Merc 5-blade vs. Merc 4-blade
 

What pitch size do you move to for moving from a 4-blade to a 5-blade? Also, would a Formula Fastech 382 benifit at all from this change....or would it just look cool?

Thanks!

Re: Merc 5-blade vs. Merc 4-blade
 

Typically you will decrease one inch of pitch, but the Maximus is different. There are many variables such as its large diameter if stock. The normal pitch theories do not apply. Comparing a 32P Bravo I to a 32P Maximus you would to experience and RPM decrease of about 500-600 RPM. So you would need to drop pitch or reduce diameter when re-propping.

Julie

Re: Merc 5-blade vs. Merc 4-blade
 

Depending on the rpm you run with the 4bl and what you are looking for with the 5bl would determine the decrease in pitch. Plan on at least 2".

Decreasing the diameter of the Maximus isn't always necessary. If fact diameter is good if the boat can handle it. Meaning attitude of running surface, rpm, and most importantly what gear case you have. The prop will not hit every gear case.

As far as harder to Lab Finish, we Lab propellers different for certain applications. We don't find reducing diameter in the Labbing process to be a deterrent or more difficult.

Your rigs benefited would come in certain areas but possibly not in others. We would need to discuss your current numbers through the rpm range.

Re: Merc 5-blade vs. Merc 4-blade
 

Has anyone compared a hydro 5 blade to the new 5 blade Maximus on the same boat? I am thinking of going to a hydro 5 blade on a 280 Velocity with a higher X than normal and looking at my options.

Re: Merc 5-blade vs. Merc 4-blade
 

Interesting info.....but is there anything to gain going from 4 to 5? Is more better? That's basically my question. Geez Troutly, didn't you read my post!!! :) :D :D :D

Re: Merc 5-blade vs. Merc 4-blade
 

Yes, we have tried both the Hydromotive P5-X and the Maximus 5B on the same boat. The Maximus was much slower than the Hdyromotive. The Maximus did produce an increase in cruise as did the Hydro P5-X. We then labbed a Maximus and ran it again agianst the P5-X the speeds were much better for the Maximus. From our experiences the the Stock Hydro P5-X runs similar to that of a Lab Finished Maximus. So the choice is personal and financial for some. Now as far as gain when going from a 4B to a 5B the improvements are similar to that of when you went from a 3B to a 4B. You will have better hole shot, increased acceleration, increases in cruise speeds, improved perfromance and handling and less slip. Keeping in mind that slip translates into speed! Now as far as top end is concerned you may see increases, run the same or possibly lose 1-2 MPH on top. This is really a question as to how well the boat is currently dialed in. For example if you are currently running a 4B at 15% or so then it is possible that running a 5B at 9%-10% at the same RPM can possibly lead to net increases in top end or equal speeds with no speed loss, in which case pitch would be a variable. Hope this answers your question.

Julie

Re: Merc 5-blade vs. Merc 4-blade
 

Each and every identical application is different. I've seen the Labbed Maximus blow the doors off the stock P5-X. The P5-X needs a boat that flys it's bow on its own.

It's hard to make general consensus as to what will happen with all applications. Decreasing slip due to more blades doen't always happen because you have more drag from additional metal in the water. Also, more stern lift could affect the wetted surface area of the boat also increasing drag and slip.

Some of the generalizations made here I would agree with. More blades=better holeshot, handling, and mid range.
But,,,,only if the correct pitch is used and only up to certain rpms.

Don't get me wrong, 5 and 6 blade props are awesome on the right boat and set up. Race boats with high X's love them on rough water and short courses. They just aren't a cure all to the general boating public. Test, test, test. Seat time, seat time, seat time.

Re: Merc 5-blade vs. Merc 4-blade
 

I would have to disagree with you. The P5X has a rake angle similar to a Bravo 1. We have found that it has the ability to carry the bow.

