Advice on Possible Prop Swap

[barthel]

Morning All,

First, the particulars;

1) Performance issue you are trying to correct.
Boat is slow climbing out of the hole and seems to lose plane easily (below 2200rpm's)

2) Current prop manufacturer, model, aluminum or stainless as a minimum.
Volvo Penta QL Aluminum 3 blade

3) Current prop diameter and pitch (required).
14.25X21

4) Wide open throttle RPM and speed with an average load (very helpful)
4000-4200 with an "average" load

5) Engine/drive make, model, year, and HP
VP 4.3GLPEFS, VP SX Outdrive, 2000 model year/190HP

6) Boat make model, year, length and weight
Four Winns Horizon 180LE, 2001, 18ft, 2500#

Now, once the boat is up on plane it seems to run beautifully. Top speed at WOT (4100-4200rpm's) has been GPS'd at 47mph. My problem seems to be holeshot and slow speed planing. We don't do wakeboarding or skiing but do run towables and kneeboards. Recently I have added a set of Smart Tabs, it helped with trim/porpoising but had little effect with holeshot or low speed planing. Also, it looks like the boat had been down propped at least once. Four Winns shows this boat/engine combo came stock with a 14.25"X23 pitch prop, it currently has a 21p prop on it.

So, my question is would I be better served by down propping again (to a 19p), running a 4 blade aluminum or a 3 blade SS? I have no handling issues, the boat performs excellent, I would just like to get it on plane a bit faster and hold plane at a bit slower of a speed.

Thanks in advance for any opinions/advice.

 

[Leardriver]

Re: Advice on Possible Prop Swap

You want your RPM's to be around 4800 lightly loaded.

You are in between a 17 and a 19 pitch prop, which makes me lean towars a 17 pitch 4 blade aluminum. Those are $90 everywhere. You probably don't spend much time running wide open, so watch your top RPM's, and you will love the hole shot.

 

[jestor68]

Re: Advice on Possible Prop Swap

WOT rpm range for your motor is 4400-4800 rpm.

You need 600 more rpm to reach optimum rpm.

The quicksilver 15-1/2 X 18 pitch aluminum prop is what I would put on it, if it were my boat. It will turn 4700 rpm at WOT, and accelerate like nothing you have experienced yet.

Depending upon how much you want to spend; Solas makes a SS 4 blade 15 X 18 that would work even better for water sports. But I feel; for the money, the Quicksilver is the better bang for the buck.

 

[barthel]

Re: Advice on Possible Prop Swap

You are correct, I don't spend much time in the upper registers of the RPM range. 90% of the time I'm cruising between 2400 and 3200 RPM's

Jestor, if I put a 15 1/2 X 18 aluminum, would that be a 3 or 4 blade? The book on my engine show the WOT range from 4200 to 4600 RPM's. I'm at the lower end of that now but struggle to understand why if the boat has been down propped once already. If I'm understanding everything correctly, it should have pushed the RPM's up a bit.

 

[jimmbo]

Re: Advice on Possible Prop Swap

I've had very good results with the Mercury Enertia. In your case a 19" would just about right.

 

[steelespike]

Re: Advice on Possible Prop Swap

We seem to be ignoring the reason for down sizing the prop.
If the factory recommends a 23" prop it should be able o run within its rpm range with it.
Certainly not good for water sport but should produce speeds at 50 or above.
Hole shot a little slow.
At 21" I would think normally hole shot would be acceptable and you might have to watch rpm depending on the load.
Anything lower than 21 your approaching special,load and/or activities might require.
Are you sure it trims down all the way for hole shot? Is the motor in excellent tune and timing set right and advancing as it should?
is the bottom clean and smooth?Is the throttle opening all the way?
Perhaps the boat has absorbed water over the years.
Wouldn't hurt to do a compression check.

 

[barthel]

Re: Advice on Possible Prop Swap

Boat is in tune (as far as 'excellent' I'm not sure but I did it myself), trim is full down during hole shot. Bottom is clean and smooth. I do have to check the timing (ordered the plug), and will do a compression check this weekend.

Te top speed listed by the manufacturer was 52mph with a 23p prop. I'm at 47 with a 21p, I guess I figured that was close. As to why it was down propped, not real sure. I bought the boat from a broker and never talked to the PO.

 

[barthel]

Re: Advice on Possible Prop Swap

Ok, did some more thinking on this, would someone mind confirming my thoughts?

When we do any watersports, we'll have at least 4 people, a half a tank of gas and a 48 qt cooler. Not exactly full loaded but not "lite" either. Under those circumstances I can see why the holeshot would be a bit slow.

I'm beginning to think that my tach is off as I am close to full factory speed with a downed prop (21p vs. 23p factory, 47mph vs. 52mph factory) yet I'm only indicating about 4100-4200 rpm's.

Based on what I know so far, I'm thinking that a 14 1/4 X 19p 4 blade aluminum would help my situation. Not destroy my top end (even though I spend almost no time there) but would give me a better shot out of the hole (quicker on plane, maybe less bow rise) and possibly keep me on plane at a slightly slower speed.

