Cleavers VS surfacing.

[Techno]

While doing all the searching and crap for the electric prop idea I found out that there really isn't any reason to run cleaver props on a surfacing rig.
The whole point of a cleaver is to prevent cavitation and a surfacing prop of any kind prevents this since its air entrained from passing through the air.

A cleaver is mostly meant to run submerged, since almost no one is running them submerged whats the point in using one?

I'm not talking bow lift/stern lift issues since this can be done by other blade items. A cleaver is a sharp edged blade ending in a square shape. This isn't the ideal blade shape for propelling water. It also seems from the STV site that not many have had as good performance from them and I'm beginning to see why. Its a high performance highly loaded submerged propellor design running in lightly loaded surfaced conditions.

Also found out, or refound out, relearned. There is no such thing as a 26" prop pitch, or any other prop pitch you can definately use as a comparision. This is even true with the same maker. Its most definately true with comparing one maker with the other. Props are far too complex to be able to say this prop is pitched at what ever pitch. This is one reason why prop slip changes so dramaticly while comparing many props. It is just as likely the prop pitch is different and the slip is the same.
Just by changing the blade shape with all the same angles you can change its pitch. By blade shape I'm only talking of its sillohette not cupping.
Is the pitch at 70% or is it at 76% or what?

[Euroski]

What he said.... Wouldn't it be great if someone designed a prop with the properties of a ET & cleaver all-in-one. That way you would have the quick take of up to about 70mph and then the cleaver properties would take over to handle the top end mph? also there was a world of difference on my STV when comparing a stock cleaver vs the lab cleaver.

[msm]

What's the electric prop idea?

[stokernick]

since when is a cleaver supposed to run submerged?The surfacing blades give you stern lift and higher rpm's the last I knew!

[Alan Power]

A cleaver is whats known in propellor design as a super cavitating propellor, ie, it's designed to run on the surface or be vented (aerated).

[pyro]

The wedge blade profile is key to the cleaver's design. The blade is like a wedge entering the water. Almost as if the face and backside of the blade have different pitch. It has a "lift" as a side effect.

[Trikki1010]

It also seems from the STV site that not many have had as good performance from them and I'm beginning to see why.

I couldn't disagree more Techno

I've run my FASTEST w/ a cleaver, into the 120's w/ a "stock" 280 on a 95 Euro

Helmut has run his fasted w/ a 32" lab cleaver

What did Dixon run on his Speedmasters, what do Champs run????
There ain't a chopper OR ET in their inventory of fast runs;)

Maybe on a little electric boat, mine tended to wonder a bit much with the larger PADDLES;) :eek:

[Techno]

http://en.wikipedia.org/wiki/Supercavitating_propeller
Check this out then splain to me???

I should add that when I say performance this isn't a word that means top speed or fastest hole shot. Its performance. how well does the cleaver perform since I seem to remember just about everyone saying that the cleaver isn't as nice to drive?

[pyro]

The wedge shaped blade is slinging thrust water faster than it's "inhaling" the next bite of water. Splits the water like a wedge.

[Trikki1010]

Check this out then splain to me???

This is the text to ur link
The supercavitating propeller is a variant of a propeller for propulsion in water, where cavitation (formation of water vapour) is actively employed to gain increased speed by reduced friction. The supercavitating propeller is being used for military purposes and for high performance boat racing vessels as well as model boat racing.

The supercavitating propeller operates in the conventional submerged mode, with the entire diameter of the blade below the water line. The blades of a supercavitating propeller are wedge shaped to force cavitation at the leading edge and avoid water skin friction along the whole forward face. The cavity collapses well behind the blade, which is the reason the supercavitation principle avoids the erosion damage due to cavitation that is a problem with conventional propellers.

An alternative to the supercavitating propeller is the surface piercing, or ventilated propeller. These propellers are designed to intentionally cleave the water and entrain atmospheric air to fill the void, which means that the resulting gas layer surrounding the propeller blade consists of air instead of water vapour. Less energy is thus used, and the surface piercing propeller generally enjoys lower drag than the supercavitating principle. The surface piercing propeller also has wedge shaped blades, and propellers may be designed that can operate in both supercavitating and surface piercing mode.

