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Author Topic:   New Outboard Comparative Noise Levels

tmann45 posted 11-11-2008 08:07 PM ET (US)
I would like to get some real world noise level comparisions on new 200-250 horsepower outboard engines. Yes, I am looking to replace my 10-year old Mercury 200HP Offshore carburated engine with something new. (Yes it is for sale, just rebuilt.) If anyone has experience with the different engines compared to other brands in the horsepower range specified, please give me your opinion. If I get enough responses, I can rank them in a relative order.
Yes, there are dB stats out there, but I think the human ear is a better measuring device.
Tom
jimh posted 11-11-2008 08:32 PM ET (US)
Tom--The human ear is not much of a measuring device. Hearing memory lasts about ten seconds. If two sounds are compared with more than ten seconds of separation, the human ear has difficulty making any accurate comparison.
fourdfish posted 11-11-2008 10:28 PM ET (US)
The truth is some people will say one engine is quieter than another simply because they own it.
A lot of factors will change the perception of how an engine sounds so it would be much better off to use an instrument to measure the sound.
Several different qualities of sound exist besides amplitude. Some loud sounds will please the ear and will give the impression of lower amplitude.
jimh posted 11-11-2008 11:04 PM ET (US)
Tom--Even though I earlier disqualified what I am about to say, my ear tells me there are about four levels of outboard motor sound signature:
The Unbelievably Quiet At Idle
The six-cylinder Verado motor is just about alone in this category.
The Really Quiet At Idle
Most modern four-cycle motors are in this category.
Quiet At Idle
The E-TEC two-cycle, maybe a few others are in this category.
Not Too Loud At Idle
Most of the rest of the modern outboards are in this category.
Once you get off idle speed, noise increases, and in some cases quite rapidly. By the time you get to wide-open throttle, the differences become smaller. However, most people are impressed more by the idle speed sound signature than anything else. This quality seems to make a big impact.
Many sound level measurements are published, but there is scant detail about how they those measurements were taken. This makes comparison difficult. Unless very consistent measurement technique were used, and unless the measuring equipment was consistently calibrated to a known reference standard, there is not much validity in comparing the results among different tests. This is particularly true when you consider the influence of the boat on the sound signature.
There is an ICOMIA standard for outboard motor sound, but unfortunately this data is not always provided for every motor. The E-TEC 250 H.O. motor, for example, rates at 84.0-dBa on the ICOMIA standard. But I don't have any other outboard motor ratings to compare to this.
So we're back to the by-ear technique. As Fourd' mentions, these observations are subject to some outside influences, especially how much someone likes their new motor.
I don't think you'll get too much argument on the six-cylinder Verado--it is the quietest motor I've heard.
hauptjm posted 11-12-2008 10:17 AM ET (US)
I agree with the assessment of the Verado. It is by far, the quietest motor I have ever witnessed. I think the assumption of most folks being impressed by the idle sound dampening versus the relative noise levels at speed are also accurate.
When I think to my own experiences, your "idle" time is when you expect to have conversation, dock the boat, relax maybe from a hard ride at speed, or some other more exhilarating part of the boat ride. That said, the quiet of an engine is more appreciated. I expect the noise level to go up considerably at speed, so I'm not disappointed when the Verado or any other modern outboard "sings" when revving.

highspeed_jd posted 11-12-2008 05:13 PM ET (US)
I like a louder motor. They seem to raise more fish.
tmann45 posted 11-12-2008 07:47 PM ET (US)
Looks like I left out an important part of my request, I am more concerned about perceived noise level at cruising speed, say 3500 to 4500 rpm range.
Where I boat I can avoid no wake / idle speed zones and usually do even though that adds a couple of miles to the trip.
And yes, I agree that for measuring dB, the ear is least reliable, just like your eyes, they can adjust to a wide range of levels. The style of boat and transom could make a huge difference in perceived noise level also.

quote:
the six-cylinder Verado--it is the quietest motor I've heard.

