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.