Chaparral Mercruiser Prop Question

[mastermind2]

I'm trying to replace my prop and have a few questions based on options shown below.

1. Unsure what pitch than my factory prop was but it was 3 blade Aluminum.

2. I initially replaced with a Quicksilver alumnium 3-blade 14" 19 pitch and my top speed was around 50 mph WOT seemed to be within the operating range. But it was very hard to get on plane with 8 passengers and pulling tubes. So I went to try a 4 blade...

3. Tried a Quicksilver 4-blade aluminum 14" 17 pitch, and my WOT jumped to 5400 and my top speed was barely 40 mph. Hole shot was good, but it was over revving.

4. Tried Turning points 4-blade aluminum 14" 19 pitch and my WOT dropped to 4400 and top speed for 43 mph. Not even hitting the minimum range of the manufacturer WOT range.

5. Turning point is saying my boat must not handle 4-blade well and to exchange it for 3-blade 19".

So at this point I'm stuck. I don't want my WOT to be too high and risk damaging engine. and having a WOT lower than manufactures specs seems to mean I'm losing performance.

I do mostly tubing with average of 6 people on board. Was looking for better acceleration and hole shot and easier plane, but wasn't expecting 10mph reduction in top speed.

Thoughts anyone

 

[mastermind2]

Forgot to mention. Manufacturer operating range is 4800-5200. MerCruiser sterndrive. 4.5L 250hb 1.62:1

 

[briangcc]

Most props are stamped with the size/pitch and/or model number. May be in the exhaust, may be on the hub between blades.

You're going to need to consistently test with 6 people on board. Adding to your passenger count can (and will depending on the situation) require a prop change and liberal use of the right hand to feather the throttle when not so many are on board.

 

[jlh3rd]

what year/model boat.
are you overloading the boat? Then expecting great performance? 8 passengers +pulling tubes?.
As an example, I propped my pontoon to get a little over the max rpm when by myself so that when loaded with two tubes pulling 5 teens, and 4 adults, I could pull fast enough to not bore the kids, using a 3 blade-16x12. But that lowered my top end when by myself to about 23 mph.
Using a 4blade 14x14 gives me about 26mph@5800 when alone, but trying to pull teens and adults put me at 5200-5300 rpm and 17 mph, too low...for me.
Point being, its a compromise in most cases. Your trading one performance # for another. You can tweak the #'s trying different props, but that can get expensive.
It's not necessarily the # of blades. Pitch, diameter, blades, cupping, blade design all play a roll.
Like someone stated, if you want to pull tubes AND have 8 people on board AND have a range of performance to suit you, you need to prop for max rpm or slightly over for that weight. But top end will suffer.
To solve that, you need more power.

My 4-14x14 prop and the 3-16x13 prop are practically equal in performance.

 

[mastermind2]

what year/model boat.
are you overloading the boat? Then expecting great performance? 8 passengers +pulling tubes?.
As an example, I propped my pontoon to get a little over the max rpm when by myself so that when loaded with two tubes pulling 5 teens, and 4 adults, I could pull fast enough to not bore the kids, using a 3 blade-16x12. But that lowered my top end when by myself to about 23 mph.
Using a 4blade 14x14 gives me about 26mph@5800 when alone, but trying to pull teens and adults put me at 5200-5300 rpm and 17 mph, too low...for me.
Point being, its a compromise in most cases. Your trading one performance # for another. You can tweak the #'s trying different props, but that can get expensive.
It's not necessarily the # of blades. Pitch, diameter, blades, cupping, blade design all play a roll.
Like someone stated, if you want to pull tubes AND have 8 people on board AND have a range of performance to suit you, you need to prop for max rpm or slightly over for that weight. But top end will suffer.
To solve that, you need more power.

My 4-14x14 prop and the 3-16x13 prop are practically equal in performance.

2021 chaparral ssi.

