5 blade prop

[vince champion]

Hi i have a 1989 champion with a 1988 mercury 175hp v6 black max engine. The boat came with a highfive stainless steel 5 blade prop. I was wondering what is the purpose of the 5 blade? I think the 5 blade actually slows my mph. My gauge doesnt work (still fixing) so i do not know the exact speed im suppose to be going at WOT. The ex-owner says he can hit 65 mph. When i go WOT i think im doing only about 35 - 40mph slightly faster then my other bass boat which does 35 mph. I do not know how much the champion weigh but my equipment is very minimal. The acceleration is very fast i can plane easily but the top end is slow. How fast do you guys think im suppose to be going? What is the purpose of the 5 blade vs 3blade? thanks in advance. -vince

 

[oops!]

Re: 5 blade prop

uh......i dont know how fast your capable of going...

however....
what you have to be concerned about is rpm at Wide Open Throttle.
the motor should hit max rpm at wot. the max rpm depends on the motor.

if the rpm at wot is not where it should be. that means you are over propped. (means too high a pitch on the prop.. ie...29 inch prop)
if you over rev the motor....your under propped...ie a 13 inch prop.

(inches of prop..ie..29 inch prop..means the distance a prop is said to travel on one compleate revolution. 29 inches of distance..or water moved with one full revolution..)

with a small prop..13 inch, you will scream outta the water fast (get on plane) but your top speed will be low and your rpm very high.
and with a big prop...29 inch..it will take forever to get on plane, but your top speed will be a lot faster. and your wot rpm, lower

the perfect combination is when the max rpm is reached at wot.

each inch of prop you raise, you will loose approx 200 engine rpm.
if your going slow at wot and the engines screeming you need more prop.

the guys on this forum will tell you exactally what rpm your motor should hit.
but im guessing a black max 175 v6 should be doing a lot better than 40mph!

as for the five blade. it is used to get a better hole shot. and to get less prop slip in the water. (prop slip is a totally different thing..but lets call it cavitation) the stainless prop slips less than an alum.

i have heard that the 5 blade increases drag, (after that statement well hear the truth in just a few mins !) but the speed loss your talking about wont be cause by 5 blades vs 3.

hope that helps
cheers
oops

 

[MikDee]

Re: 5 blade prop

A 5 blade has more drag, then a 4blade, which has more drag then a 3 blade, and usually produce less top speed, but the more blades the better hole shot, and acceleration. 3 blade is the accepted norm for most boats, with the best of both worlds. Tell us the prop pitch, & your WOT rpm, for us to help, but 40mph seems slow? by the way, how big is your boat?

 

[oops!]

Re: 5 blade prop

vince... we have very little to go on here. we need more info to help you.
like size of boat. did u do anything to the motor? stuff like that.and also your level of experiance will help to.

but i was thinking...
did you changed anything after you bought the boat?
this speed loss could be somthing as simple as a trim adjustment/engine height, and a few other minor things.

oops

 

[Silvertip]

Re: 5 blade prop

Speed is not of importance at this point but observed wide open throttle RPM and what the prop pitch is are critical. Without those numbers we can be of no help whatsoever. Speed will be whatever you get when a prop is installed that allows the engine to rev in its recommended wide open throttle rpm band. You can tweak speed a little with setup.

 

[vince champion]

Re: 5 blade prop

Thank you everyone for your replies. Sorry i did not reply back earlier hence i was at vegas... Lost over 1000 anyways back to the subject

Oppz... I did not change anything on the boat when bought.

Silvertip... I will get you the WOT rpm range monday. I am going to hit up castaic for some fishing and will get back with some model number of the high five stainless steel. Hopefully you can help me find what kind of High five prop i have and tell me what pitch is my prop at.

Thanks again for all your help. Vince.

 

[oops!]

Re: 5 blade prop

hey vince welcome home!

ya that happens in vegas.

check the angle of attack....

the anti cav plate should be level with the bottom of the hull.

not pointed up or down.
a simple thing like that will cost you huge top end.

happy new year
oops

 

[achris]

Re: 5 blade prop

.... Hopefully you can help me find what kind of High five prop i have and tell me what pitch is my prop at....

The format of the numbers on the prop will tell you the pitch.

The number will be something like this: 47-xxxxxxA47 zzP

The 47-xxxxxA47 is the Merc part number. The zzP is the pitch, in inches. You'll probably find it is an odd number, somewhere between 15P and 27P.

Chris..................

 

[vince champion]

Re: 5 blade prop

Took the boat out monday to castaic and boy it was freezing! winds up to 40 mph so we left and went to puddlingstone lake where it was nice and calm. WOT the boat and found out it hit 5000 rpm with trim down and 5200 to 5300 with trim up just a bit. Now when we got back it was a little late so i decided not to rush and take the prop apart since it is going to be my first time doing so. So i did not get the serial # to the prop. I will get it by this weekend. So without knowing my pitch is 5200 5300 rpm range still low for my engine? or cant tell until i get the pitch? thanks for all your help.