Ok Jim, how much quieter are the Verado's compared to the E-TEC at cruising speed?
jimh posted 11-12-2008 08:16 PM ET (US)
I can't really offer any meaningful comparison between the noise level of a Verado and that of an E-TEC at cruising speed, and that is because, even though I have a accumulated many hours of experience with each motor, there is a substantial amount of time between when I heard the Verado and when I heard the E-TEC. So there is no telling by ear if there is a reasonably perceivable difference. I can't remember sound level and pitch that accurately.
I have found that there is some technical documentation on the sound level measurement of boats and motors.
ICOMIA Standard 39-94
Small craft-Measurement of duty cycle operator sound pressure level
http://www.icomia.com/library/library.asp?Page=2&view=Category&LC_ID=14& FT_ID=&CT_ID=&sort=#
This is the standard I mentioned previously by which the E-TEC 250 H.O. motor was measured and rated at 84.0-dBa. To get a reasonable answer to your question, which is quieter, the Verado or the E-TEC, all we need is for Mercury to publish a similar measurement of their 250-HP Verado motor according to the guidelines provided by this standard. If Mercury would do that, we could make a simple comparison and have an answer that was based on science instead of marketing.
mobey posted 11-13-2008 08:36 AM ET (US)
Try this- Go to youtube.com and type in various outboard and boat words or phrases like: "evinrude", "yamaha outboard", "verado", "mercury", "opti", "optimax", "e-tec" "e-tech", "outboard", "bass boat", "boston whaler", etc. etc. - listen to a bunch of the video/sound clips. Maybe include the horsepower numbers with the various outboard brands/models like "225 mercury" or "evinrude 250". I checked this out a lot. To me, many of the outboards (particularly the two stroke motors) were loud, harsh, irritating, or otherwise just not pleasant- especially when droning on for longer periods of time. Listening to the outboards on You Tube was a big part of my decision in purchasing my 300 Verado. I found the 6 cylinder Verado to have a pleasing- not annoying/tiring sound. At idle it is virtually silent.
fourdfish posted 11-13-2008 01:38 PM ET (US)
How about a side by side comparison! I did have that chance
and mine is quieter! Give me a break! Does it matter?
BTW-- idle at 450 rpms! Cannot hear it at the helm!
alfred posted 11-14-2008 06:40 AM ET (US)
I know that you are asking about the 6 cylinder and I haven't heard one run, so I can't say how quiet it is, but I can say that not all of the 4 stroke 4s are the same.
The 150 Verado is quiet, but when I have my boats side by side (Verado 150 and Johnsuki 140) and both motors running at idle, I can only hear the Verado, regardless of which boat I am in.
The Johnsuki is really quiet. True it's 10HP less, but I don't think the 10HP makes much difference at idle.
On the run, both seem about the same.
RJG posted 11-14-2008 10:12 AM ET (US)
I have been on all day, offshore fishing trips on boats powered by Suzuki, Yamaha and Evinrude.
The 32 Twinn Vee was powered by twin 250 Suzuki 4 strokes. While dead quiet at idle, they wore me out during the long run to and from the fishing grounds. Not a high pitched sound just a loud, low pitched drone. The boat itself could have been a contributing factor as well as there being two motors.
The 23 ft. Scout CC powered by a 225 Yamaha 4 stroke was again dead quiet at idle and also easy on the ears while at speed. A very quiet, low pitched drone that was easy to forget about during conversation but enough to listen to so as to keep in touch with the motor.
My own 250 E-TEC is on a 23 ft. Hydra-Sport WA. Very quiet at idle but not as quiet as a 4 stroke. A subtle rumble that is just enough to hear but not so as to interfere with conversation. At speed she compares with the Yamaha as far as sound level. Easy to forget about but enough to keep in touch with through wind noise.
The sound of an E-TEC at speed, to me, is one of authority. You just want to keep pushing the throttle further just to hear her go. And go she does. That big Hydra-Sport, with hardtop, will do 50+.
