PDA

View Full Version : Cleaver Prop



flametamer
12-17-2000, 09:28 PM
I am currently running a Mercury Mirage Plus 48-13246 A50 23p Prop. on my 1994 22' classic. This porp.seems to work well and rpms seem to match.I have a Mercury 454 w/ bravo drive. I want to try other props and found a mercury stainless three blade cleaver. 14"x30p.Has anyone had any luck with this combo?

Tom on Lanier
12-17-2000, 10:19 PM
Flametamer - you have one of the best props for your combo right now. You would need a lot more power to turn a 30" prop, and I mean a whole lot more power. Don't go there or you won't go!

------------------
Tom
"Tomahawk"

CDMA
12-17-2000, 11:07 PM
1 inch of pitch = 200 rpm

So 7 inches should be 1400 rpm

You will be lucky to plane off.

Chris

rayjay
12-18-2000, 10:06 AM
I'm still learning about props, but wouldn't the 14" diameter effect the overall "size" of the prop? If I remember right there a relationship between diameter and pitch, if you increase the diameter it has the same effect as increasing the pitch, and if I imagine the converse is true. Wouldn't a 14" prop be a decrease in diameter and therefore would be more comparable to a lower pitch than 30?

What does a cleaver do?

rayjay

CDMA
12-18-2000, 11:02 AM
You are correct. The smaller the diameter is equal to less pitch. However what is the diameter of the mirage? I am not sure it was given and I am not to familiar with Mercruiser stuff yet.

A cleaver prop is essentially a ventilating prop. One of the biggest problems with propellers is cavitation. A cleaver prop is creating cavitation on purpose. It creates a low-pressure area that the back end of the blade encounters. What it is essentially doing is going past cavitation. It is removing all water from the back 60% of the blade where cavitation is more common. In the commercial world this type of design id also called a super cavitating prop. Until relatively recently they were very common on high performance stern drives. With some new designs such as the mirage and the Volvo ultra they were phased out. They are still very common and more efficient in surface drive and raised x dimension applications. That's first year NA for you. Give me to senior year then I get a course by the guy who has designed every prop for every nuclear sub the navy has ever produced. Then I will tell you more.

Chris

boldts
12-18-2000, 11:23 AM
Ray/Jay,
My little bit of prop knowledge and playing with my own boat and prop, You are correct. A cleaver type prop has a pointed tip rather than the round ear look of most props. A cleaver prop is also meant to be run in a ventilated manor or with more trim than the round ear props. Because of this, you will usually need to run more pitch or diameter with a Cleaver type prop. One word of caution with these props. Because of the larger diameter and or pitch, they require a engine with good torque. Also, if you like to fly the boat off wake or waves, be ready to back-off the throttle when the prop re-enters the water. Because these props grab so hard, I've known and seen people who have bent valves in their engines. Especially with the small block engines. A Cleaver prop I believe also lifts the transom of the boat rather than the bow. If you don't have power trim with the drive you are using, this is not the prop to run on your boat. Now that I've said that, prop diameter and pitch work hand in hand. If you run a larger diameter prop, usually you will run less pitch. If you run less diameter, you will also usually run more pitch. If you only need to drop the RPMs 100 or 200, try adding cup to the prop before spending $500 + for a new prop. I hope this helps.

Scott Boldt

RickR
12-18-2000, 06:29 PM
flamethrower
My 95 22 Classic was built with the standard X Dimension. If your 22 is set up the same way a cleaver more than likely will not improve performance.
Alot can be gained through prop tuning. A thinned prop will give you more speed but will not be as durable.
If I were going to try another prop it would be a Hydromotive.
BTW I took Tom's advice last summer and bought a 23 Mirage Plus for my 22. It made a SIGNIFICANT difference in the 22's performance over the Michigan Wheel that was on her.

------------------
RICKR
mailto:riggerb@aol.comriggerb@aol.com</A>

BigGrizzly
12-18-2000, 07:35 PM
Stick with the Mirage Plus Tom and I swapped props more then you change shoes. He and I both use the Mirage Plus. We have tried many different props and that seemed best out of the box for that motor. We havn't tried the raker yet.

Blewbyu
12-20-2000, 06:50 PM
Second the motion boldts.Well said!