With a 3 blade 19” I could still pull tubes with 8 people just fine once on plane. It did take several seconds longer on hole shot to get on plane with the weight but even with 8 ppl on board I could run 50th (not tubing at that speed)

I was trying to improve hole shot, acceleration to get on plane faster and bow lift. Which I read a 4 blade would do that with only slight top end impact 3-4 mph. But when I went to 4 blade I dropped by 10 - 15 rpm mph on a 17” at max rpm and I can’t even get to high enough rpm on a 19” (even by myself)

So I started thinking about the brand of prop. Are aluminum quicksilver and turning point props good. Or is their a better performing one.

 

[Scott06]

2021 chaparral ssi.

With a 3 blade 19” I could still pull tubes with 8 people just fine once on plane. It did take several seconds longer on hole shot to get on plane with the weight but even with 8 ppl on board I could run 50th (not tubing at that speed)

I was trying to improve hole shot, acceleration to get on plane faster and bow lift. Which I read a 4 blade would do that with only slight top end impact 3-4 mph. But when I went to 4 blade I dropped by 10 - 15 rpm mph on a 17” at max rpm and I can’t even get to high enough rpm on a 19” (even by myself)

So I started thinking about the brand of prop. Are aluminum quicksilver and turning point props good. Or is their a better performing one.

I think if you want to do watersports with 8 people ( big ask of any boat) you will need to try a couple props, best to find a shop either local or on line that you can talk with and try a few.

I have never used TP props but have read mixed reviews here.

I had really good luck with Michigan Vortex 4 blade props. Based on your comments 19" 3 blade hits proper WOT rpm- would try a 18" Likely you will have similar rpm as the 19".

Quicksilver /merc props are very good. The Al ones are more of an entry level prop vs a SS one. I have also had good luck with the Vensura/Offshore prop and what I currently run a Revolution 4. they are way more money, which is why it is best to try before you buy. I think Places like Prop MD and Prop Gods do this maybe Bblades as well. would call them and see what you can work out in terms of exchange

 

[mastermind2]

I think if you want to do watersports with 8 people ( big ask of any boat) you will need to try a couple props, best to find a shop either local or on line that you can talk with and try a few.

I have never used TP props but have read mixed reviews here.

I had really good luck with Michigan Vortex 4 blade props. Based on your comments 19" 3 blade hits proper WOT rpm- would try a 18" Likely you will have similar rpm as the 19".

Quicksilver /merc props are very good. The Al ones are more of an entry level prop vs a SS one. I have also had good luck with the Vensura/Offshore prop and what I currently run a Revolution 4. they are way more money, which is why it is best to try before you buy. I think Places like Prop MD and Prop Gods do this maybe Bblades as well. would call them and see what you can work out in terms of exchange

Thanks for info. Also 8 ppl max is typical all I ever had and when tubing 2 of those are on tube. So just wanted to be clear it would be 6 on boat and 2 on tube. Not 8 on boat and 1 or 2 doing sports.

Will look into the resources you mentioned.

Thanks

 

[Scott06]

Thanks for info. Also 8 ppl max is typical all I ever had and when tubing 2 of those are on tube. So just wanted to be clear it would be 6 on boat and 2 on tube. Not 8 on boat and 1 or 2 doing sports.

Will look into the resources you mentioned.

Thanks

I wasn't counting that close.... Your use is similar to mine

I have a 2004 Sea Ray 200 sport (20.5') with a 5.0 Carbed engine (about 240-260 hp as It is a 4 bbl Edlebrock carb). It was a 4.3 boat that I repowered so it has the steeper V6 drive ratio (1.81:1). I run a 21" Revolution 4 prop.

With your set up would probably se e similar rpm with a 19" If you went with something like a rev 4 I would try an 18" or 17" pitch as they have huge blades with a fair amount of cup. If you can try before you buy its best as hard to guess pitch from the keyboard

 

[jlh3rd]

"3. Tried a Quicksilver 4-blade aluminum 14" 17 pitch, and my WOT jumped to 5400 and my top speed was barely 40 mph. Hole shot was good, but it was over revving."

