sound levels in salon

[vas]

Hello again,

boat will be moved out tomorrow so my last chances to check things.

Genny felt a bit too noisy to me, so downloaded soundmeter on my android mobile, setup the profile for my phone and did some tests.
Boat in the marina, not exceptionally tranquil as it's 30 or so metres from a street that is not too busy, but there are cars passing regularly (as in one very 5-10secs)

Anyway, phone on the helm on a solid surface vinyl lined so softish no reverb. Closed the salon door and did the following tests:

Engines off : 38-40db
both engines on idle: 80db
engoff genny on : 70db

Genny is aft of the stbrd engine so under the salon floor.
Genny is an oldish MASE green something like 4-5kva, proper marine thing, with all the pipework in place a silencer (me thinks) and gasses/water exit at the stbrd engine exhaust grp tunnel at the transom.

Called my mate with the P410 5 boats down the pontoon (his is a very quiet genny), heard it and freaked out. Suggested I move the genny aft in the lazerrete (sp?) and scrap my one water tank taking the place there (or move it fwd a bit) Also recommends to do a decent isolation box for it once in place.

Don't mind the shifting things about too much, I honestly think that if the genny stays where it is, will be only used for the espressos and the watermaker (unless I get a 24V one...) I doubt anyone will agree to use it for the aircon either...

Any views?

cheers

V.

 

[Nick_H]

Putting a noisy genny in the laz is only going to make it more intrusive in the cockpit, so i'm not sure you gain anything. My genny is under the saloon floor, and its barely noticeable most of the time, so I think you may be better to focus on sound insulation. From your description it sounds like there's no acoustic cabinet? If so, then i'd start by having one fabricated, or buy an OE one from the manufacturer if available. That's likely to cost a fair bit, so as an alternative you may be able to drape acoustic mats over it and secure the corners, but i don't know how effective that would be. It seems strange it would have an exhaust silencer but no cabinet, or did I misunderstand that?

I assume its on anti vibration mountings? If not, then that may be worth considering as well.

 

[vas]

Putting a noisy genny in the laz is only going to make it more intrusive in the cockpit, so i'm not sure you gain anything. My genny is under the saloon floor, and its barely noticeable most of the time, so I think you may be better to focus on sound insulation. From your description it sounds like there's no acoustic cabinet? If so, then i'd start by having one fabricated, or buy an OE one from the manufacturer if available. That's likely to cost a fair bit, so as an alternative you may be able to drape acoustic mats over it and secure the corners, but i don't know how effective that would be. It seems strange it would have an exhaust silencer but no cabinet, or did I misunderstand that?

I assume its on anti vibration mountings? If not, then that may be worth considering as well.

Nick,

sorry I wasn't clear enough, there is an acoustic cabinet but v.shabby and with broken hinges. In effect it's kept in place with elastic bands, the individual parts are not matching properly and sealing nicely one to another. The 20mm thick insulation is mostly intact on this grp cabinet.
It seems that the elastic mounts are ok, but maybe buggered and transmit all vibration to the timber frame.
I'd rather improve the cabinet and even built another one around it with extra insulation rather than embarking in this shifting about project tbh as there's a massive list of things to do already.

You don't happen to have any measurements of sound levels in the salon or inner helm do you?

cheers

V.

 

[BartW]

Nick,

sorry I wasn't clear enough, there is an acoustic cabinet but v.shabby and with broken hinges. In effect it's kept in place with elastic bands, the individual parts are not matching properly and sealing nicely one to another. The 20mm thick insulation is mostly intact on this grp cabinet.
It seems that the elastic mounts are ok, but maybe buggered and transmit all vibration to the timber frame.
I'd rather improve the cabinet and even built another one around it with extra insulation rather than embarking in this shifting about project tbh as there's a massive list of things to do already.

You don't happen to have any measurements of sound levels in the salon or inner helm do you?

cheers

V.

if the genny has a sound isolating box, then you're good, because then you can improve that, will tell you how,
(my business has just buyld a extremely good isolated Radio OB -Van)
if the genny didn't have isolation, you could face cooling problems after putting a cabinet around it.

but I wouldn't worry about the genny at this moment, as in my experience,
we have used the genny very little our first season, (even while it is extremely silent)
- the airco almost not used it. On anker we could do without it, and in the harbour you have shore power.
but I'm aware that in Greece it might be hotter then SOF
- watermaker, almost not used it, unless you stay long periods on anker.

we used the genny only for the dishwasher, waterboiler and washing machine,
if you have none of these, and put a decent invertor, you could do mostly without the genny.

In my small boat (28ft) I have a 12/230V 3Kw Victron battery charger / invertor.

In the other boat I have the 24V version.
and that one is used permanently for: loading cell phones, laptops, Walky Talky's, portable VHF, and for looking TV (yes a few silly guests did this )


about sound insulation, for a start;

- make sure the case is closed perfectly, and all panels are tight togetehr, no gaps. repair if necessary with solid material, not foam nor tissue nor tape...
- The foam inside does not help a lot, but needs to be there,
- then try to find out where most of the sound comes from,
- when too much noice comes through the case, you can improve that by glue-ing a layer of rubber (heavy flexible material) on all panels, on the outside.
you could do the same with the ceiling of the engine room,

but it is also possible that the sound comes through windows, doors, ventilation openings, ....
or contact vibration through the structure, tubes, ...

for sound isolation you need to add weight,(rubber mats fe) and this is usually not wanted in a boat....

 

[Nick_H]

No, I don't have any dB figures, but we're forever forgetting to turn it off because after the initial switch on we don't notice it.