Or, following the "drop one size in pitch" theory, should I go with a 20p 4 blade?

Yes, no, maybe so?

Thanks again for all the options/opinions.

 

[steelespike]

Re: Advice on Possible Prop Swap

Thats kind of what I was talking about but I was wondering about power. Checking the tach may help eliminate a weak motor.
And taches do have a fairly high failure percentage. Some times you can correct the problem by operating the switch on the back to clean the contacts.
I do still wonder about the slow hole shot. Maybe you can quantify the hole shot Is it seconds or minutes?
Is it impossible unless everyone moves forward.

 

[barthel]

Re: Advice on Possible Prop Swap

I do still wonder about the slow hole shot. Maybe you can quantify the hole shot Is it seconds or minutes?
Is it impossible unless everyone moves forward.

No, not impossible at all.

My last boat was a 3.0L Stingray. If you gave it the beans, it growled and got on plane in a couple of seconds. With this boat, you gas it, the bow climbs (even with it trimmed full down), and it seems like it takes 4 or 5 seconds for it to climb out, get on plane and establish it. Once it's out, it runs beautifully, but will lose plane about 2100-2200 rpm's.

I may be making a mountain out of a molehill, but it just seems to me that it should climb out easier than it does. I'll be doing a timing/compression check later in the week to rule out a weak motor, but it doesn't seem weak. It responds quite well, just not out of the hole.

 

[barthel]

Re: Advice on Possible Prop Swap

OK,

So, I read what everyone wrote and did a TON of other reading here and elsewhere. I think I've come to a decision, I just need someone to either confirm my thinking or talk me out of it.

My main train of thought is to go with the Solas Amita 4, 14.25 X 19p 4 blade aluminum. Given my current situation it seems to be the best all around idea I can come up with.

My only question is, should I go with a 20p as opposed to a 19p? I'm currently running a 21p, 14.3" 3 blade.

Thanks for all who have invested time and effort ot read this. :facepalm:

 

[bnicov]

Re: Advice on Possible Prop Swap

You aren't going to stay on plane at just over 2k rpms. It's impossible. As for the slow hole shot, remember, you have 4 adults on the boat with a big cooler. You are a bit low on the rpms at WOT so a 19 pitch should be about perfect for your typical load out. You'll bring up your revs a bit and help out the hole shot. As for steel or aluminum, depends on two things, 1)your budget, and 2)does your regular boating waters contain rocky shoals and sumbmerged timber??
Have fun, there is no exact science when it comes to picking out a prop, you can get pretty close but you still need to try different options out, just because a prop worked for one person doesn't mean it will work for you.

 

[steelespike]

Re: Advice on Possible Prop Swap

I think that the 19 is a good choice it should give you a wider selection than an even numbered prop.
It will get you up quicker, stay up at reduced throttle better and may respond better around the dock.
Your top end will probably be lower.You may have to watch the rpm with a light load.
As far as your slower hole shot keep in mind the V6 is heavier than the 4 and while it has a bunch more hp it does have a higher gear ratio. Your new boat may have a deeper V than the old one which also could slow hole shot.

 

[barthel]

Re: Advice on Possible Prop Swap

UPDATE:

OK, so last dumb question (maybe)

And I have to apologize, I'm usually not so indecisive, but I'm still learning this whole boating thing. :facepalm:

So, given my situation (heavy load, slow holeshot, pulling & cruising) would I be better served by an aluminum 4 blade, 14.25 X 19p or a stainless steel 3 blade, 14.25 X 21p?

I'm mostly in the Colorado River (Parker Strip) and local Socal Lakes

 

[Water-is-life]

Re: Advice on Possible Prop Swap

UPDATE:

OK, so last dumb question (maybe)

And I have to apologize, I'm usually not so indecisive, but I'm still learning this whole boating thing. :facepalm:

So, given my situation (heavy load, slow holeshot, pulling & cruising) would I be better served by an aluminum 4 blade, 14.25 X 19p or a stainless steel 3 blade, 14.25 X 21p?

I'm mostly in the Colorado River (Parker Strip) and local Socal Lakes

I'm currently learning all this stuff too, but from my hours of research over the past couple weeks, it seems to me that for the hole shot you are looking for, and having a somewhat heavy load, you would be better off going with a 4 blade prop with the lower pitch. From my understanding it will improve hole shot and keep you on plane at a lower speed. Sorry for the long sentence. I currently have a 19ft Bryant with the 5.0 mercruiser running a 14 x 19p Stainless prop. I just got a new prop in the mail today and can't wait to try it out. I'm looking for the same results you are. The new one is an aluminum 4 blade 14.5 x 18p. Most of the guys with my setup run the Rev 4 SS 17p but I couldn't afford it right now so I'm going to see how this one works out. Good luck with yours.

 

[barthel]

Re: Advice on Possible Prop Swap

BTT for final question.

If I go with the SS, do I stay with the 21p, or do I have to drop pitch to 19?

 

[Water-is-life]

Re: Advice on Possible Prop Swap

If you want better hole shot and better planing speed you should drop pitch. Just don't let your engine over rev.