I reread all your posts:

Was this when you were loaded up?...If not, then that prop just might work for you when you are loaded. That's what I had to do for my pontoon situation. I traded speed for "torque". So we need to know exactly what your load was when reporting your speed and rpm's for each prop.

so, what that says to me, is that you need a 4-14x18....or equivalent (reread my post)
on paper, that should bring you down in rpm, hopefully to the max of 5200. For that particular load you were under.

I'll repeat..propping on paper doesn't mean the actual results will reflect that. And opinions not based on experience are not helpful much. for example -
"your boat doesn't handle 4 blades well"....really?..what does that mean..
and speed is just secondary, or will be what it will be.
You're looking for a proper rpm while under load coupled with a better hole shot hopefully, right? Not speed, right?....you can't have everything.

 

[Cortes100]

3. Tried a Quicksilver 4-blade aluminum 14" 17 pitch, and my WOT jumped to 5400 and my top speed was barely 40 mph. Hole shot was good, but it was over revving.

4. Tried Turning points 4-blade aluminum 14" 19 pitch and my WOT dropped to 4400 and top speed for 43 mph..

One problem is comparing different brands of props makes it even harder to find the right one. Pitch is only 1 factor.
I would try the Quicksilver (Nemesis) 4 blade 19 pitch. The 17 you tried was pretty close so go up one size. Going to the Turning point 19 is a totally diff prop so it's tough to compare to the QS.
FWIW, my previous boat had the 4.5L Alpha. I always used the 4Blade Merc props. 19 with a full load or 21 with light load. Both would just tag the limiter under perfect trimmed out conditions.. Both 3 blade (Blackmax) and 4 blade (Nemesis/spitfire) props provided the same WOT rpm but the 4 blade outperformed in every way.

 

[tpenfield]

Which Chappy SSI model? The 21 (3100 lbs) or the 23 (3600 lbs)

The original prop (14 x 19 Al) seems to be optimized for the top range . . . maximum speed. It is surprising that the 17 pitch 4-blade had such a dramatic effect. . . . but you did not state what the RPM was with the 19 pitch 3-blade. if it was at/near the 5200 RPM limit, you could try a 19 pitch
4-blade . . . or maybe a 17 pitch stainless steel 4-blade.

I assume the 50 mph WOT of the 19 pitch prop was with a typical load (6-8 peeps)?

The challenge is that you are trying to optimize both ends of the performance spectrum (top speed vs. time-to-plane with heavier load). No prop is going to do both. So, you will what to find a prop that does not over rev the engine (BTW - your engine should keep itself from going too far over the recommended maximum RPM)

Boats usually come from the manufacturer with the best overall prop, and I think that is what you are finding. I would think you could try a stainless steel 4 blade 17 pitch to see where that gets you.

 

[bruceb58]

Talk to Bryan at Valley Propellerthe guy knows his stuff.

I use Solas propellers on my Bravo 3. Bryan has the best prices.

Valley Propeller Service

www.valleypropellerservice.com

 

[QBhoy]

Hi. From what you’ve said. Just a few things to add.
You’re going well to see 50mph with that load and engine/boat set up. I’d encourage you to not stray too far from what you have. If that’s with an ally 19” 3 blade. It screams to me that you might just be almost as good as it gets, if you put a good 3 blade stainless 19” 3 blade on her. A nice tempest plus 19” might just have you perfect. Keep your rpms just in the sweet spot, improve efficiency, acceleration, cruising and top end too.
Ps…don’t worry too much about your top end rpm there. You’ll hit the limiter usually about 100-150 rpm over the rpm max range figure. A tempest 19” will bring your rpms in check a little I’d say. They can act almost like an inch more pitch than they are for that…compared to most other 19”. Big bladed diameter on them.
Also. Can’t urge you enough to get yourself a vessel view mobile device. Couple hundred quid and is just amazing for giving you exact rpm from the ecu. Ideal for propping a boat. But also for so many more things too. Working out your best cruise speed and showing countless additional pressures and temps that the gauges on the dash just don’t or can’t. Fuel range and usage too. Not to mention saving a trip to the dealer for any fault diagnostics. Tells you all faults too.