Trying to reduce the engine noise

[DBamaC]

Like pretty much everyone else, I think our boats are louder than I'd prefer. I want to do some real sound deadening in the future, but have other priorities at the moment.

The other day I was grabbing something at my local Lowes and saw a marine seal product for $8 a package. I figured all I had to lose was 8 bucks and 10 minutes so I bought a package. I put it around the engine hatch, leaving a small opening at the area half way between the hinges.

Before at full throttle, I couldn't hear the stereo and couldn't talk to my wife sitting in the port rear seat. Now, though it's still loud I can hear the stereo and yell back and forth with the wife. Definitely a nice stop-gap mod. I'm guessing it dropped the sound 3 db or so. I think before this weekend I'll do the same with the gas tank cover and see if it helps any.

 

[njmr2fan]

Interested. More info please. I wanted to do a major sound deadening project over the winter but every little bit helps.

 

[WickedPorter]

I put a foam (1" thick) backing on the underside of the fuel hatch, and also added some extra gasket material around the engine hatch. I didn't notice much difference. I believe most of the engine noise comes from resonance from the motors through the hull. I'm wondering if an upgraded / enhanced motor mount might help a bit more than all of these insulating projects ... countless threads on various forums about adding a bunch of sound-deadening material on various parts, but I haven't really heard of any significant results from any of this, myself included.

ETA: There was a little difference. I'm just not sure it was worth the effort. I suppose every little bit helps!

I used the following material: http://www.mcmaster.com/#5692t49/=yn55jf

 

[njmr2fan]

great information, but what kind of foam? Is it fuel and heat proof? Where did you locate it? Where can the foam that Yamaha is using be found?

 

[billyb]

You are not going to be able to REALLY reduce the noise. My readings were like three dbs less after my project was done, but...like @DBamaC said, it sure SEEMS quieter.

All I did was to put the bulb seal around the hatch, then put some decent sound dreading stuff on the fuel hatch. Like I said, seems a little quieter.

Stuff I still need to do, bulb seal the fuel hatch and put the remainder (2-3 strips) of my sound dreading stuff somewhere in the engine compartment. Once that is done, if it drops a few more dbs, I may buy another batch of ten strips for $70.

 

[WickedPorter]

Try this stuff... I wonder if adding a bunch of this to the engine compartment would help. http://www.mcmaster.com/#5692t49/=yn55jf

 

[billyb]

This is the stuff I used, it's thick and easy to use/apply.

 

[njmr2fan]

If a waterproof, acoustical, eggcrate style foam could be applied inside the the rear swim platform where the muffler sits, that area would quiet down. The same is true for a few small hard areas inside the engine bay and to the sides of it behind our aft seating areas. Any hard surfaces will resonate with engine and exhaust noise and become a type of "speaker box". Using various types of materials (spray on, expanding foam, and sound deadening foam I quieted down my Toyota MR2 to Lexus standards, probaby better. Some of those products are unavailable, some would not stand up to a marine environment. If I could figure out the supplier of the current materials I think I could do a lot to quiet down the boat. 3-5 dbls is a big decrease in sound for our ears don't forget.

 

[Bill D]

@DBamaC Sounds like you need a better stereo.

 

[Britboater]

Fitting the carpets reduced engine noise on my 190.

 

[DBamaC]

@DBamaC Sounds like you need a better stereo.

I'll be directing the wife to speak with you. You make a lot of sense.

 

[njmr2fan]

Oh man, quite the contrary in our case. The dude who sold me this boat had just put in a 1200 watt Rockford Fosgate 6 speaker 2 amp stereo that sounds amazing. (I get in trouble for cranking up AC/DC while me and the kids play air-everything ) she just wants some peace and quiet while on the water so we can relax....

Doesn't much matter that that's how I relax....

 

[Bill D]

Haha, @njmr2fan I just put the wife up in the bow and turn those speakers down a bit. She might keep complaining, but if I go fast enough / play the music loud enough I can't hear her anymore. I guess that's the good part of not having any kids.

 

[DBamaC]

Like pretty much everyone else, I think our boats are louder than I'd prefer. I want to do some real sound deadening in the future, but have other priorities at the moment.

The other day I was grabbing something at my local Lowes and saw a marine seal product for $8 a package. I figured all I had to lose was 8 bucks and 10 minutes so I bought a package. I put it around the engine hatch, leaving a small opening at the area half way between the hinges.

