OUTRAGE 24: Propeller: Vengeance or SWS Yamaha

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Author Topic:   OUTRAGE 24: Propeller: Vengeance or SWS Yamaha

aquaman posted 05-23-2005 12:31 AM ET (US)
I've been running a 17-inch pitch Yamaha SWS on my 1994 24 Outrage with a 250-HP EFI Yamaha for the last year with performance numbers as follows:
4,000rpm = 30.3mph
5,600rpm WOT = 43.5mph
This weekend I tried a 19-inch pitch SWS with the result:
4,000rpm = 34.5
5,100rpm WOT = 46.0mph
Measured with Lowrance X-15 GPS
The 19 appears to be a better match at cruise giving me just over 3-MPG. Is 5,100 at WOT within maximum range? Any ideas how the Vengeance might compare to the SWS Yamaha? My Yamaha dealer concurs Merc makes a better prop.
John
jimh posted 05-23-2005 08:45 AM ET (US)
You'd have to tell us what the recommended maximum RPM is for your motor. You can probably find that information in the owner's manual.
What is your lower unit gear ratio?
Sal DiMercurio posted 05-23-2005 12:26 AM ET (US)
John, I really do doubt your getting 3 mpg at 4000 rpms on that rig.
Do you have a flow scan,....if so, it's off.
What is the factory maximum RPM recomendation for that engine?
Just because your getting more speed certainly dosen't mean your getting better fuel economy.
Let me explain why your get "LESS" mpg with the 19p prop at 4000 rpms than you were with the 17p prop.
With the 17p you were getting 30 mph at 4000 rpms with the throttle at x amount of inches from the idle position, now with the 19p prop your having to put the throttle farther forward [ to the 4500 rpm mark with a 17 p ] in order to reach 4000 rpms because your now 500 rpms "BEHIND" .
You don't just loose 500 rpms at the top end, you loose it the second you put the engine in gear.
No doubt about it, Merc makes the best props with the most selections of anyone.
They also have the universal hub but a merc hub will fit your Yamaha.
When testing for maximum rpms are you trimming the engine out as far as you can without her blowing out, or are you just leaving her tucked all the way in ?
To correctly test for max rpms you must go to wot, than max trim.
I don't know where you got the idea your getting better mpg with the 19p.
Your engine is working 500 rpms harder with the 19p compared to the 17p.
When an engine works harder, it get "LESS" milage per gallon.
Sal
jimh posted 05-23-2005 01:15 PM ET (US)
[Moved from multiple other threads.]
LHG posted 05-23-2005 06:57 PM ET (US)
I would try the Mirage Plus line of props first, probably a 17" pitch, based on what the Yamaha is giving you in RPM. I have noticed that BW usually installs Mirage props on larger Whalers powered with a single, based on their own testing, I presume. Mirage Plus props are widely used on the 225/250HP Yamaha Ox66's, and the large blade surface and diameter is what carries the load so well.
aquaman posted 05-23-2005 07:21 PM ET (US)
Sal,
The only fuel flow calc I use is fill the tank, run a distance at 4,000, record the speed and refill the tank. Calculate the MPG. If you cover some distance, say 50 to 90 miles, I think it can be fairly accurate. Maybe not that sophisticated but I sometimes question the accuracy of fuel flow guages. Thanks for clarifying additional possible fuel burn at a given RPM. I figure fuel burn at WOT would be the same no matter which prop you were running because a fuel system only has the ability to put out so much fuel but I see your point moving through the throttle range... I haven't had the 19" on a long trip yet to calc MPG fill-up to fill-up.
LHG,
You recommend a 17" Mirage, do you think my set-up possibly can't turn the 19" Mirage at WOT with the 5,000-5,500 RPM mark? Is there more blade area on the Mirage as compared to the SWS? I have never been able to find any performance tests done by Whaler, are they available?
Thanks for the input.
John
Tom W Clark posted 05-23-2005 08:59 PM ET (US)
John,
Your motor has a full throttle operating range of 4500 to 5500. The gear ratio is 1.81 I believe.
If the Yamaha 17" prop was hitting 5600 then I'm with Larry, try a 17" Mirage. The Mirage has more blade area. On the other hand if you want to try a 14.25 x 19 Stiletto Advantage II, I have a pair and you could borrow one.
LHG posted 05-23-2005 09:07 PM ET (US)
Mercury Mirage Plus props run quite efficiently in slippage, so they often will hold down RPM relatively to other props of the same pitch. This is the same as saying they have more effective pitch, an inch or two. I do not know how they compare in "effective pitch" to the Yamaha props, but I would guess 17" in a Mirage is all she'll be able to turn, and you may only get 5300 RPM or so. Go to whaler.com for performance test results, which also indicate prop being used. Check out the 240 Outrage with single 225 Optimax as a close example to your boat.
Also check out Mercury prop descriptions and applications on mercuymarine.com. Lots of good information there.
I don't know how the Yamaha 250 is geared, but with a Merc 250 EFI geared at 1.76, a 17" Mirage is shown in the prop charts as a solid 50 MPH prop. At 1.86 gearing of the 2.5 liter V-6's, it's shown as a 46 mph prop.
From my experience with a Mirage, they have an exceptionally strong (higher speed relative to engine RPM) mid-range, as in cruising/general boating. Mercury recommends medium size vent plugs for outbard applications, and closed vents for stern drive applications. They come with closed vents, since the prop has large V-8 stern drive application.
aquaman posted 05-24-2005 01:35 PM ET (US)
Thanks for the info. I think I'll try a Mirage Plus 17" and see how it works...
John

