Quieting Boats down

[Tim_Duggan]

My TD 21 pipes on my hydros are loud, although below the limit, I asked Dave about future add on stuff, and Im sure he will accomodate us....

Dave is the man, Im sure he'll develop functional pieces in the future to help us out......... good luck... Mike

Paul Osmond used a modified SPP TD21 at the NAVIGA world champs and finished 4th in the finals.

At an event in Sydney Australia this weekend, SPP muffled pipes finished first, second and third in 21 hydro.

 

[AndyBrown]

I've been to the NAVIGA Worlds four times. Twice world champion.......and helped a lot of poeple achive the same status. Not an easy thing to do!

When I go there I run the same 60%-70% nitro, the same engines, the same props and the same pipes with some extra muffling. There are ALWAYS TWO db meters on the pontoon at the worlds. They average the two, if there is any question. I've never been warned for being over the NAVIGA limit, which I believe is 82 db. Al Hobbs has gotton warings while using the standard MACS muffled pipe, which is a fairly quite pipe.

I can build an add-on that will get you guys to where you want to be. I didn't say anything about 90 db.

SO...... I guess I'm offing a way to 'quiet boats down'.......I think it is relevant to this thread.

Andy, I was told by John that the pipe he had on hid forty boat was the pipe used in the worlds by you. This pipe did have an fiberglassed on extra muffling device. Was this the pipe that you we under 82 dbs wwith? I am curious because it was 86 to 88 dbs every pass that I was not in John heat because I particually watched the meter because of the above information. Would you have done anything differently to your boat to address noise than was done on johns boat?

Allen

Yes, that was my back-up pipe. I guess 86-88 is not so bad at an event where many boats could'nt get under 92.

John's 67 boat was over 92.......he called me, I told him how to make a quick fix......he did it and was good for the rest of the week. B)

 

[Mike Larson]

Hey Tim! Thats good info on SSP..... Dave's pipes rock, all that run em know.... Im hoping to take my boats quieter yet, though, ( I have a feeling the legal levels will continue to drop until they ( public) force us out...... I run concrete cutting equipment daily, and, the noise from my SSPs doesnt phase me, but my freinds often plug their ears around me like the higher range spectrum is hurting their ears (?) High modded 21 novas/td21 muffled and short...... IMHO Daves got the pipe thing goin on, Andy's helpin out also, we'll all benefit eventually, like J knight stated, its gonna take time....... An add on muffler will be a lot more financially feasable for Tommy toenails boater, Christ, I cant afford a DB yet! Kudos to the pipe guys standing up to the plate! Mike

 

[AWaddle322]

I've been to the NAVIGA Worlds four times. Twice world champion.......and helped a lot of poeple achive the same status. Not an easy thing to do!

When I go there I run the same 60%-70% nitro, the same engines, the same props and the same pipes with some extra muffling. There are ALWAYS TWO db meters on the pontoon at the worlds. They average the two, if there is any question. I've never been warned for being over the NAVIGA limit, which I believe is 82 db. Al Hobbs has gotton warings while using the standard MACS muffled pipe, which is a fairly quite pipe.

I can build an add-on that will get you guys to where you want to be. I didn't say anything about 90 db.

SO...... I guess I'm offing a way to 'quiet boats down'.......I think it is relevant to this thread.

Andy, I was told by John that the pipe he had on hid forty boat was the pipe used in the worlds by you. This pipe did have an fiberglassed on extra muffling device. Was this the pipe that you we under 82 dbs wwith? I am curious because it was 86 to 88 dbs every pass that I was not in John heat because I particually watched the meter because of the above information. Would you have done anything differently to your boat to address noise than was done on johns boat?

Allen

Yes, that was my back-up pipe. I guess 86-88 is not so bad at an event where many boats could'nt get under 92.

John's 67 boat was over 92.......he called me, I told him how to make a quick fix......he did it and was good for the rest of the week. B)

I think it goes further to prove that meter calabration is going to be important.

Allen

 

[Don Ferrette]

I think it goes further to prove that meter calabration is going to be important.

Allen

Agreed. I think that once that happens most of this ruckus will go away............... :blink:

 

[AndyBrown]

I think it goes further to prove that meter calabration is going to be important.

Allen

Agreed. I think that once that happens most of this ruckus will go away............... :blink:

Yep! I agree on that too, Allen

 

[waltr]

I ran a bunch of boats yesterday.The largest being only my 45 SGX.But the adverage was 86 db.My 45 SGX was at 86db too.

Last week when my Mac powered 21 Seaducer was run,it was @96-97db with a Parabolic fat pipe. With some foam inside the boat and a odd add on muffler,it was also at 86db yesterday. Calibrated or not,I still see a 9-10db improvement and obviously could hear it too.

Probably had all of $30 to get the seaducer that quiet and just a little effort.

This is the muffler on my SGX.

It's baffled inside.

Anybody know who made it?

https://www.intlwaters.com/gallery/displayimage...10208&pos=0

 

[Brian_Nelsen]

waltr

Those are good results thanks for the post.