Peter posted 11-14-2008 10:27 AM ET (US)
The thing I notice between the 2-stroke and 4-strokes at speed is that the 2-strokes have a very well defined, everything in-sync sound signature. The 4-strokes at speed tend to produce a white noise type sound signature which I think is a result of valve train sounds and the combustion process sounds competing with each other making it difficult to "tune in". At speed I would not characterize the 4-stroke as being quieter but its frequency or frequency mix is clearly different.
swist posted 11-14-2008 11:36 AM ET (US)
Agree with Peter. 2-cycle engines, for the most part, have a more definite "pitch" (a chainsaw is the most obvious example). 4-cycle engines have much more a combination of frequencies.
I will posit, however, that this difference may be lessening as 2-cycle DI engines get more complicated and have more parts and processes that contribute to the noise spectrum.
And, yes, different people may react very differently to these various waveform spectra, in terms of perceived loudness, even if a decibel meter shows they are equal.
A2J15Sport posted 11-14-2008 09:28 PM ET (US)
We own two 75 HP Merc's on pontoons.
One is 2-stroke, the other 4 stroke.
As for noise, I can't tell. Their noise is different-period.
Have I attached decibel meters-no. Neither is objectionable, IMHO.
The biggest difference is: Starting and fuel economy. That's about it.
Lil Whaler Lover posted 11-15-2008 07:51 AM ET (US)
Try running both 2 strokes and 4 strokes on so-called rabbit ears and you will hear the difference.
Starting the 4 strokes, an older Mercury 115 EFI and a Yamaha F-60 provides a very quiet exhaust, not unlike starting a car with a similar sized engine.
When starting a 2 stroke, at least a 40 or larger and hear a sound that reminds me very much of a tuned pipe on a racing snowmobile. By the way, a tuned exhaust is necessary to optimize power/performance with a 2 stroke. The 2 stroke relies almost entirely on the water to silence it, where the 4 stroke is quiet anyhow.
We have heard several times of trailer boaters pulling their 4 stroke powered boats and not noticing that they forgot to shut the engine off. I have never heard of this happening with a 2 stroke, most likely due to the rather loud "snort" of a 2 stroke out of water.
Peter posted 11-15-2008 09:25 AM ET (US)
If you run DFI 2-stroke that uses stratified charging on ear muffs you will also hear a difference relative to that tuned pipe -- pop, pop, pop -- sound a carburated 2-stroke makes. The DFI 2-stroke is much quieter, much smoother. That typical uneven, loud, pop, pop, pop sound you typically hear out of a 2-stroke running on muffs is non-existent in a DFI 2-stroke. Part of the reason is that the DFI 2-stroke isn't consuming anywhere near the same amount of fuel that the carburated 2-stroke is at idle on the muffs and the combustion has happened with the exhaust port closed.
Also, the frequency of the exhaust sound between 2 and 4 stroke is different simply due to the number (frequency) of combustion events per flywheel revolution. The combustion frequency for 4-strokes that have the same number of cylinders as a 2-stroke is lower. For example, say we have two 115 HP 4-cylinder outboards both of which idle at 650 RPM. The idle exhaust pulse frequency for the 4-stroke is approximately 22 Hz and the exhaust pulse frequency for the 4-cylinder, 2-stroke is twice that, approximately 44 Hz. Even if the sound pressure levels for each were the same, because the human ear is "tuned" to hear the 44 Hz frequency more readily so than the 22 Hz frequency, the 2-stroke would seem louder even though objectively it is not. In other words, the sound pressure level at 22 Hz needs to be greater than at 44 Hz for there to be the same perceived loudness. See the equal loudness plot at www.phys.unsw.edu.au/jw/hearing.html for an understanding that the ear does not hear all frequencies equally.
seahorse posted 11-15-2008 09:51 AM ET (US)
there are dB stats out there, but I think the human ear is a better measuring device
All the 4 strokes and the Evinrude E-TEC are very quiet motors, especially compared to your present one. Verado is supposed to be the quietest at idle, but a low hum or something similar is all you hear from any of them.
At cruise speeds, a decible or so between them is hard to notice as the wind and waves make the most noise while you are on plane.
Just remember that with any of the above engines you can have a normal conversation at the stern at any speed, and that's what counts.
kglinz posted 11-15-2008 10:15 AM ET (US)
I use a very simple way of comparing sound levels. Can I hear my VHF at cruise RPM? Opti = NO. 4 Stroke = YES.