 

[MikDee]

Re: 5 blade prop

IMO, I'd guess your Max rpm should be 5500-6000, that's the usual range for most outboards. Whatever the pitch on your prop is, if you matched it and went to a 4 blade SS you'd probably pick up 2-300rpm & a couple mph, if you went to a 3 blade SS you'd probably pick up 2-300 more rpm, & a couple more mph. A net result going to the 3blade with the same page would probably be 5mph, or maybe more, and 5-600 rpm more putting you right in the upper limit of your rpm range, this is asssuming you run with the same load, extra weight, fuel, gear, people, should still keep you in range with the 3blade. You would rev more with an aluminum 4 blade, or 3blade, but not necessarily gain as much speed because of flex. This is my $.02 good luck, Mike

 

[LubeDude]

Re: 5 blade prop

You have not given it the best test it seems to me. You state that you have " 5000 rpm with trim down and 5200 to 5300 with trim up just a bit". Just a bit dosn't cut it when you are trying to figure WOT RPM. It has to be petal to the metal flat out. It may take a half mile or so to get there also. Bad weather, (Cold) isn't the best time to do this.
If flat out performance isn't what you are looking for and want your boat to be good all around the High Five that you have or a four blade will give that to you. My experience shows me that you are loosing about 5 MPH top end with your High Five, but you can always hire out to pull stumps around in the lake for some extra gas money!!!

If you go ahead and set the boat up for flat our high speed your hole shot will suffer and likely the boat will not be as smooth over all.

 

[vince champion]

Re: 5 blade prop

I appreciate all the information and help. Due to rain and the fact that i dont store the boat at my house it took me a while to get the model # to my prop. The prop model # is 4802822 or 48-81572-23. These 2 number are the only set of numbers i found on my prop. If anyone can please help me find what pitch is on my prop. Again my prop is a high five ss with a 5 blade.
Thanks again vince.

 

[jcsercsa]

Re: 5 blade prop

Hi all , The last two numbers are the pitch, looks like you have a 22 p and a 23 p , hope this helps !! John

 

[vince champion]

Re: 5 blade prop

Thx john, So assuming i have a 23 pitch on a 5 blade stainless steel prop. What should i change if i want more top end? lowering the pitch? Also how much does a 1989 champion bass boat weigh with minimal equipment. As of right now i think i am hitting only 35 to 40 mph. im running on a 176 v6 blk max mercury motor so i should be around the 50's to 60's mph correct? something is wrong here so im trying to get the most out of my engine. Thanks again vince.

 

[jay_merrill]

Re: 5 blade prop

If speed is what you want, get rid of the five blade prop and go to a three blade. If you can find a two blade, theoretically, that would be even better.

 

[jcsercsa]

Re: 5 blade prop

Yea I agree go to a 3 blade , if you do you will lose a lot of your hole shot !!! John

 

[vince champion]

Re: 5 blade prop

So if i go with a 3blade should i stay with the same 23 pitch? What would be the best set up?

 

[jay_merrill]

Re: 5 blade prop

Make your decision on pitch based upon your rpm range at WOT. You motor will have a minimum rpm that is acceptable at WOT and a maximum number. If you are at or near maxium safe rpm at WOT with the 23" wheel, go up one increment. With some manufacturers, that will be a 25" wheel but you may find a 24" that works on your motor. Depending on where you buy the prop, the dealer may even let you try one out, especially if they have a used version of what you think you want, before comitting to the purchase of a new one.

If you are having to back the throttle off to stay within maximum recommeded rpm, you will have that much more "room" in terms of using a higher pitch. Generally speaking, each inch of pitch increase will reduce engine rpm at WOT by about 200 rpm. Bear in mind, however, that you will probably gain about 100 rpm just by going from a 23", five blade prop to a 23", three blade prop.

When deciding how far to advance in pitch, keep your typical load in mind. For example, if you went to a 25" prop and found yourself running a couple of hundred rpm below maximum recommended rpm at WOT, but you were alone in the boat, that prop might not work well if you often load the boat up. In that case, you might want to stay at 23" or go to 24", either by finding a prop at that pitch or by sending yours to a prop shop to have it "pitched up."

Hope this helps!

 

[Chris1956]

Re: 5 blade prop

Vince, The RPM numbers you indicate show that your prop is very slightly over pitched. However, with those numbers, you should be near to your top speed, even with the 5 blade prop. I will assume you have some sort of Bassboat, maybe 18' long? The prop is in good shape, correct?

You need to check your speed with a GPS, for accuracy. I would think you should be hitting 45+ MPH with that rig, since the propeller calculator shows you have (at 40MPH) about 30% slip, which would be very unusual.

if you indeed have that much prop slip, you are either ventilating the prop, or something on the boat is dragging. Do you have a 25" leg motor on a 20" transom?

You do remove the trailer from under the boat, before fishing, right (That's a joke)!