

True, I used to have a super low rake cleaver that I used on short courses. It held the boat in the water like it was on rails. People used to ask me why I drove so close to the buoys ... I let someone else drive the boat and they drove it the same way ... I asked him why he drove so close to the buoys ... his answer ... "Because I can!" ... the same thing I had been telling people.

[biggdave92]

So does anybody have a 10 x 18 Chopper for a 98 Yamaha 25hp I could try? I'll pay shipping both ways. I have a UPS account so I could send UPS to your house to pick it up. Does Ron have a return policy so if i get the wrong one I can swap it out?

[JohnsonM50]

So does anybody have a 10 x 18 Chopper for a 98 Yamaha 25hp I could try? I'll pay shipping both ways. I have a UPS account so I could send UPS to your house to pick it up. Does Ron have a return policy so if i get the wrong one I can swap it out?

All my props are 9/16 or 11/16 pin drives. An idea tho is to get actual speed & rpm with what you have as a benchmark. Then do the arithmetic.
Pitch X RPMs divided by 12 X 60 divided by 5280 [mile]. That will equal potential speed before figuring the gear ratio. [For examples sake] if your gear ratio is 16:21, divide 16 by 21 & you get 0.762:1 Multiply the above potential speed by the ratio [0.762] And you get the fastest possible speed your boat could go if your prop was 100% efficient & there was no resistance. Subtract what your boat actually does & you have an answer representing the percentage of slip & resistance you encounter. It might be as low as 60%, or as high as 90%.
Cleavers tend to be very efficient at speed. This on the other hand will tend to hold back the RPMs if your near the motors limit. I hope based on your running a known pitch now this helps choose a starting point. As far as buying testing & having changes made youd need to talk to the pros. Some change can be made to any prop. Good Luck:cool:

[biggdave92]

Here are my numbers:

1.85 ratio
6250 RPM's Tiny Tach
36 mph GPS
10 1/8 x 12p Prop

[JohnsonM50]

Here are my numbers:

1.85 ratio
6250 RPM's Tiny Tach
36 mph GPS
10 1/8 x 12p Prop
That works out to be a potential speed of 38.4 mph making your efficiency well into the 90 percentage. Thats VERY good as is. Next figure what your motors safe hi-est RPM is & where the most torque is. You might not want to increase pitch, Ive seen it enough that less is sometimes more & what seems should be is often nearly opposite. Unless your boat accelerates REAL hard more might slow it down. Since your present prop is doing what its supposed to & you want to go faster you need to look at the whole thing.. Weight & distribution, motor set up. When/if you do change something take notes. Try not to do too many things at once so if something does help you know what change it was.

[Ted March]

Maximum Potential MPH (No Slip )

MPH = RPM X PITCH X GEAR RATIO / 1056

Gear Ratio = 1.85 / 1 = 1/1.85 = .5405

MPH = RPM X PITCH X G. RATIO divided by 1056

38.388 MPH = 6250 X 12 X .5405 divided by 1056

GPS = 36MPH

Slip = 2.388 MPH

Slip = 6.22%

[trentbmx95]

I have a 1996 Evinrude 88 SPL 2 stroke V4, and im wondering if replacing the stock REB prop with a cleaver racing prop would harm it or mess with the exhaust or have any cons with it. It is a 13 spline and im looking for a 26 - 28 pitch 13" - 14" in diameter racing cleaver prop. From my amiture thinking i would think replacing the REB prop with a cleaver wouldnt have any cons EXCEPT maybe how the water flows to the prop. Would the exhaust get in the way making the prop catch the exhaust fuems wich would make it not perform its fullest performance? I dont know im leaving it up to you guys, please help me!!