Matt

Re: Merc 5-blade vs. Merc 4-blade
 

No matter how much you rework a multi bladed propeller, more blades means more stern lift. Yes you can reduce diameter to settle the back down. But at some point the diameter reduction with destroy the geometry of the propeller and it won't do what it was intended to do.

Yes, as far as bow lifting 5bl's are concerned, the P5-X is round eared and does have some bow lift built in. No cut intended to the propeller. The fact remains, if you continue to lift the stern, there is less ability for the arm length to get the leverage to raise the bow. Therefore, high X, flat running, or C.G. adjusted boat can prosper from 5Bl props. Likewise, boats not needing bow lift will do well with this prop.

But, if you truly need more bow lift, this prop may not be the right choice.

Re: Merc 5-blade vs. Merc 4-blade
 

Carry the bow on what boats?

The rake on a Bravo 1 is only considered to be medium in degrees. It is also only a 4BL. You can't compare the two. Also, the Bravo 1 isn't concidered a huge bow lifting propeller anyway, although better than a Quad-4 or other 4blades.

The rake angle on the Maximus is actually higher than the Bravo 1. That would also make its rake higher than the P5-X giving it more bow carrying ability than the Hydromotive.

I guess we'll have to agree to diagree on this one.

Re: Merc 5-blade vs. Merc 4-blade
 

The rake angle of a P5X is about .5 degrees less than a Maximus.

Re: Merc 5-blade vs. Merc 4-blade
 

Norty,, Troutly,,, :D :D Just how hard do you Guys want those Blades to Hook Up??? How tuff are your Bravos ,,, I believe that if ya get down to that 8-10% slip factor ,, with your heavy boats ,,,, then your gonna get broken bravos,,, I think the 4 Blades work fine ,,, I want to go boating , not , to the trailor for repairs!! :drink: :drink

RHC

Re: Merc 5-blade vs. Merc 4-blade
 

Let me get this strait, you agree the maximus has the most natural bow lift.(I think) If so, how do you increase the bow lift further?

Also what is the target slip % on the maximus? I can run mine anywhere from 9-15% depending on drive height. I have not been able to run over 80% throttle due to conditions, so I don't know what will be faster yet.

Re: Merc 5-blade vs. Merc 4-blade
 

zt260,
The rake angle of the Maximus, Bravo 1, P5X, and Quad IV X is basically the same. Being production props the rake, pitch, diameter, progression and cup will vary from prop to prop.

The diameter of a stock Maximus is about 15 3/4", even though it's marked 15 5/8". This large diameter will lift the stern thus causing greater stern lift. Of course all these props can be modified to change their lifting characteristics.

As far as slip there are several factors that will effect it. What type of boat and power do you have? More bow lift is not always better.

Matt

Matt

Re: Merc 5-blade vs. Merc 4-blade
 

RHC,

More blades does not necessarily mean broken drives. We have found that more blades can mean less drive failure. Because a 5 or 6 blade prop is smoother than a 4 blade there is less vibration and stress on the prop shaft, especially in high drive height applications. Of course if you are talking about launching the boat there would be a greater loading of the drive upon landing if the throttles are not pulled back. In water conditions where the boat is not able to stay hooked up with a 4 blade a 5 or 6 blade prop may stay hooked up to the water thus causing less stress to the drive line.
Every application is different and each propeller design has it's advantages and disadvantages. It's just a matter of getting the prop that works best for your style of boating, whatever that may be.

Matt

Re: Merc 5-blade vs. Merc 4-blade
 

The boat is a 26’ Checkmate with 1300HP and a 1.3 ratio Bmax. My current X-dim is 15 ½”, slip is at 14%. I don't want to decrease the diameter, since I'm really starting to surface pierce this prop. What can be done to add bow lift to the 26" maximus? Specifics about the labbing process you recommend would be helpful in making a decision. I'm sure you know, but most checkmate love bow lift and mine is no exception.