The pioneer of this technology and other high speed offshore boating technologies was Albert Hickman (1877-1957), early in the 20th century. His Sea Sled designs used a surface piercing propeller.

I think I'll fall under the latter catagory (variation;) )and will stick to my guns. We don't run fully submerged applications to reduce drag from the bullet being submerged.

Techno, I'm always open to new ideas and ways of doing things, I just haven't seen justification of that application in our genre;) :D

[Techno]

How much speed increase and how much handling diff is there between a cleaver and others?

BTW I am not saying to run cleavers on our boats submerged. I'm saying this is what they were designed for, not on our boats but for heavily loaded props I doubt anyone is running a heavily loaded cleaver prop on an OB.

[Trikki1010]

How much speed increase and how much handling diff is there between a cleaver and others?

BTW I am not saying to run cleavers on our boats submerged. I'm saying this is what they were designed for, not on our boats but for heavily loaded props I doubt anyone is running a heavily loaded cleaver prop on an OB.

I figured that after I read the whole article, BUT being somewhat of a wisearse:rolleyes: , AND the fact we haven't seen ya in a while;) I didn't want to show ya any favoritism:eek: ;) :D

[stvhelm]

Also found out, or refound out, relearned. There is no such thing as a 26" prop pitch, or any other prop pitch you can definately use as a comparision. This is even true with the same maker. Its most definately true with comparing one maker with the other. Props are far too complex to be able to say this prop is pitched at what ever pitch. This is one reason why prop slip changes so dramaticly while comparing many props. It is just as likely the prop pitch is different and the slip is the same.
Just by changing the blade shape with all the same angles you can change its pitch. By blade shape I'm only talking of its sillohette not cupping.
Is the pitch at 70% or is it at 76% or what?

From what I undertstand pitch is measured by how far a prop will travel in 1 revolution. A 26p prop goes 26" in 1 turn. I believe all prop manufacturers use this rule. ofcourse altering the blades can effect its pitch. By putting a propeller on a long shaft and turning it through a tank of gel or jello you can easily measure and determine the pitch. new technology has made it possible to accurately measure and match propellers and Im sure high end prop manufacturers are already at it.
check this out. maybe you build your own;) http://www.australpropeller.com.au/propscantech.htm

[hydroholic]

http://en.wikipedia.org/wiki/Supercavitating_propeller
Check this out then splain to me???

I should add that when I say performance this isn't a word that means top speed or fastest hole shot. Its performance. how well does the cleaver perform since I seem to remember just about everyone saying that the cleaver isn't as nice to drive?Not arguing with your train of thought,but for me it is the oposite.My boat turns easier at all trim angles and all speeds,tracks straighter and I have ran my fastest speed with a cleaver and I do run it surfaced.I also have a chop in the same pitch and diameter that I sometimes run (if I am pulling a tube or skier) and it is harder to turn and produces more more chine walk and is quite a bit slower than the cleaver and won't turn near the rpms.Just my experience with my rig.Not saying you are wrong.Hydro

[Techno]

From what I undertstand pitch is measured by how far a prop will travel in 1 revolution. A 26p prop goes 26" in 1 turn. I believe all prop manufacturers use this rule. ofcourse altering the blades can effect its pitch. By putting a propeller on a long shaft and turning it through a tank of gel or jello you can easily measure and determine the pitch. new technology has made it possible to accurately measure and match propellers and Im sure high end prop manufacturers are already at it.
check this out. maybe you build your own;) http://www.australpropeller.com.au/propscantech.htm

Very few companies sell you an accurate prop. This is why merc sells labbed props because the box props are sorta close enough for most people. Even a labbed prop could be labeled as the wrong pitch because they measure it at one spot and your boat uses another spot. This is the thing. You can't math it out. You can make a specific pitched prop but this is a chosen distance and it might not be what the prop produces in the real world.
They measure props at a certain percentage of blade length. Different styles produce thrust at different spots. Same props provide thrust at different spots on different boats. Its as if the pitch changed, which it actually did.
Stamped as a 26" you used it as a 25" and a buddy used it as a 27" The difference is figured as prop slip but you used the wrong pitch to calculate slip. It was measured at 75%, you used it at 72% and your buddy was 78%.
This gets worse when you compare a chopper with a cleaver They aren't measured in the same blade length spot so could give different readings than what the pitches claim.
What I'm saying is this is the reason to test test test, borrow, borrow borrow.