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Author	Topic: OUTRAGE 24: Propeller: Vengeance or SWS Yamaha
aquaman	posted 05-23-2005 12:31 AM ET (US) I've been running a 17-inch pitch Yamaha SWS on my 1994 24 Outrage with a 250-HP EFI Yamaha for the last year with performance numbers as follows: 4,000rpm = 30.3mph 5,600rpm WOT = 43.5mph This weekend I tried a 19-inch pitch SWS with the result: 4,000rpm = 34.5 5,100rpm WOT = 46.0mph Measured with Lowrance X-15 GPS The 19 appears to be a better match at cruise giving me just over 3-MPG. Is 5,100 at WOT within maximum range? Any ideas how the Vengeance might compare to the SWS Yamaha? My Yamaha dealer concurs Merc makes a better prop. John
jimh	posted 05-23-2005 08:45 AM ET (US) You'd have to tell us what the recommended maximum RPM is for your motor. You can probably find that information in the owner's manual. What is your lower unit gear ratio?
Sal DiMercurio	posted 05-23-2005 12:26 AM ET (US) John, I really do doubt your getting 3 mpg at 4000 rpms on that rig. Do you have a flow scan,....if so, it's off. What is the factory maximum RPM recomendation for that engine? Just because your getting more speed certainly dosen't mean your getting better fuel economy. Let me explain why your get "LESS" mpg with the 19p prop at 4000 rpms than you were with the 17p prop. With the 17p you were getting 30 mph at 4000 rpms with the throttle at x amount of inches from the idle position, now with the 19p prop your having to put the throttle farther forward [ to the 4500 rpm mark with a 17 p ] in order to reach 4000 rpms because your now 500 rpms "BEHIND" . You don't just loose 500 rpms at the top end, you loose it the second you put the engine in gear. No doubt about it, Merc makes the best props with the most selections of anyone. They also have the universal hub but a merc hub will fit your Yamaha. When testing for maximum rpms are you trimming the engine out as far as you can without her blowing out, or are you just leaving her tucked all the way in ? To correctly test for max rpms you must go to wot, than max trim. I don't know where you got the idea your getting better mpg with the 19p. Your engine is working 500 rpms harder with the 19p compared to the 17p. When an engine works harder, it get "LESS" milage per gallon. Sal
jimh	posted 05-23-2005 01:15 PM ET (US) [Moved from multiple other threads.]
LHG	posted 05-23-2005 06:57 PM ET (US) I would try the Mirage Plus line of props first, probably a 17" pitch, based on what the Yamaha is giving you in RPM. I have noticed that BW usually installs Mirage props on larger Whalers powered with a single, based on their own testing, I presume. Mirage Plus props are widely used on the 225/250HP Yamaha Ox66's, and the large blade surface and diameter is what carries the load so well.
aquaman	posted 05-23-2005 07:21 PM ET (US) Sal, The only fuel flow calc I use is fill the tank, run a distance at 4,000, record the speed and refill the tank. Calculate the MPG. If you cover some distance, say 50 to 90 miles, I think it can be fairly accurate. Maybe not that sophisticated but I sometimes question the accuracy of fuel flow guages. Thanks for clarifying additional possible fuel burn at a given RPM. I figure fuel burn at WOT would be the same no matter which prop you were running because a fuel system only has the ability to put out so much fuel but I see your point moving through the throttle range... I haven't had the 19" on a long trip yet to calc MPG fill-up to fill-up. LHG, You recommend a 17" Mirage, do you think my set-up possibly can't turn the 19" Mirage at WOT with the 5,000-5,500 RPM mark? Is there more blade area on the Mirage as compared to the SWS? I have never been able to find any performance tests done by Whaler, are they available? Thanks for the input. John
Tom W Clark	posted 05-23-2005 08:59 PM ET (US) John, Your motor has a full throttle operating range of 4500 to 5500. The gear ratio is 1.81 I believe. If the Yamaha 17" prop was hitting 5600 then I'm with Larry, try a 17" Mirage. The Mirage has more blade area. On the other hand if you want to try a 14.25 x 19 Stiletto Advantage II, I have a pair and you could borrow one.
LHG	posted 05-23-2005 09:07 PM ET (US) Mercury Mirage Plus props run quite efficiently in slippage, so they often will hold down RPM relatively to other props of the same pitch. This is the same as saying they have more effective pitch, an inch or two. I do not know how they compare in "effective pitch" to the Yamaha props, but I would guess 17" in a Mirage is all she'll be able to turn, and you may only get 5300 RPM or so. Go to whaler.com for performance test results, which also indicate prop being used. Check out the 240 Outrage with single 225 Optimax as a close example to your boat. Also check out Mercury prop descriptions and applications on mercuymarine.com. Lots of good information there. I don't know how the Yamaha 250 is geared, but with a Merc 250 EFI geared at 1.76, a 17" Mirage is shown in the prop charts as a solid 50 MPH prop. At 1.86 gearing of the 2.5 liter V-6's, it's shown as a 46 mph prop. From my experience with a Mirage, they have an exceptionally strong (higher speed relative to engine RPM) mid-range, as in cruising/general boating. Mercury recommends medium size vent plugs for outbard applications, and closed vents for stern drive applications. They come with closed vents, since the prop has large V-8 stern drive application.
aquaman	posted 05-24-2005 01:35 PM ET (US) Thanks for the info. I think I'll try a Mirage Plus 17" and see how it works... John