Another nonsense topic from the dark side......Generator noise

[Ronniesonic]

I am surprised Bizzard has not had the foresight to invent a 'genny bass bin'? A weather & more sound proofed housing, designed to emit less higher annoying frequencies?

 

Low frequencies (LFO) do it for me. Those huge homemade bassbins the Reggae'Soundsystems' created were awesome.

 

However, complaints on the cut would mutate from 'decibels' to 'vibrations'.

I wonder how the darkside would cover these?

 

'Vibrators on the towpath upsets the rabbits!'

[Sir Nibble]

Can you not buy electric gennys?

 

They would be quieter.

 

The new breed of F1 cars have a thingamajig that creates and stores electric power through breaking and the revolving of the wheels, I think.

 

Could we have something in addition to the alternator to do the same from the prop shaft?

 

Martyn

I'm sure you must have tongue firmly in cheek here. Don't you?

[Nightwatch]

Yes I do. I can't do smilies on my ipad. I may have mentioned that before.

Sorry if I got some inventive thoughts going.

 

Martyn

[Sir Nibble]

I did once rewind an A127 stator (my poor thumbs) make a permanent magnet rotor for it and drove it from the propshaft of a yacht and got 6-9A under sail. Atlantic crossing without running engine for charging!

[Machpoint005]

 

From what I can remember, the decibel (or actually the Bel) is a purely relative measure anyway, so a reading of 120 dB is meaningless without another reading to compare with. 'Absolute' sound levels are in dBm or something similar which AFAIK didn't exist when I were a lad.

 

Tim

 

I admit it -- I'm a consulting acoustical engineer. The dB is 10 times the log of a ratio, the ratio being the measured sound pressure over a reference sound pressure of 2 x 10^-5 Pa.

 

The article, as far as sound level measurements is concerned, is utter rubbish. Hence my sarky remark about the meter. Seriously though, if the author was using a Radio Shack sound level indicator, or worse still, a smartphone app, it would be little better than a random number generator. That's why real sound level meters cost several thousand squid and have to be calibrated at regular intervals.

 

I'd be surprised if a portable generator emitted more than about 80dB(A) at a metre, and most are considerably quieter.

 

 

Where 'noise measurements' are the context, the reference level is implicit.

Perhaps the person in question has the summertime blues ( yes I know its technically spring but its raining and cant think of anything else :-) )

 

Thats the first time since my schoodays in the sixties ive heard the word logarithmic. So, apparently they are important :-)

 

I use logarithms every day. Wonderful inventions.

 

No dBs do not work like that. Technically they are a "logarithmic" unit so although the actual pressure will double the dB level will not. A halving of distance gives an increase of 6dB..

So, if its 120dB at 15m then at 7.5m its 126, at 3.75m its 132 etc. This is still seriously loud.

 

...........Dave

 

Ok up to a point, but once you get close enough that the genny cannot be considered a 'point source' this relationship no longer holds true. No boat generator will emit as much as 120dB(A) at 15m.

[Robbo]

 

I'd be surprised if a portable generator emitted more than about 80dB(A) at a metre, and most are considerably quieter.

 

 

I've seen alot of generator's quoted at 72db at 7m. - These been the cheap n loud ones!

Edited April 25, 2014 by Robbo

[Machpoint005]

Cheap and loud are the operative words. I was thinking of a wee Honda or equivalent.

Also depends which side you stand on!

[Robbo]

Cheap and loud are the operative words. I was thinking of a wee Honda or equivalent.

Also depends which side you stand on!

 

A Google shows that a EU20i is 53-59dB(A) @ 7m

[Machpoint005]

 

I'd be surprised if a portable generator emitted more than about 80dB(A) at a metre, and most are considerably quieter.

 

 

 

 

A Google shows that a EU20i is 53-59dB(A) @ 7m

 

Well, I hesitate to say "I told you so", but there we are. A level of 59dB(A) at 7m will come out at around 73 - 74 dB(A) at a metre.

[Robbo]

 

 

 

Well, I hesitate to say "I told you so", but there we are. A level of 59dB(A) at 7m will come out at around 73 - 74 dB(A) at a metre.

But that's one of the quietest in the market, so guessing most would be above 80. Still not anywhere near120 thou!

 

 

Anyone got any specs for the kipor? That seems to be a popular boaters one.

Edited April 25, 2014 by Robbo

[Peter Thornton]

Always wondered what had happened to the de commissioned Concordes. Fair play to him for converting one into a power unit :-)

Actually..... I used to work for BAC when they were building the Concord and they DID market the engine as a stand alone generator!

[YamYam]

Actually..... I used to work for BAC when they were building the Concord and they DID market the engine as a stand alone generator!

:-). only been a member for just over a week and wanted for nothing so far. Amazing :-). There you go then, that wotsisname obviously heard a concorde engine, so now I'm inclined to believe him. NOT!!! :-) :-)

[Sir Nibble]

Actually..... I used to work for BAC when they were building the Concord and they DID market the engine as a stand alone generator!

Yup, the Olympus is also used for industrial power and of course to power warships. No reheat tho'! THAT would make a warship at full chat look DEAD cool even if it adds nothing to the speed.

