FSH 210 Soundproof

[FSH 210 Sport]

I attached an Excel file containing my data.
I hope it is self explanatory.

Hey TG,

I was chatting with a friend of mine who has some experience with sound deadening via his friend who has a marine business doing just that. I told him about your results and provided him with your spread sheet.

We both agreed that your db meter appears to have some issues since the phone app showed consistent results across the board.

The other thing he mentioned that his associate found was that materials such as sound down reflect the sound, however, the sound will in essence bounce back into the chamber where it was created, so one needs to have materials in that area that will absorb sound. So you can put sound deadening material like sound down on the bottom of the engine hatch and the bottom of the storage compartments adjacent to the engine hatch, but, some material like the egg crate foam has to be installed in other areas of the engine bay, like the sides of the engine bays as if you have opened those storage compartments while the engine you know how much extra sound comes out, to absorb the reflected sound, of course in addition to making sure the sealing surfaces are properly gasketted. He told me his friend would put egg crate type foam onto to canvas and put that in the bottom of the engine compartment under the engines to help absorb sound waves. There is also a material that he told me about that looks like egg crate material but it is coated so that it will not absorb water or other stuff so you can wash down the bay without it getting soaked. I’m checking to see if I can find that material right now.

I think that when I do this project I will put the sound down material on the bottom of the engine bay hatch, the storage compartment lids, the clean out hatch and the front of the engine bay. Then egg crate type material will then be put under the engines, on the sides of the engine bay, on the walls of the aft storage compartments and anywhere I can put it in the aft bilge. The whole engine bay an aft bilge are like one giant bass drum that sound will just reverberate in.

 

[FSH 210 Sport]

Here is the sound absorbing material.

Quiet Board™ Acoustic Panel 1" (Case of 13) - Soundproof Cow

Quiet Board™ acoustical panels are an excellent solution for areas that need noise reduction. Great for marine, food service, & more.

www.soundproofcow.com

It looks like it’s expensive but that’s a case of 13 eight square foot pieces. Have to see if they’d sell it in smaller quantities

 

[Jerlane]

FWIW, as I mentioned previously, the installation of the Skat Trak impellers reduced the perceived sound by 50% alone at best cruise.
[/QUOTE]

I'm curious about these. If they really made that big a difference wouldn't everyone here be all over them? I'm not doubting you, I just wonder why there hasn't been more discussion on this? Maybe there has been and I just haven't seen it. Are they even in business anymore?

 

[FSH 210 Sport]

FWIW, as I mentioned previously, the installation of the Skat Trak impellers reduced the perceived sound by 50% alone at best cruise.

I'm curious about these. If they really made that big a difference wouldn't everyone here be all over them? I'm not doubting you, I just wonder why there hasn't been more discussion on this? Maybe there has been and I just haven't seen it. Are they even in business anymore?
[/QUOTE]

Sadly Skat Trak got out of the personal water craft impeller business.. looks like they are just selling paddle tires now. My hunch is that they were not being profitable in their US made impellers and competing against the chinese made Solas impellers. You may be able to find the Skats on someone’s shelves somewhere, and if you do not need the extreme high altitude re pitching you will be in great shape. For me the problem I had was that base pitch is a bit too high to have them pitched for the high altitude use I wanted, and they went out of business before I could get a lower based pitch from them. Although I’m going to be testing my recently re pitched set tomorrow. I originally bought my skats from impros and had impros pitch them for high altitude and they could only get so far with them, but since Leading Edge came on the scene I sent them to LE and they were able to modify them a bit more.. nothing to loose there as they were just sitting on the shelf, so fingers crossed, if I can get 500 rpm more out of them then they will be in the range I need.

As to the why people have not experienced the results I had with the Skat Traks being quieter, well, have a look at the second sentence in the above paragraph, most people were not willing to pay another $100-150 per impeller for the Skats. I try and buy American made products first as I try and support American businesses. So in my case, I ended up using the Solas Dynafly impellers because I could not get a low enough base pitch to accommodate my high altitude needs with the skat Traks due to them going out of business.

It appears that Yamaha figured out that there was significant sound reduction available by going with the four bladed impellers on the 2024 model year boats with the 1.9 L engines though as well as reduced vibration. Some engineer must have figured out that a lot of sound was coming from the pumps. And when you think about it, the engine compartment and the aft bilge compartment is like a big bass drum, and all that sound from the engines and pumps is resonating in that space. I’m hopeful that the re pitched again skats will work for me and then add sound insulation to both the engine bay and the aft bilge and perhaps achieve a 6 DB reduction in sound which is probably highly optimistic but if possible will be amazing, that will put the sound level at or below modern outboard engine noise.

I’m as methodical as possible when testing things, I learned this from jetting Kehin FCR carbs on dirt bikes, and from testing suspension on dirt bikes. So when I started testing impellers for high altitude for my boat which was suffering from too much pitch and not enough horsepower due to altitude loss, I made sure to duplicate the test conditions and record performance and conditions, the sound thing came on the first test of the skats and I turned to my friend and said, “is it me, or is the boat a lot quieter with the skat impellers?”, he said, “its not you, they are much quieter”. He then got up and moved around the boat and said there was a lot less vibration as well. So right then I checked the App Store and found a DB meter for my phone, used it to check the sound level and recorded the reading. Then I added that to the rest of my testing and confirmed that the skats were either at or close to a 3 DB reduction in sound over the OEM and Solas impellers which is a halving of the perceived sound. Not many people are willing to spend the time and money to test various configurations to make things as best they can. Throughout my life I have always endeavored to do and or be the best at what I was doing, whether that was my career, making rifles as accurate as possible, racing dirt bikes or shifter karts. A lot of people will accept “good enough” and that is what delineates the very successful from the not as successful. My shifter kart racing mentor put it this way, “do your home work and you will be successful”. He was right!

 

[FSH 210 Sport]

Today I was testing the skats, they are so much quieter and smoother than my Solas impellers and I could not get them to break away, but, sadly, I can only get 7100 & 7200 rpm from them in cool air. The solas would have had the engines at 8000 rpms.

I measured the sound with my phone app db meter near my ears which to me makes the most sense, but for the heck of it I also measured where @TeenGee measured. Near my ears at idle I recorded 77 db, and on the small shelf it was 79 Db. At best cruise roughly 6100 rpm near my ears I recorded 87 Db and 89 Db on the small shelf.