PDA

View Full Version : Noisy boat -- Quiet boat


madrasahs
05-03-2004, 07:52 AM
Monday's Union Leader has an article on highway noise. Apparently, if highway noise exceeds 67dB, home owners adjoining highways can require the state to install noise barriers at no cost to the homeowner. (It's free tax money).

Lake Winnipesaukee, on the other hand, permits up to 86dB boat-exhaust noise in front of residences. That is louder than the state requirement for warning signals on boats. As Mr. Spock would say, "That's illogical".

By way of comparison, a quiet motorcycle's exhaust produces a noise of 67dB. A loud motorcycle's exhaust produces 86dB.

The noise/decibel measuring scale is logarithmic, so there's a reeeeeeeeaally big difference between 67dB :) and 86dB :( .

I find it interesting that boats featured in most Lake Winnipesaukee media publications are either artwork of sailboats, or photographs of sailboats -- not powerboats -- much less the ones associated with loud exhausts.


Can such relief from lake-loudness be far behind?


:confused:

http://www.theunionleader.com/articles_showfast.html?article=37029

Skip
05-03-2004, 09:39 AM
...Lake Winnipesaukee, on the other hand, permits up to 86dB boat-exhaust noise in front of residences. That is louder than the state requirement for warning signals on boats. As Mr. Spock would say, "That's illogical"...

Interesting interpretation of the rules governing audible warning devices. My review of the applicable regulations reveals that requirements (based on vessel size) is measured in detectable range, i.e. 1/2 mile or 1 mile....not decibel rating of the given device. For instance, I have never seen a decibel rating for a hand powered bell. Could you please direct us to the applicable regulation that details the state requirement for warning signals in decibels?

You also state that the 86db allowed for boat noise is much louder than warning signals. However the typical rating for an electric or air powered boat horn is approximately 110db (I have installed enough to know) and is many times more noisier than permissible engine noise (which is determined at a distance of 50 feet).

For the readers benefit, the 86db rating is an oversimplification of the regulation. RSA 270:37 divides boats into three categories, with a permissible 86db rating only for boats manufactured before 1977. Boats between 77 and 81 are permitted 84db, and all boats after 81 are permitted 82db maximum. As a comparison, the typical four stroke lawnmower engine produces 90db at an average distance of 50 feet. Being a logarithmic measurement, you can see that 82db is much quieter than 90db in apparent sound intensity...therefore the boat (if not tampered with) is much quieter than the average lawnmower.

The situation you have tried to make an analogy with (regarding the Union Leader story) is actually much more complicated than your post implies, all mistakes aside. :)

Gilligan
05-03-2004, 11:36 AM
... Interesting interpretation of the rules governing audible warning devices. My review of the applicable regulations reveals that requirements (based on vessel size) is measured in detectable range, i.e. 1/2 mile or 1 mile....not decibel rating of the given device. ...

I wonder if there is any definition of detectable in this useage. So far, this is a vague description. Can you hear the device (horn, bell or whatever) 1/2 or 1 mile away while the listener is in a quiet sailboat or a loud off shore boat? In calm weather or in a loud windy storm? What good is the sound from a whistle on a jet ski if you can't hear it over the noise of your own boat even at 150 feet or less? It may not be one of the lawmakers considerations. Maybe they assume that if it can be heard at all 1 mile away then it should be ample for an alert at 500 feet. Any idea?

Thank you Skip for researching these items and helping us all understand the rules. I always appreciate your posts.

Skip
05-03-2004, 12:25 PM
Hi Gilligan,

Thanks for taking the time to wade through some of my posts.

As you are probably aware, much of the boating regulations in New Hampshire (and any other State for that matter) are derived directly from the International "Rules of the Road" bible known as COLREGS.

COLREGS rules 32 through 37 cover sound devices, and New Hampshire basically follows COLREGS with minor modifications.

There is an Annex III to COLREGS that specifically defines the minimal db level required to reach certain distances. For example, a sound device being used to satisfy the 1/2 mile range notification distance would require a minimum db output of 120db as measured in 1/3 octave at a certain distance from the source. A one mile device would require 130db....both well in excess of the db level cited by the original poster.

One thing you need to be very careful of when using db is the source and type of measurements used. It can be very complicated stuff!

Anyway, there is no specification in COLREGS or NH law specifying requirements of the intended receiver. I think it falls under the general category of keeping a careful and proper watch.

Hope this helps some...my point in the original reply I made was to caution in using generalizations in comprehending regulations covering audible devices, regulations that can be easily confused due to subjectivity of the intended transmitter or receiver!

Skip

madrasahs
05-03-2004, 12:56 PM
"The situation you have tried to make an analogy with (regarding the Union Leader story) is actually much more complicated than your post implies..."

Yes, I am aware of that.

Decibel measurements are affected by temperature, humidity, elevation, distance, pulsing, -- even the "abruptness" of the sound.

I have used decibel meters in my profession (Bruel & Kjaer meters). Ten years ago, my last B&K cost $3000.

"As a comparison, the typical four stroke lawnmower engine produces 90db at an average distance of 50 feet."

There's one of the problems: Was that a typical new lawn mower -- or a typical old lawn mower? We're fairly familiar with quiet motorcycles and loud motorcycles, so that's why I used them.

"My review of the applicable regulations reveals that requirements (based on vessel size) is measured in detectable range, i.e. 1/2 mile or 1 mile....not decibel rating of the given device."

I agree -- and I agree with those requirements over dB ratings; however, decibel ratings can be located on the Internet for your particular signaling device.

Those numbers tend to change with the market, though. If one horn-manufacturer makes a claim for a 91dB horn, it does not take long for a competitor to claim 96 dB for his.

Interesting interpretation of the rules governing audible warning devices. For instance, I have never seen a decibel rating for a hand powered bell. Could you please direct us to the applicable regulation that details the state requirement for warning signals in decibels?

Again, I'd seek the Internet. My New Hampshire Boating Guide-conforming signal device (my ACME "Thunderer"), was rated at 78dB last season, so I bought an ACME "Tornado". The "Tornado" is now rated at 125 dB (up from last year). It takes more lung-power to make 125 dB, but either will make one's ears ring.

You also state that the 86db allowed for boat noise is much louder than warning signals. However the typical rating for an electric or air powered boat horn is approximately 110db (I have installed enough to know) and is many times more noisier than permissible engine noise (which is determined at a distance of 50 feet).

Well, I didn't write "all" warning signals. I personally own an air horn rated at 130dB (J.C. Whitney) :).

My experience is mostly with boats that truly need them -- boats whose skipper's survival depends on being heard over the ambient noise environment. An exhaust producing 86dB will drown out my "legal" ACME "Thunderer", but maybe not my "Tornado".

"...all mistakes aside. :)

I'll try to be more accurate....