hydroholic Thats what I mean by performance, what'd you do polish it so much its a chopper.:) You probably rounded of the corners.:eek:

[SportJ-US-1]

Actually all high performance props blades are not a constant pitch thru the blade. They can have as much as 4" or more of pitch change. Be 24 pitch at the leading edge and 28 at the trailing edge, for example. So they average the pitch to give you a number. But different props labeled 26, may be totally different in the amount of change and how fast the pitch changes happens. You guys are trying to make something very complicated into something very simple. Can't be done.

[Yamaha 70 c]

Techno, the article you found on propellers describes two quite different principles don`t you agree? The first one being the supercavitating prop for submerged prop, which creates cavitation to reduce drag. The second one is the surfacing, vented principle that we recognize as the cleaver. So in my ears it doesnt seem right to say that the cleaver is designed to be submerged, it`s designed to be vented by surface piercing.

Totally agree with you on the pitch, it varies depending on how much of the blades you put into the water. Can`t figure out or measure no magic number, anything would be either an average, or a spesific number for a spesific radius.

From what experience I have with performance boats I must say that its often more fun to drive with a chopper. But, in races I tend to get much better results with cleavers, at least if it gives about the same topspeed. Cornering and punching through wakes is much better with cleavers is my experience, and so your average will increase. So if your racing, Ì`d say cleaver is the best fun, because getting there first is whats fun in a race!

[Techno]

Yamaha 70 c
The cleavers wedge shaped blades are meant to shed cavitation surrounded by water, no air. The surfacing prop doesn't need to shed cavitation since there isn't any. So I have to wonder why run a prop that sheds cavitation in a condition that doesn't need to shed the cavitation that doesn't happen?:confused: That sentence even confused me!


What SportJ-US-1 said about they are too complicated to simplify could include cleavers in my all encompassing remarks about them. But since he also agreed that they sucked I will use his testimony :D since he had what amounts to a prop shop hanging props on his boat................and he agreed with me.:D

I'm mostly saying when you try a prop and its stamped with a pitch number you can almost ignore this as far as comparing to another prop. Instead of prop 1 being a 28" its an A and instead of the other prop, whatever its style, being a 30" its a B. You can't measure A or B. You can compare them and wonder why A works so much better than B even though B should go faster. But you can't say the 28" slipped this much or should go faster with a 30" because these are letters.:confused: I think I may have gone too obtuse there.
Instead think of them like dragster tires. What diameter is a dragster tire?

Really all that I've said explains why you test any prop that comes your way. It don't make sense but if the props weren't stamped then it would.
Hell- even test a cleaver it if comes your way.:eek:

[pyro]

Running on the surface, the wedge-shaped blade entering the water also has a stern-lifting effect, which is another reason, a big reason, that people use them on some boats.

[eli]

cleavers are not ment to run deep ,i tried it DONT WORK! mine are more than half out of the water at speed,round ears go deep and handle worse,hole shot is better with a deep cleaver. round ears handle like crap surfaced especially on a twin setup. and is hard on lowers. my 2c

[Jimboat]

...very interesting discussion...good comments by all of you guys.

The "Pitch" definition is one that often gets confusing. I am in agreement with Helmut when he describes the pitch as "how far a prop will travel in 1 revolution"....This is exactly right! It also leads to the discussion about "theoretical pitch" versus "real pitch"....the former being the distance the prop would travel based on it's true dimensional pitch; the latter being the distance that the propeller actually travels when rotated. These are almost always not the same, due to the environment that the prop operates in, and other influencing factors such as rake, skew, cup, etc.

What SportJ-US-1 said about the whole issue being very complicated is probably the best comment at all....it really is.

sure is an interesting thread, though!

[staylor]

...I've seen cleaver style props work extremely well on all kinds of applications, both surfacing and submerged. They seem to work best on rigs that want stern lift, or at least less bow lift than a chopper. There is a definite gray area between cleaver and chopper style blades on today's props- the Tempest Plus being a good example, having a blade shape that's got a bit of both styles mixed together, and a blade cross section that is distinctly cleaver like, terminating in a very thick trailing edge and cup.