Re: Merc 5-blade vs. Merc 4-blade
 

In a vee hull, where does turning the props in vs. out play in the bow lift equation? (assume side by side engines) Does turning the props in cancel out some or all props natural stern lifting design?
Where does the Herring 5-blade line up in the comparison of the Mercury and Hydromotive 5-blades as related to top speed?

Re: Merc 5-blade vs. Merc 4-blade
 

I was with Mercury Racing during the development of the Maximus propeller.

Our original geometry we suggested was to have the prop built at 15.25" diameter. During the final stages of development, the main plant propeller Co. adjusted the print. The resulting propeller became 15 5/8".

This was not necssarily a bad thing because the additional diameter would work on some applications. But only SOME. Why do you think Mercury offers 3 different diameters in the Lab versions. They do this because additional diameter lifts the stern too much and can't be spun by alot of Bravo, BMax, IMCO drive boats due to seaking the surface. Sure it can be spun high and vented, but will this carry your bow? Maybe.

We also made the prop with a high degree of rake. The reason was because 5 blade propellers are notorious for stern lift, not bow lift. We needed to assist it holding the stern in place. Again, with the right application the Maximus kicks butt.

zt260, Oh yeah do Checkmates need bow lift! We typically wouldn't suggest a Maximus for your application.

B P, in vs. out has some basic concepts. Rotating in will create bow lift on V's most of the time. It will hamper idle in gear operation though. Some manufacturers hulls actually perform differently and actually oposite to the therory. We did alot of development with Jay Pilini from Spectre and his boats have a different reaction.

Every application even if identical is different!!

TEST TEST TEST

Re: Merc 5-blade vs. Merc 4-blade
 

I would love to try a 5 blade because of my high slip #'s. and X dimension. The boat is an 05 single stepped, notched transom, w/ a pad, sunsation 288 w/ 496 H.O. Current speed and slip #'s are as follows:

26 Bravo 1 = 5,100 @ 69-70 mph 17.5 % slip
28 Bravo 1 = 4,800 @ 69-70 mph 18 % slip

Midrange @ 3,500 is around 47 MPH and @ 4,000 is around 55..
Holeshot is o.k.

If I can find the correct 5 blade, I should, in theory, increase holeshot, increase midrange, and hopefully decrease the slip to around 12 % and therefore increase top end as well,,, O.K. Prop GURU's ,, who's got a prop for me to try ???

Re: Merc 5-blade vs. Merc 4-blade
 

I would try any properly pitched 5 blade I could get my hands on. You should drop a lot of slip.

Re: Merc 5-blade vs. Merc 4-blade
 

Chris288,

Keep in mind that when you run your slip numbers with a Bravo I propeller you need to reduce the pitch one inch from what is actually marked on the propeller. Bravo I propellers are not true to pitch so your 26P is really a 25P. Thsi gives you a slip of 13% not 17%. So it looks like your drive heigth is good and I would recommend a Hydro P5-X on your boat in a 25P. Hope this helps!

Julie

Re: Merc 5-blade vs. Merc 4-blade
 

Keep in mind that we have a Prop Fitting Program that is always availabe to you for testing!

Julie

Re: Merc 5-blade vs. Merc 4-blade
 

This stuff is really a science!!

Re: Merc 5-blade vs. Merc 4-blade
 

Thanks for the suggestion and info Julie,, if I run my #'s again using 25 and 27 I get a slip of 14 for the 26 and 15 for the 28... What are your feelings regarding giving a stock 27 p5x a shot and see what my numbers are and then have it labbed for extra rpm from there ??,, obviously if I'm looking into a 5 blade, holeshot, and midrange should be a given,, and at that point I'd be interested in top end only.. ?? Thanks Chris

Re: Merc 5-blade vs. Merc 4-blade
 

You could try the 27 but I think you will need something in the 25 pitch range with a 5 blade prop. The 27 would be a little low on rpm but you would get an idea how the boat handles with the prop. We are going to add a 25 to our test props. We should know by Monday.