Brian

 

[mark voorhies]

I ran a bunch of boats yesterday.The largest being only my 45 SGX.But the adverage was 86 db.My 45 SGX was at 86db too.Last week when my Mac powered 21 Seaducer was run,it was @96-97db with a Parabolic fat pipe. With some foam inside the boat and a odd add on muffler,it was also at 86db yesterday. Calibrated or not,I still see a 9-10db improvement and obviously could hear it too.

Probably had all of $30 to get the seaducer that quiet and just a little effort.

This is the muffler on my SGX.

It's baffled inside.

Anybody know who made it?

https://www.intlwaters.com/gallery/displayimage...10208&pos=0

Looks like a Prather?

 

[waltr]

I thought the Prathers were straight through.

This one's baffled inside.You can't look through it.

There are 2 very small openings about 90* apart

that shine 2 light spots through inside.

 

[Rigged]

I thought the Prathers were straight through.

This one's baffled inside.You can't look through it.

There are 2 very small openings about 90* apart

that shine 2 light spots through inside.

the prather is straight through (im looking at mine now).. that one looks like it could have been a prather at some point in time, and was modified?

 

[Ian Folkson]

Our noise limits are going up slowly and we warned all teams that at the next Naviga we are going to clamp back down on noise.

Our chief judge has to be given the noise readings from every first heat at a venue that is new to us so he can decide the limits for each class. He makes allowance for the other boats running and if the lake is surrounded by trees or hills the base limit has to go up.

After all the first runs the majority of boats in the 91 class were under 85dba while running in the heats.

So the limit was set at 85 + 1 allowance. Boats over this were given warnings and some disqualified. we had boats at 90db but to the ear sounded quiet this is the problem of noise readings but the meter is used and not the ear so everyone has an even playing field.

My own 91 endurance boat was during testing read at 83db by one of our team using a cheap hand held meter costing no more than $65.

On the more expencive meter used at the competition I was also 83db so most clubs can afford a meter to check there boats and get a good idea if they are under the limit. I keep my boats quiet after getting disqualified after a good heat at naviga in 1992. I have since then always run a fully enclosed boat. I use different grades of rubber mounts to get the noise down and of course quiet pipes..

Here are the rules we are using for Hydro in Naviga

7. Methods for measuring noise levels in the FSR category

7.1 General

(1) The measurement microphone must be positioned as follows:

- Height 1000 mm approx. X 200 mm above water level

- Position 25 meters to the right for FSR-V and to the left for FSR-H at the right angle to the centreline of the FSR course and 22 meters away from the line connecting the two lowest buoys.

- The measurement microphone must be shown at right angles and with the connecting line of the two lowest buoys and securely attached.

(2) It is not necessary to pass the noise measuring equipment at full speed.

(3) Faults with a silencer which cause excess noise level must be corrected immediately. The model must be taken off the water on completing the commenced lap, failing which the competitor will be disqualified.

7.2 Measuring methods in FSR-H classes

(1) At least one noise measurement must be taken for each model during the race, under the following conditions:

- There should be no other boat within 15 meters around the model being measured.

- The noise measurement must be taken when the boat is on the base line at least 15 meters away from the microphone.

(2) When more than one measurement is taken, the recorded noise level will be the average of all measurements.

(3) The competitor must be advised immediately after the first race if their boat exceeds 80dB/A. If after the second race the boat still exceeds the noise level they will receive a warning and if during the third race the noise level is exceeded they will be immediately disqualified.

Ian Folkson Naviga FSR V representative

 

[waltr]

I thought the Prathers were straight through.

This one's baffled inside.You can't look through it.

There are 2 very small openings about 90* apart

that shine 2 light spots through inside.

the prather is straight through (im looking at mine now).. that one looks like it could have been a prather at some point in time, and was modified?

Nope,the muffler was never modified

 

[waltr]

Ian,

How hard are you guys laughing at us over there.

It's something you've all gone through before over there.It's nothing new.

There are a few from accross the big pond that have given us great advise as how to quiet down.

Tips on pipes,stuffing boxes,cowls,motor mounts,insulation and more.

Also copies of your governing rules etc....

I'd like to thank them and you for your help with this problem.

You'd figure by now,most would have absorbed the tips.Guess not.

All of the answers are just about cut and dry.You guys have has noise restrictions for about 15 years now and delt with them.

Eventually we will too.

This BS over here just baffles me.

I guess you can lead a horse to water,but you just can't make him drink it. <_<

Thanks again for sharing your rules with us.

A select few are actually listening.

 

[Marc Paulais]

My 47" Seaducer was tested at 79/81db at the last Naviga WC in Norway. No fancy setup to reduce noise: Speedmaster motor mount, rudder and strut. Seaducer cowl and pool noddles on the sides. CMB 91RS with CMB long pipe.

And I could surely get a lower noise level by covering the entire pipe...

My two cents.

Regards

Marc

 

[AWaddle322]

Our noise limits are going up slowly and we warned all teams that at the next Naviga we are going to clamp back down on noise.

Our chief judge has to be given the noise readings from every first heat at a venue that is new to us so he can decide the limits for each class. He makes allowance for the other boats running and if the lake is surrounded by trees or hills the base limit has to go up.

