Prop question

[Genjem]

I currently have a mirage 3 blade ss 21 pitch blade on my boat. Boat is 1993 18ft celebrity with 4.3lx. Wanting to go 4 blade to get more hole shot. Do I need ss or is aluminum ok?

 

[alldodge]

Re: Prop question

Guess Bondo-o will be along shortly to move this to the prop section, but...
Opinion: I don't see a 4 blade getting you more hole shot, it will give you more lift which can be bad overall. The boat is lifted higher which makes handeling a problem because the boat is a bit heavy. The true prop guru should be able to provide more then I.

 

[QC]

Re: Prop question

Moved to prop section.

 

[QC]

Re: Prop question

Genjem,

Take a read of the stickies at the top here. That will help some with your question. Good luck, and welcome aboard!

 

[Tail_Gunner]

Re: Prop question

The prop you have now is one of the best, To get any kind of good input you should follow the below


ESSENTIAL DATA REQUIRED
When posting a question about propellers, you cannot get a reasonable answer unless you provide the following information in your post: Items 1-4 are essential for meaningful response to most questions.
1) Performance issue you are trying to correct.
2) Current prop manufacturer, model, aluminum or stainless as a minimum.
3) Current prop diameter and pitch (required).
4) Wide open throttle RPM and speed with an average load (very helpful)
5) Engine/drive make, model, year, and HP
6) Boat make model, year, length and weight

 

[Genjem]

Re: Prop question

Ok. So I am wanting more hole shot. I thought about dropping to a 19p prop but I already turn 5000 Rpm at wot with 4 adults and full tank of gas. This yields 43 mph. My prop is just the mirage not the plus.

 

[Levinz11]

Re: Prop question

Try the Solas 4 blade. You won't break the bank. I went from a SS 3 blade 21" to a 4 blade 19" Solas and love it. Granted, my 21" was pretty beat.

 

[Genjem]

Re: Prop question

My 21 has seen a lot of use also. Lots of nicks around the edge of the blades. Did you lose much top end? Is the 4 blade stainless?

 

[Tail_Gunner]

Re: Prop question

Ok. So I am wanting more hole shot. I thought about dropping to a 19p prop but I already turn 5000 Rpm at wot with 4 adults and full tank of gas. This yields 43 mph. My prop is just the mirage not the plus.

I know my post is a speed bump but what little info you have posted is illuminating. Assuming your turning a 21p prop and your running 5000 means that engine is very healthly and your under propped. With that in mind your boat will react far better to trim tabs than any prop your going to buy Google nauticus trim tabs or do a search here you will find nothing but high marks.

As to the tech aspect here's a WAG......21p@ 5000 with 1.8 gearing...43mph gets 22% slip

Now take that to a unloaded boat with 10% slip and you get 50 mph which does make sense......but turning a fully loaded boat to 5000 rpm with a 21 or even a 20 makes one wonder.

 

[Genjem]

Re: Prop question

So are you saying my numbers aren't accurate? Little confused by the last post.

 

[Levinz11]

Re: Prop question

My 21 has seen a lot of use also. Lots of nicks around the edge of the blades. Did you lose much top end? Is the 4 blade stainless?

Not really because the 3 blade had some dings and was quite rough on the edges. Maybe 1-2

 

[Tail_Gunner]

Re: Prop question

So are you saying my numbers aren't accurate? Little confused by the last post.

Yes there is something not right...a boat load of people and turning a 21 to 5000 is bit strong. There is gearing number on your leg if you could post that it would help a lot.

 

[jestor68]

Re: Prop question

As usual, Tail Gunner has the scent

Looks like somebody's tachometer is off?

 

[jestor68]

Re: Prop question

deleted

 

[Genjem]

Re: Prop question

It is a 1.84 gear ratio. I have hoped all along it is my tact that is off. How do I tell?

 

[jestor68]

Re: Prop question

You can take it to a dealer and have them hook up their shop tach to compare readings.

They'll be able to run the motor at various rpm's to check the accuracy of your tach.

They might charge a nominal fee; or if you agree to buy the new tach(if necessary) from them, they most likely won't charge anything.

You might also try cleaning the pins on the back of your tach where the wires hook up. I have to do this about once a year lately to keep my 1996 tach working right.

 

[jestor68]

Re: Prop question

deleted

 

[dazk14]

Re: Prop question

I currently have a mirage 3 blade ss 21 pitch blade on my boat. Boat is 1993 18ft celebrity with 4.3lx. Wanting to go 4 blade to get more hole shot. Do I need ss or is aluminum ok?

Aluminum is fine. Plenty of very good 3 and 4 blade choices for $112 or less.

Tailgunner is correct. I can tell you with certainty that you can't turn a 21 mirage1 to 5000rpm. That's a 50mph setup and a mirage is big prop for a V6 to turn.

Your tach may simply be set to the wrong pole setting...What is the history of the boat.

There are lots of digital timing lights with tachs...even adjustable advances for relatively short money. You can probably borrow a tach from your local auto parts store.

Do you have a 4barrel carb?

An 18' boat will be greatly hampered by a large diameter prop(15.5") as someone has suggested.

You'll be in the 14"-15" diameter range. While you are working on getting your correct current WOT rpm's, you may as well indicate how the boat is used to better determine whether a 3 or 4 blade would be the best choice.

 

[Genjem]

Re: Prop question

I do have a 4 barrel carb. The boat is used on a small lake for pulling tubes and skiers. Although I am a speed freak I have already learned that this boat is not going to run 50 and still do what I want on the lower end. So are all mirage props large diameter? I can't tell how to read the diameter on this prop. Thanks all for the great replies and advice.

 

[Genjem]

Re: Prop question

So after searching my prop is a plus model and is 14 3/4" diameter. Is that still too big?