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Author	Topic: New Outboard Comparative Noise Levels
tmann45	posted 11-11-2008 08:07 PM ET (US) I would like to get some real world noise level comparisions on new 200-250 horsepower outboard engines. Yes, I am looking to replace my 10-year old Mercury 200HP Offshore carburated engine with something new. (Yes it is for sale, just rebuilt.) If anyone has experience with the different engines compared to other brands in the horsepower range specified, please give me your opinion. If I get enough responses, I can rank them in a relative order. Yes, there are dB stats out there, but I think the human ear is a better measuring device. Tom
jimh	posted 11-11-2008 08:32 PM ET (US) Tom--The human ear is not much of a measuring device. Hearing memory lasts about ten seconds. If two sounds are compared with more than ten seconds of separation, the human ear has difficulty making any accurate comparison.
fourdfish	posted 11-11-2008 10:28 PM ET (US) The truth is some people will say one engine is quieter than another simply because they own it. A lot of factors will change the perception of how an engine sounds so it would be much better off to use an instrument to measure the sound. Several different qualities of sound exist besides amplitude. Some loud sounds will please the ear and will give the impression of lower amplitude.
jimh	posted 11-11-2008 11:04 PM ET (US) Tom--Even though I earlier disqualified what I am about to say, my ear tells me there are about four levels of outboard motor sound signature: The Unbelievably Quiet At Idle The six-cylinder Verado motor is just about alone in this category. The Really Quiet At Idle Most modern four-cycle motors are in this category. Quiet At Idle The E-TEC two-cycle, maybe a few others are in this category. Not Too Loud At Idle Most of the rest of the modern outboards are in this category. Once you get off idle speed, noise increases, and in some cases quite rapidly. By the time you get to wide-open throttle, the differences become smaller. However, most people are impressed more by the idle speed sound signature than anything else. This quality seems to make a big impact. Many sound level measurements are published, but there is scant detail about how they those measurements were taken. This makes comparison difficult. Unless very consistent measurement technique were used, and unless the measuring equipment was consistently calibrated to a known reference standard, there is not much validity in comparing the results among different tests. This is particularly true when you consider the influence of the boat on the sound signature. There is an ICOMIA standard for outboard motor sound, but unfortunately this data is not always provided for every motor. The E-TEC 250 H.O. motor, for example, rates at 84.0-dBa on the ICOMIA standard. But I don't have any other outboard motor ratings to compare to this. So we're back to the by-ear technique. As Fourd' mentions, these observations are subject to some outside influences, especially how much someone likes their new motor. I don't think you'll get too much argument on the six-cylinder Verado--it is the quietest motor I've heard.
hauptjm	posted 11-12-2008 10:17 AM ET (US) I agree with the assessment of the Verado. It is by far, the quietest motor I have ever witnessed. I think the assumption of most folks being impressed by the idle sound dampening versus the relative noise levels at speed are also accurate. When I think to my own experiences, your "idle" time is when you expect to have conversation, dock the boat, relax maybe from a hard ride at speed, or some other more exhilarating part of the boat ride. That said, the quiet of an engine is more appreciated. I expect the noise level to go up considerably at speed, so I'm not disappointed when the Verado or any other modern outboard "sings" when revving.
highspeed_jd	posted 11-12-2008 05:13 PM ET (US) I like a louder motor. They seem to raise more fish.
tmann45	posted 11-12-2008 07:47 PM ET (US) Looks like I left out an important part of my request, I am more concerned about perceived noise level at cruising speed, say 3500 to 4500 rpm range. Where I boat I can avoid no wake / idle speed zones and usually do even though that adds a couple of miles to the trip. And yes, I agree that for measuring dB, the ear is least reliable, just like your eyes, they can adjust to a wide range of levels. The style of boat and transom could make a huge difference in perceived noise level also. quote: the six-cylinder Verado--it is the quietest motor I've heard. Ok Jim, how much quieter are the Verado's compared to the E-TEC at cruising speed?