The 25 should put you right at 5000 which is where we want the 496 HO to run for max speed. It's possible to pick up a little top end with the 5 blade prop for your application. I think it should do that right out of the box. After looking at your numbers we could look into lab finishing the prop, if necessary.

Matt

Re: Merc 5-blade vs. Merc 4-blade
 

back to the original question here is my results,Formula 382 f2 race boat not as heavy in bow as yours. merc bravo 1 4 blade labbed 32", 26% slip.I could not get the boat to respond to trim at all.Then I put a pair of p5 hydro's 30"( non labbed) on and slip went down to 10% The boat responds unbelievable to trim I can lift the bow as high as I want even at lower speeds, and at wot it lifted the whole boat at higher speeds and never lost any top speed.I gained 7mph at 4000 rpm when cruising.Please remember my boat is set up different ,my x dimension is 2.5" higher than my buddies 382 formula and weighs 3000 lbs less.I would go with the maximus or p5x to help carry the bow.You will love how the hold the water, less slip.

Re: Merc 5-blade vs. Merc 4-blade
 

Thanks Matt,,,,,,, If a stock 25 would put me at 5,000, thats why I thought a 27 would be a better place to start,, I know it would be down on R's,, but then wouldn't the labbing bring it back into range ???? And then if I end up adding the Raylar heads to boost the H.O. from 425 to around 475-500 hp, I should still have enough prop ??.. Thanks again..

P.S. I would be interested in giving that 25 a shot if you end up adding it..

Re: Merc 5-blade vs. Merc 4-blade
 

Something important to keep in mind is if you put the Raylar heads on at what rpm does it produce the 475hp? If the heads move the hp up the powerband then you not need the taller pitch. The lower pitch may do it with an increase in rpm.

When we lab finish the P5X we don't see rpm increases like we do with Bravo 1's. The P5X will usually pick up about 150 rpm from a lab finish which is about 1 inch of pitch.

Matt

Re: Merc 5-blade vs. Merc 4-blade
 

Brett and Matt: Any comments about the use of Bravo, Maximus, P5 and P5X on cats running over 100 mph? I have been reading this and other threads about 4 vs 5 blades and my limited understanding would be that cats don't need any bow lift from the propeller.

Re: Merc 5-blade vs. Merc 4-blade
 

Troutly, yes I did and a response will be coming back asap.

tomcat, my responses were trying to explain the differences in multi bladed propellers versus propellers with less blades. Because certain propeller geometries induce stern lift, a boat not capable of carrying its bow may have issues running a 4,5, or 6 blade prop. It's like comparing a cleaver to a chopper. One carries the stern while the other carries the bow. As a propeller approaches the surface, it has less water to leverage itself against. The result is allowing the bow to drop. Some cat boats as well as vented v's don't need the bow lift because they pack air in the tunnel or ride on very aerated water.

This being said means in no way that a 5 or 6 blade won't work on your boat whatever it is. It just means the laws of physics show the more blades and or diameter will induce tail lift. If your rig can handle that, and the trim ability the specific multi bladed prop has built into it, you will most likely love the benefits they offer.

We know from testing and feedback, some of the boats that do and don't like them.

One cat known as a Hustler formally as a Talon, needs bow lift. It's one of those boats that just has its own personality. It is a awesome boat and in race configuration hauls a$$. But in a standard lay up and CG, it needs the correct propeller and rotation.

Multi bladed propellers came in to existence for certain applications, not all of them.

I hope this helps a little.

Re: Merc 5-blade vs. Merc 4-blade
 

Tomcat,
As a general rule cats don't need bow lift, in fact many of them attain max speed with negative trim. That's why they typically respond well to multi blade props. The Bravo 1 prop is the most versatile prop on the market in that it will work respectably well on just about anything that floats. It may not be the best prop for an application but it will work. The Bravo 1 has proven to work well on cats but usually at the expense of getting on plane well and without the acceleration a multi blade prop can offer.

