Various sound readings

[buckbuck]

This past season I took some sound readings from some Yamaha boats. Each sample was taken with the windshield closed and holding the instrument near the left ear of the driver. Attached are results. Picture is of instrument. Please note the 2008 212X and 2007 AR230 have been modified to try to deaden the noise.

 

[jawsf16]

@buckbuck
Tell your wife unfortunately you HAVE to buy a new 212x, for health reasons of course.

 

[swatski]

@buckbuck Great topic!

What I'm puzzled by is the discrepancy between your table and the boattest.com, especially for the 2015 242. Was the one in your test the new model w/"quiet cruise" factory mods?
88dB (boattest) vs 102dB (in your table) is a HUGE difference...
I am not super impressed with that new quiet ride, but my 2016 240 is much quieter than the 2012 190 stock. I'm actually in the process of planning my sound deadening strategy, so I am VERY INTERESTED in your thoughts.

Here is your table:


And boattest's (2015 242 Limited S):


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[jcyamaharider]

Hey Jim, bring that to Shelbyville so I can see how many DB's my stereo pulls....LOL

 

[MattFX4]

That is pretty big discrepancy. I think my 15 242 is fairly quiet. I have had other jet boat owners on board and they were impressed how much quieter it was compared to older boats.

 

[Gym]

It is important to note that @buckbuck's readings were on the db scale and the boat test readinds were on the dbA scale (dbA means the A weighted scale which is adjusted to accommodate the sensativity of the human ear). That may account for some of the difference. Also equipment calibration may also account for some variations. I think @buckbuck's readings were relevant for the test he performed as he used the same equipment between the different boats and I'm assuming on the same day in the same body of water. Just to add some perspective here...The normal human ear can only detect a noise level change of 3db. Anything less is considered imperceptible.

 

[swatski]

It is important to note that @buckbuck's readings were on the db scale and the boat test readinds were on the dbA scale (dbA means the A weighted scale which is adjusted to accommodate the sensativity of the human ear). That may account for some of the difference. Also equipment calibration may also account for some variations. I think @buckbuck's readings were relevant for the test he performed as he used the same equipment between the different boats and I'm assuming on the same day in the same body of water. Just to add some perspective here...The normal human ear can only detect a noise level change of 3db. Anything less is considered imperceptible.

Excellent point! I thought it must be something like that, why I was asking for clarification.

If that is the case, whoever performed the sound deadening on the two boats equipped with it - did a darned great job! Basically, beating the Yamaha quiet cruise technology. That is no small feat, considering that Yamaha uses new redesigned drive shaft couplers and polyurethane foam injections inside the "pseudo-double hull" to quiet the new boats.

I wonder what specifically was done, is it one of the older sound deadening threads?

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[buckbuck]

I guess I should have added a bit more info initially.
2008 212X is mine, @buckbuck
2017 212X is @Brian eilrich
2015 242LS is @OperationROL
2007 AR230 is @JCampbell

The 2) 212X boats were compared on the same day. The other 2) boats were compared on a different day but at same time. It is possible @OperationROL numbers were skewed as I wrote them on a napkin after he reported them to me. They seemed to be off because my perception is his boat is noticeably quieter than mine.

The instrument is old and has not been calibrated. It does, however, provide a reasonable comparison between the models. (That new 212X keeps begging for my attention)

I wish I knew what you guys know about decibels and how to justify the numbers I am seeing and those done by boattest.

Every year for the last 8 years I have been doing things to try to quiet my boat. I think the most effective thing was to stuff all the holes between the engine bay and the rest of the boat. I used foam insulation that the pipefitters use to blanket the big chiller and cooling tower lines. I also provided foam bulkheads under the seats to keep the noise from traveling forward.

@swatski I know you are a testing type guy so if you are interested I could send this instrument to you to do better research. You could go out with the St. Lunatic friends and test their boats.

 

[JCampbell]

My boat is no where close to stock for the sound deadening. The work I did this year had the largest impact at lowering the dB. Also my readings were without ballast. The boat does get quieter with ballast. The "resonating tube " gets filled with the bags.

 

[Julian]

Also, if Neil (@OperationROL ) was holding the meter next to his ear....it would have been much higher and perhaps more in the wind!

 

[Bruce]

I happen to have the same Radio Shack decibel meter that I have seen in the Boattest videos. If anyone wants to assemble a group of boats I could ship (loan) it to you for testing.

 

[Gym]

I think these tests are valid within this test group using the same meter. You are certainly able to determine which is the quieter boat or which improvements gave better results. My earlier point was just that there would be no fair comparrison with the Boattest readings whereas they were using different equipment, different dB scale and different boating conditions.

 

[swatski]

I also provided foam bulkheads under the seats to keep the noise from traveling forward.

@buckbuck I think that is one of the most important components. Now that I think about it, that is missing in the new boats -- there is a noticeable increase in engine noise if the STBD storage compartment is opened (while running).

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[robert843]

Cool test! I'm trying to figure out how the 2017 got quieter at 50 mph then it was at 26 mph that's crazy.

 

[OperationROL]

I am now just seeing this post for the first time. I do believe my boat is significantly quieter than the others so I believe we may have an issue with consistent testing environment and procedures. Next spring, we will have to conduct the tests a little more scientific. Perhaps we can make some type of stand so that we can guarantee that the sound meter is in the same place on each boat, etc.

 

[Gym]

Cool test! I'm trying to figure out how the 2017 got quieter at 50 mph then it was at 26 mph that's crazy.

Cause when you're going faster than the speed of sound the sound is behind you.

 

[buckbuck]

@Bruce Have you ever tested your boat with your meter?

 

[Bruce]

@Bruce Have you ever tested your boat with your meter?

I want to but have never done so. I have performed some tests on stereo upgrades.

 

[seadude]

Bimini top up or down makes a big difference also (and one disadvantage of the large e-series top)!

 

[buckbuck]

That is a good point. I should have noted that none of the biminis were deployed during the testing.