jimh	posted 11-12-2008 08:16 PM ET (US) I can't really offer any meaningful comparison between the noise level of a Verado and that of an E-TEC at cruising speed, and that is because, even though I have a accumulated many hours of experience with each motor, there is a substantial amount of time between when I heard the Verado and when I heard the E-TEC. So there is no telling by ear if there is a reasonably perceivable difference. I can't remember sound level and pitch that accurately. I have found that there is some technical documentation on the sound level measurement of boats and motors. ICOMIA Standard 39-94 Small craft-Measurement of duty cycle operator sound pressure level http://www.icomia.com/library/library.asp?Page=2&view=Category&LC_ID=14& FT_ID=&CT_ID=&sort=# This is the standard I mentioned previously by which the E-TEC 250 H.O. motor was measured and rated at 84.0-dBa. To get a reasonable answer to your question, which is quieter, the Verado or the E-TEC, all we need is for Mercury to publish a similar measurement of their 250-HP Verado motor according to the guidelines provided by this standard. If Mercury would do that, we could make a simple comparison and have an answer that was based on science instead of marketing.
mobey	posted 11-13-2008 08:36 AM ET (US) Try this- Go to youtube.com and type in various outboard and boat words or phrases like: "evinrude", "yamaha outboard", "verado", "mercury", "opti", "optimax", "e-tec" "e-tech", "outboard", "bass boat", "boston whaler", etc. etc. - listen to a bunch of the video/sound clips. Maybe include the horsepower numbers with the various outboard brands/models like "225 mercury" or "evinrude 250". I checked this out a lot. To me, many of the outboards (particularly the two stroke motors) were loud, harsh, irritating, or otherwise just not pleasant- especially when droning on for longer periods of time. Listening to the outboards on You Tube was a big part of my decision in purchasing my 300 Verado. I found the 6 cylinder Verado to have a pleasing- not annoying/tiring sound. At idle it is virtually silent.
fourdfish	posted 11-13-2008 01:38 PM ET (US) How about a side by side comparison! I did have that chance and mine is quieter! Give me a break! Does it matter? BTW-- idle at 450 rpms! Cannot hear it at the helm!
alfred	posted 11-14-2008 06:40 AM ET (US) I know that you are asking about the 6 cylinder and I haven't heard one run, so I can't say how quiet it is, but I can say that not all of the 4 stroke 4s are the same. The 150 Verado is quiet, but when I have my boats side by side (Verado 150 and Johnsuki 140) and both motors running at idle, I can only hear the Verado, regardless of which boat I am in. The Johnsuki is really quiet. True it's 10HP less, but I don't think the 10HP makes much difference at idle. On the run, both seem about the same.
RJG	posted 11-14-2008 10:12 AM ET (US) I have been on all day, offshore fishing trips on boats powered by Suzuki, Yamaha and Evinrude. The 32 Twinn Vee was powered by twin 250 Suzuki 4 strokes. While dead quiet at idle, they wore me out during the long run to and from the fishing grounds. Not a high pitched sound just a loud, low pitched drone. The boat itself could have been a contributing factor as well as there being two motors. The 23 ft. Scout CC powered by a 225 Yamaha 4 stroke was again dead quiet at idle and also easy on the ears while at speed. A very quiet, low pitched drone that was easy to forget about during conversation but enough to listen to so as to keep in touch with the motor. My own 250 E-TEC is on a 23 ft. Hydra-Sport WA. Very quiet at idle but not as quiet as a 4 stroke. A subtle rumble that is just enough to hear but not so as to interfere with conversation. At speed she compares with the Yamaha as far as sound level. Easy to forget about but enough to keep in touch with through wind noise. The sound of an E-TEC at speed, to me, is one of authority. You just want to keep pushing the throttle further just to hear her go. And go she does. That big Hydra-Sport, with hardtop, will do 50+.