[lexicon]

Found the suggestions in that article frankly jaw droppingly stupid.

So Mr ponting thinks that 30db will damage hearing according to health and safety.

I nearly spat out my coffee.

Someone better tell the British society of audiologists. The recommended level of noise at which a hearing test is valid is 35db(a) so how can that level be damaging to hearing?

I have nothing but contempt for such idiotic views.

[Leo No2]

For four Olympus 593 engines on reheat see -

 

it's at about 4:25 but in my view the whole video is worth watching. Put out by BA on the retirement of Concorde in October 2003.

Edited April 25, 2014 by Leo No2

[GUMPY]

I regularly used to fly out to Spain on an early evening flight we were always the next flight out after Concord I always got a seat on the correct side as watching it take off was one of the things that willstay with me for life.

Three other planes "do it for me"

Vulcan

Lightning

TSR2.

[YamYam]

I regularly used to fly out to Spain on an early evening flight we were always the next flight out after Concord I always got a seat on the correct side as watching it take off was one of the things that willstay with me for life.

Three other planes "do it for me"

Vulcan

Lightning

TSR2.

How could you leave out the Spitfire :-)

[GUMPY]

How could you leave out the Spitfire :-)

I'm not that old

All the above are planes from my youth

You could add Canbera, Bucaneer, Hunter and many more.

From a time when British aero engineering led the world before the politicos scrapped it.

[Mike Todd]

Gennys are annoying at ANY time.

Another thread has been discussing problems with charging batteries. It seems that the OP thought that running his engine for an hour a day would be enough for all of his needs. Yet another aspect to the failure to understand properly what living aboard a boat actually means. Even when cruising (occasionally or continuously) it is a constant concern to manage various utilities.

 

If a liveaboard as a full time day time job it is going to be all but impossible to comply with the regulations over running engines/generators I would have thouhgt.

[YamYam]

I'm not that old

All the above are planes from my youth

You could add Canbera, Bucaneer, Hunter and many more.

From a time when British aero engineering led the world before the politicos scrapped it.

Sorry, didn't mean to imply you were that old :-) Just a few Spitfires still flying today with the sweetest engine sound you've ever heard which will probably bring us back to decibel levels again and lovers of vintage engines I might add of which imone of those as well :-)

[GUMPY]

Sorry, didn't mean to imply you were that old :-) Just a few Spitfires still flying today with the sweetest engine sound you've ever heard which will probably bring us back to decibel levels again and lovers of vintage engines I might add of which imone of those as well :-)

Judging from your forum name I'm only 2years further on than you.

[YamYam]

Judging from your forum name I'm only 2years further on than you.

Well I'm just coming up to sixty but don't class myself as old. Yet anyway :-)

[George94]

I have been trying to find a statement in that NBW article which is true.

 

Clearly the 120dB claim is nonsense, but so too are the claims about HSE and permitted noise levels.

 

To the best of my knowledge, HSE is only concerned with dangerous noise at work, and says nothing about noise in the situation described. For that, you have to go to the Noise Act 1996 and the Noise & Statutory Nuisance Act 1993. Both of these are enforced in the main by the local authority, NOT the HSE.

 

The Secretary of State in 2008 ruled that noise levels emitted at night should not be more than 10 dB above the underlying noise level, with a permitted minimum of 34dB if the underlying noise level is less than 24dB. And that the measurement should be taken from within the neighbouring dwelling where the noise is being measured. Since the underlying noise level in a bedroom at night is around 30 dB, that means the measured level of the nuisance noise within the neighbouring dwelling should in most cases not exceed 40dB.

Edited April 26, 2014 by George94

[John Williamson 1955]

 

From what I can remember, the decibel (or actually the Bel) is a purely relative measure anyway, so a reading of 120 dB is meaningless without another reading to compare with. 'Absolute' sound levels are in dBm or something similar which AFAIK didn't exist when I were a lad.

 

Tim

When measuring sound levels in air there is an agreed sound pressure level which counts as 0dB. basically, it's the quietest sound that a person with normal hearing can hear. The maximum possible is limited by atmospheric pressure to 195 dB.

 

http://www.gcaudio.com/resources/howtos/loudness.html

 

When measuring signal levels in audio equipment, then again, there is a commonly agreed level marking 0dB, which is the voltage which will dissipate 1 milliwatt in a 600 ohm resistor or 0.775 volts.

 

A reading of 120db from a generator 70 feet away is likely the result of the operator reading the wrong scale on an analogue meter or a defective digital meter.

[George94]

When measuring sound levels in air there is an agreed sound pressure level which counts as 0dB. basically, it's the quietest sound that a person with normal hearing can hear. The maximum possible is limited by atmospheric pressure to 195 dB.

 

http://www.gcaudio.com/resources/howtos/loudness.html

 

When measuring signal levels in audio equipment, then again, there is a commonly agreed level marking 0dB, which is the voltage which will dissipate 1 milliwatt in a 600 ohm resistor or 0.775 volts.

 

A reading of 120db from a generator 70 feet away is likely the result of the operator reading the wrong scale on an analogue meter or a defective digital meter.

 

My money is on the first of those - a defective operator.