Before at full throttle, I couldn't hear the stereo and couldn't talk to my wife sitting in the port rear seat. Now, though it's still loud I can hear the stereo and yell back and forth with the wife. Definitely a nice stop-gap mod. I'm guessing it dropped the sound 3 db or so. I think before this weekend I'll do the same with the gas tank cover and see if it helps any.

Here is the product...

 

[Eurocat]

Has anyone tried to put soundproofing material on the lid on the cleanout port? I was standing by the rear seat while my wife was driving the boat and it just seemed most sound came from there. (I think the actual jet moving is louder than the engine when at speed).
Just a thought...

 

[njmr2fan]

I agree. The empty transom area contains the muffler and sits atop the jet. My plan is to stick some type of sound absorbing foam in that area to reduce the sound (think sub box) effect in this area. this will greatly reduce the amount of sound being fed into the rear under seat storage and passed up through the hull spaces forward.

 

[Ronnie]

So I've installed a lot of sound absorbing material in the sx230ho I had and the 242 ls I have. I did the complete engine compartment on both boats, all the hatches on the sx and the fuel hatch on the ls. Most of it came from west marine or McMaster Carr. For reference, Searay uses hush cloth/foam in its quiet ride system and you can get it form McMaster Carr but you have to call for it since it is not labeled as such online. The material I used varied on the six from1/8" to 1", the 1/8" stuff was only used in the hatches not the engine compartment. On the 242 I used 1" thick material the first time around and added another 2" to some of the areas in the engine compartment. I also added pipe insulation to the engine hatch opening on the six and bulb seal to the 242. In neither case was it easy or cheap.

Here is what I think, based on observation not decibel meter readings:

1. In both instances there was/is a noticeable reduction.
2. The reduction is more noticeable in the sx, I suspect that is because the engines in the sx max out at 10,200 whereas the engines in the 242 max at about 7,700. This stated, there is a high pitched noise that the sx engines make at about 9,000 rpm and up that the 242 does not make at all. I believe that the sound absorbing material really helped to reduce or eliminate this high pitched sound in the sx.
3. For me the effort was worth it on the six but not the ls. The ls is quieter to begin with but I'm comparing it to a few years on an sx. Again there seemed to be a reduction in the ls but I could have lived with it as it was based on my experience with the sx pre and post modification.

Misc. notes:
1. If you buy from McMaster Carr you have access to all the materials specs (e.g. Sound absorbing performance, whether it is fire and/or water resistant, etc.).
2. Putting material in the compartment under the cleanout hatch area is a good idea it is also much harder than putting it in the engine compartment, especially in a 242. Access is limited because of how high the lip is and how low the hull is. There are also a lot of plumbing obstructions that are not just hard to get apart but harder to put back together.
3. By adding 2" material on top of 1" material I was trying to emulate what I though Yamaha did on the 2015 240s. However, in addition to using thicker foam Yamaha also filled some of the free/speaker box area over the engines by putting storage compartments there. They also changed the material that the engine to shaft couplings are made of and others say some of the engine components have been redesigned or made of new materials as well.
4. I've read here that a 3db reduction equates to a 50% reduction in volume. I'm sure I did not get a 50% in the six or ls.

 

[dandjwest]

Just bought a used SX190 this fall and am on the steepest part of the learning curve. I have spent 30 years with I/O drives. Our boat is on a rocky, shallow Adirondack lake with a highly variable water level, season to season.

Noise reduction is high on my list. Different engine and propulsion mounts sound like a good idea. Eliminating resonances also sounds key. One thing I have noticed is that when the steering is cranked full port or starboard at lower engine speeds, one of the major resonances heard from the pilot's seat stops. I am assuming there are steering and throttle control cables from that area to the engine and propulsion unit. Does anyone offhand know if my assumption is correct and how the cables are run? Has anyone looked at the cable contribution to hull resonance?

 

[njmr2fan]

@dandjwest I know I had the square lid off of the gas tank storage compartment and saw 3 cables just lying there bundled together and stuck them inside a foam pool noodle to eliminate much of their vibration.

 

[dandjwest]

Had not explored this area yet. I'll look at it the next time up, though it may be spring as the boat is out for the season. Thank you.