Peter	posted 11-14-2008 10:27 AM ET (US) The thing I notice between the 2-stroke and 4-strokes at speed is that the 2-strokes have a very well defined, everything in-sync sound signature. The 4-strokes at speed tend to produce a white noise type sound signature which I think is a result of valve train sounds and the combustion process sounds competing with each other making it difficult to "tune in". At speed I would not characterize the 4-stroke as being quieter but its frequency or frequency mix is clearly different.
swist	posted 11-14-2008 11:36 AM ET (US) Agree with Peter. 2-cycle engines, for the most part, have a more definite "pitch" (a chainsaw is the most obvious example). 4-cycle engines have much more a combination of frequencies. I will posit, however, that this difference may be lessening as 2-cycle DI engines get more complicated and have more parts and processes that contribute to the noise spectrum. And, yes, different people may react very differently to these various waveform spectra, in terms of perceived loudness, even if a decibel meter shows they are equal.
A2J15Sport	posted 11-14-2008 09:28 PM ET (US) We own two 75 HP Merc's on pontoons. One is 2-stroke, the other 4 stroke. As for noise, I can't tell. Their noise is different-period. Have I attached decibel meters-no. Neither is objectionable, IMHO. The biggest difference is: Starting and fuel economy. That's about it.
Lil Whaler Lover	posted 11-15-2008 07:51 AM ET (US) Try running both 2 strokes and 4 strokes on so-called rabbit ears and you will hear the difference. Starting the 4 strokes, an older Mercury 115 EFI and a Yamaha F-60 provides a very quiet exhaust, not unlike starting a car with a similar sized engine. When starting a 2 stroke, at least a 40 or larger and hear a sound that reminds me very much of a tuned pipe on a racing snowmobile. By the way, a tuned exhaust is necessary to optimize power/performance with a 2 stroke. The 2 stroke relies almost entirely on the water to silence it, where the 4 stroke is quiet anyhow. We have heard several times of trailer boaters pulling their 4 stroke powered boats and not noticing that they forgot to shut the engine off. I have never heard of this happening with a 2 stroke, most likely due to the rather loud "snort" of a 2 stroke out of water.
Peter	posted 11-15-2008 09:25 AM ET (US) If you run DFI 2-stroke that uses stratified charging on ear muffs you will also hear a difference relative to that tuned pipe -- pop, pop, pop -- sound a carburated 2-stroke makes. The DFI 2-stroke is much quieter, much smoother. That typical uneven, loud, pop, pop, pop sound you typically hear out of a 2-stroke running on muffs is non-existent in a DFI 2-stroke. Part of the reason is that the DFI 2-stroke isn't consuming anywhere near the same amount of fuel that the carburated 2-stroke is at idle on the muffs and the combustion has happened with the exhaust port closed. Also, the frequency of the exhaust sound between 2 and 4 stroke is different simply due to the number (frequency) of combustion events per flywheel revolution. The combustion frequency for 4-strokes that have the same number of cylinders as a 2-stroke is lower. For example, say we have two 115 HP 4-cylinder outboards both of which idle at 650 RPM. The idle exhaust pulse frequency for the 4-stroke is approximately 22 Hz and the exhaust pulse frequency for the 4-cylinder, 2-stroke is twice that, approximately 44 Hz. Even if the sound pressure levels for each were the same, because the human ear is "tuned" to hear the 44 Hz frequency more readily so than the 22 Hz frequency, the 2-stroke would seem louder even though objectively it is not. In other words, the sound pressure level at 22 Hz needs to be greater than at 44 Hz for there to be the same perceived loudness. See the equal loudness plot at www.phys.unsw.edu.au/jw/hearing.html for an understanding that the ear does not hear all frequencies equally.
seahorse	posted 11-15-2008 09:51 AM ET (US) there are dB stats out there, but I think the human ear is a better measuring device All the 4 strokes and the Evinrude E-TEC are very quiet motors, especially compared to your present one. Verado is supposed to be the quietest at idle, but a low hum or something similar is all you hear from any of them. At cruise speeds, a decible or so between them is hard to notice as the wind and waves make the most noise while you are on plane. Just remember that with any of the above engines you can have a normal conversation at the stern at any speed, and that's what counts.
kglinz	posted 11-15-2008 10:15 AM ET (US) I use a very simple way of comparing sound levels. Can I hear my VHF at cruise RPM? Opti = NO. 4 Stroke = YES.