As for the current progressive pitch designs on many props, none of the old rules apply very well. You can list an average pitch, but this is just a wild guess. To make it even more interesting, you can switch a given prop between 2 different boats and the lighter boat will seem to run on the higher pitched end of the pitch progression, the heavier boat will appear to run on the lower pitched end. This is much different than the old theory of just putting the prop into a tub of grease and turning it one rev to see how far it moves- and makes picking the "right" prop much more difficult.
Doug

[vector mike]

...To make it even more interesting, you can switch a given prop between 2 different boats and the lighter boat will seem to run on the higher pitched end of the pitch progression, the heavier boat will appear to run on the lower pitched end.
Wouldn't that be refering to slip?

[staylor]

...I've tried swapping older style props with a constant pitch between boats with much different results- and on these older props slip is an issue. In one case I swapped a 21 aluminum prop between 2 rigs with about a 30% weight and size difference- and the 21 was over-revving on the lighter boat. I did the same thing with a 21 Trophy Plus, which ran the same rpm as the aluminum on the heavy boat- but the light boat no longer over-revved, and picked up 3 mph. Thus, I think it's more than just slip.
Doug

[pyro]

It's only considered slip if you truly consider the prop to have one definite pitch.

[Magcat 62]

Round ears handle like crap surfaced? give me a break i guess 10 thousand chopper owners are using the wrong prop.

[Magcat 62]

i always thought of a pool of jello! LOL.

[Magcat 62]

Not arguing with your train of thought,but for me it is the oposite.My boat turns easier at all trim angles and all speeds,tracks straighter and I have ran my fastest speed with a cleaver and I do run it surfaced.I also have a chop in the same pitch and diameter that I sometimes run (if I am pulling a tube or skier) and it is harder to turn and produces more more chine walk and is quite a bit slower than the cleaver and won't turn near the rpms.Just my experience with my rig.Not saying you are wrong.Hydro My rig cant run a cleaver period reasons unknown over revs wont hook have to run chopper with torque tab boat combos set-up huge difference for sure good post. my new scorpion is best prop yet minimum torque super lift all around . just would to get the bobs cone off i think its slowing me down it seems every motor i get has has a bobs L\W I HAVE 1 stock but its a 2-1 gear

[eli]

Round ears handle like crap surfaced? give me a break i guess 10 thousand chopper owners are using the wrong prop. compared to cleaver round ears like choppers have more steering torque ,vibrate more and on my 23 daytona were absolutely terrible trying to go to top end too much bow lift had to run neg trim which made things worse ,i run choppers on the twister for short runs to 100 at events then back to cleavers for every day cruising .

[Magcat 62]

1 QUESTION why everyone blames chine-walk on the prop? i think hull-pad design should share the blame also i guess its easier to blame prop than to change the boat mold just TOL

[Mark75H]

1 QUESTION why everyone blames chine-walk on the prop? i think hull-pad design should share the blame also i guess its easier to blame prop than to change the boat mold just TOL

Because the prop lifts the boat completely out of the water ... unless you are running a tunnel, the hull-pad can't do that

[Magcat 62]

[QUOTE=Techno;1013350]Yamaha 70 c
The cleavers wedge shaped blades are meant to shed cavitation surrounded by water, no air. The surfacing prop doesn't need to shed cavitation since there isn't any. So I have to wonder why run a prop that sheds cavitation in a condition that doesn't need to shed the cavitation that doesn't happen?:confused: That sentence even confused me! YEAH HOW HIGH IS UP????? SURFACING only purpose is to reduce drag and still keep slip to a minimnum IMO the chopper and scorpion have mastered this scorpion best yet im at about 5-7% slip surfaced. smooth too!!!! art

[Magcat 62]

wouldnt you think a slightly inverted v pad would help with rocking motion like the old concave water ski?

[Baja170]

I am running a pair of 30P cleavers on CLE's on my Shadow and I have tried a few sets of other props. Come for a ride and see if they work. -1 or more X factor on a 21 Linder Shadow, not a cat although pad has been eliminated and hull has been blueprinted.