The only way to find out what is the best fit for your boat and style of boating is to try different props. Two identical boats but owned by two different people may have different props on them due to the different style or driving and the type of boating they do.

We will do some testing this weekend in Ft. Lauderdale with a cat and P5X's. In this case we are trying to settle the stern down caused by large diameter 6 blade props.

Matt

Re: Merc 5-blade vs. Merc 4-blade
 

Brett: Thanks for answering. I hear what you are saying about multi blades being a fix for something else, like excessive drive heights. From my own experience I know that adding a blade just slowed the boat down until I also raised the drive. This gave the best speed but even with the extra blade did not have has much bow trimming ability as less blades deeper in the water. This was in a test of Mirage Plus vs. Bravo with and w/o 2" spacer.

Matt: Thanks for answering, if you can tell some specifics of the cat with the six blades. When the stern is lifted too much are you concerned only about handling or does the bow drop in reaction and cause slower speeds?

Re: Merc 5-blade vs. Merc 4-blade
 

Troutly,

I sent it last night at about 7:30. Must of been too long again and didn't go through. I'll rewrite.

Re: Merc 5-blade vs. Merc 4-blade
 

Matt,, did you end up getting a 25p P5-X that I could try ??? Thanks Chris..

Re: Merc 5-blade vs. Merc 4-blade
 

tomcat,

We have yet to have a cat lose speed with a 6 blade. We have 6 blade props on everything from 28 Eliminators to DCB's to Skaters, Spectres, ect. Some have big power and some are stock 525's. Some are running over 150 mph. Some have slip as low as 3.5%. We have not had any issues with excessive stern lift with any of the cats as well as any of the V bottoms that run our 6 blade props. Including those that typically like bow lift. The prop can be worked to reduce the amount of stern lift, if there may be a problem with that.

We have had outstanding success with the 6 blades on many single engine v bottoms. Including the Super V Lite class race boats.

It's more likely for a cat to lose speed when the stern is dropped with too little stern lift. The air in the tunnel can not escape thus slowing the boat down.

Before we sell a six blade prop we try to make sure the customer's boat runs well with it and make sure the 6 blade prop will meet his goals.

Matt

Re: Merc 5-blade vs. Merc 4-blade
 

troutly,

Please email me so I have your email address. My message was too long again and I don't want to condense it.
[email protected]

Cats definately like stern lift as a general rule. They are like an airplane wing and must fly flat. We have found some cats that don't need as much as others. We cut diffusers off some surfacing props on some cats to decrease the lift.

Of course if you pack too much air in the front of the tunnel, from not enough tail lift, it's like a wall and the cat actually porpoises.

It's hard to compare a race boat with a standard lay up pleasure boat that has the CG in front of the helm. Especially V's.

There is no reason to defend the 6BL propellers. When they work, they are awesome. As pointed out before, High power, high X dimesions like a larger diameter shorter deration from load to unload type of propeller. That's why cat's and race set ups love them. Not 36 Baja's.

Are we repeating ourselves here?

If you get the chance to try any propeller on your boat........do it! You must decide what works best for you.

also looking to see what works?
 

I have an 07 25' shockwave and am looking for any advise that could be given on what prop works best? is there any one out there that could help me out? i have instaled Dana Marine headers and have a 496ho. I am looking for top end as it seem that the motor has all kinds of mid range.

The largest pitch 4 blade propeller Labbed to get into the upper end of your desired rpm range should give you the best overall performance as well at top speed as long as we end up in the 9-13% slip range.

so i was thinkng a brovo 1 26?? what about a maximus 5 26? boat has great bow lift already and X dimension is about 2'' up im new to this and trying to understand everything that goes into it. thanks again.

Here are some numbers from some testing I've done with three different props. As you can see the lower-range with my boat really improved with the larger diameter Maximus.
http://www.performanceboats.com/html.../500/graph.jpg