After all the first runs the majority of boats in the 91 class were under 85dba while running in the heats.

So the limit was set at 85 + 1 allowance. Boats over this were given warnings and some disqualified. we had boats at 90db but to the ear sounded quiet this is the problem of noise readings but the meter is used and not the ear so everyone has an even playing field.

My own 91 endurance boat was during testing read at 83db by one of our team using a cheap hand held meter costing no more than $65.

On the more expencive meter used at the competition I was also 83db so most clubs can afford a meter to check there boats and get a good idea if they are under the limit. I keep my boats quiet after getting disqualified after a good heat at naviga in 1992. I have since then always run a fully enclosed boat. I use different grades of rubber mounts to get the noise down and of course quiet pipes..

Here are the rules we are using for Hydro in Naviga

7. Methods for measuring noise levels in the FSR category

7.1 General

(1) The measurement microphone must be positioned as follows:

- Height 1000 mm approx. X 200 mm above water level

- Position 25 meters to the right for FSR-V and to the left for FSR-H at the right angle to the centreline of the FSR course and 22 meters away from the line connecting the two lowest buoys.

- The measurement microphone must be shown at right angles and with the connecting line of the two lowest buoys and securely attached.

(2) It is not necessary to pass the noise measuring equipment at full speed.

(3) Faults with a silencer which cause excess noise level must be corrected immediately. The model must be taken off the water on completing the commenced lap, failing which the competitor will be disqualified.

7.2 Measuring methods in FSR-H classes

(1) At least one noise measurement must be taken for each model during the race, under the following conditions:

- There should be no other boat within 15 meters around the model being measured.

- The noise measurement must be taken when the boat is on the base line at least 15 meters away from the microphone.

(2) When more than one measurement is taken, the recorded noise level will be the average of all measurements.

(3) The competitor must be advised immediately after the first race if their boat exceeds 80dB/A. If after the second race the boat still exceeds the noise level they will receive a warning and if during the third race the noise level is exceeded they will be immediately disqualified.

Ian Folkson Naviga FSR V representative

Ian, so tell us more about the meter, its calabration and time intervals for calabration.

One more question. On these super quit pipes do you all use pipe pressure?

Allen

 

[Ian Folkson]

Allen

I have one of the ones that radio shack sells . Type in Sound meter and the cheapest one that comes up at $44.99. I have had it since the 80s when I first found out about rubber mounts. I had it calibrated by a calibrater the Model Power boat association bought with a better quality meter. I have not had it done for years but it still gives a reliable guide to the noise the boat puts out and as i said one exactly the same gave the same readings as the expencive one used at the naviga champs. One of the noisiest things our boats have after you have addressed the noise from the pipe is the carb induction roar hence fully covered boats. The other major factor in mono boats is the hull resonating which can be cured with bulkheads and reinforcement to stop the drumming. In hydros the noise from the wooden boats is less there the noise is pipe and carb and some transmitted noise from hard rubber mounts to the tub. Another major finding was that thin carbon engine mounts also reduced the noise and seemed to prevent so much engine breaking. One thing a lot of people do is make the carbon engine mounts too thick. I have a set in my 91 that are made from carbon angle only 2mm thick. these flex as well as the rubber mounts when you push the engine. I have used these type for over 10 years and they are still in good condition.

As Marc said if you use the long silenced pipes you will be on your way to quieter boats.

Ian

 

[DaveMarles]

Getting back to the original question. My 2 eurocents. Any tuned pipe can be quietened down without powerloss but an add on stinger muffler is not going to cut it unless its huge. Eventually all the pipes used there will have real silencing chambers on them, better get used to that idea.. If you use an internal stinger you must increase the id slightly over a normal optimised short external stinger or there will be an increase in backpressure and pipe temperature. Internal stingers on their own are not going to reduce the noise level appreciably. You must be realistic, its a quick fix but its no good getting the boat just under the limit at one race. Next time it could be over because no matter how the meter is calibrated or set up or take care over the method of measurement the noise measurement will NEVER be exact. Better to be sure and then there is no need for arguments.

Rubber mount the pipe in some way. If you have a noise problem then try and cowl the engine and pipe. Its possible on any boat and will reduce the noise coming from the pipe itself not just the outlet. Make sure the cowl is a good fit around the edges especially around the carb area as there is lots of noise from .67's upwards from the carb. Using soft rubber mounts with an aluminium cup over them reduces the harsh sound from the motor without allowing it to move around too much.

Dave

 

[AWaddle322]

Ian and Dave,

Thanks for sharing your imput. I know this thread is not specifically for me but I have all the things that you all mention for noise. When it comes down to it the only place that I still have left to quiten my boats down is out the exhaust. Would you all mind maken some quite pipe recommandation for 67 and 80 riggers? Anything about particular pipes. Where to purchase them? ETC?

Thanks,

Allen

 

[Stuart Barr]

I recently tried a new style of add on muffler that I had Steve Cooper make. Found that it took my system (CMB 80 w/67-80 big belly pipe) from 95db down to 89db. Performance results were VERY good. Steve is making a slight change that I suggested and will let you know in a few weeks.