I'd start by repairing the cabinet, and maybe replace the 20mm foam with a premium sound deadening material, and thicker if there's room. Also make sure the sound panelling on the engine room is complete, and maybe fit a door seal on the engine room hatch.

If that doesn't do the business then you could have an acoustic blanket made that fits over the cabinet with velcro straps. I think someone on here makes them.

 

[Deleted User YDKXO]

Actually 70dB is not that high in general terms. I suspect it is the quality of the sound that is disturbing you, not the sound level itself. I'm guessing that your genny has one of those nasty high revving single cylinder engines which are excellent at generating noise and vibration. IMHO, I would just buy a new sound enclosure from Mase and make sure it is well fitted because noise is very good at escaping through the smallest gaps. Also check that the engine mountings are in good order. Personally, I would be wary of indiscriminately wrapping some kind of soundproofing material around the genny because it's a potential fire hazard. Also check that the hatches to the engine bay in your saloon fit well and there are no gaps. Lastly I dont know whether you have carpet in your saloon but carpet is a good sound deadening material.
Having had experience of single cylinder engine gennies on a number of boats, there is a limit to how much you can achieve and the genny will never be what you might call quiet

 

[vas]

but I wouldn't worry about the genny at this moment, as in my experience,
we have used the genny very little our first season, (even while it is extremely silent)
- the airco almost not used it. On anker we could do without it, and in the harbour you have shore power.
but I'm aware that in Greece it might be hotter then SOF
- watermaker, almost not used it, unless you stay long periods on anker.

we used the genny only for the dishwasher, waterboiler and washing machine, if you have none of these, and put a decent invertor, you could do mostly without the genny.

true, I'm thinking that the gen will be mainly for aircon before noon siesta and some late afternoons and coffee machine. Wife cannot live without coffee, I'm having problems with heat, so gen is on

In my small boat (28ft) I have a 12/230V 3Kw Victron battery charger / invertor.

In the other boat I have the 24V version.
and that one is used permanently for: loading cell phones, laptops, Walky Talky's, portable VHF, and for looking TV (yes a few silly guests did this )

I also have a small inverter for laptop and cellphones but I need to sort my electrics and figure out how I'm going to be running most things without the gen. I agree it wont be very difficult.

about sound insulation, for a start;

- make sure the case is closed perfectly, and all panels are tight togetehr, no gaps. repair if necessary with solid material, not foam nor tissue nor tape...
- The foam inside does not help a lot, but needs to be there,
- then try to find out where most of the sound comes from,
- when too much noice comes through the case, you can improve that by glue-ing a layer of rubber (heavy flexible material) on all panels, on the outside.
you could do the same with the ceiling of the engine room,

but it is also possible that the sound comes through windows, doors, ventilation openings, ....
or contact vibration through the structure, tubes, ...

for sound isolation you need to add weight,(rubber mats fe) and this is usually not wanted in a boat....

Will try to clean the mess down there, see how the factory soundbox fits together and try to repair it.

Then I'll come back to you Bart on suggestions about the heavy flexible rubber you recommend. I'm familiar with Ricofon for sound deadening but I understand that's different.

cheers

V

 

[vas]

Actually 70dB is not that high in general terms. I suspect it is the quality of the sound that is disturbing you, not the sound level itself. I'm guessing that your genny has one of those nasty high revving single cylinder engines which are excellent at generating noise and vibration. IMHO, I would just buy a new sound enclosure from Mase and make sure it is well fitted because noise is very good at escaping through the smallest gaps. Also check that the engine mountings are in good order. Personally, I would be wary of indiscriminately wrapping some kind of soundproofing material around the genny because it's a potential fire hazard. Also check that the hatches to the engine bay in your saloon fit well and there are no gaps. Lastly I dont know whether you have carpet in your saloon but carpet is a good sound deadening material.
Having had experience of single cylinder engine gennies on a number of boats, there is a limit to how much you can achieve and the genny will never be what you might call quiet

I think you are spot on, it's a single cylinder job running at 3K+ rpm compared to a 3cyl <2K rpm my friend has on his Princess. This whinning is awful if you're trying to relax, don't know who thought of that but wasn't at all clever...
Wondering how this gens get their fresh air though, unless they have complex soundtraps that's going to be the first suspect for noise escapes...

I have a sh!tty carpet right now, will replace with a softrubberish lining and a thicker carpet and I hope that's going to be of great help. Luckily even without carpets at the cabins noise is less, once everything is fitted it should be much better there.

cheers

V.

 

[BartW]

... and coffee machine. Wife cannot live without coffee.

Elly doesn't drink coffe, but I am adicted.
when we got Blue angel, there were 2 Bialetti's in the galley
now I alway's use these on the boat and the coffe is delicious
this is part of the Blue Angel atmosphere

 

[Deleted User YDKXO]

I think you are spot on, it's a single cylinder job running at 3K+ rpm compared to a 3cyl <2K rpm my friend has on his Princess. This whinning is awful if you're trying to relax, don't know who thought of that but wasn't at all clever...
Wondering how this gens get their fresh air though, unless they have complex soundtraps that's going to be the first suspect for noise escapes...

Yup, ironically bigger gennies running 3 or 4 cylinder engines at 1500rpm are noticeably quieter and less vibey.

 

[Hurricane]

Actually 70dB is not that high in general terms. I suspect it is the quality of the sound that is disturbing you, not the sound level itself. I'm guessing that your genny has one of those nasty high revving single cylinder engines which are excellent at generating noise and vibration. IMHO, I would just buy a new sound enclosure from Mase and make sure it is well fitted because noise is very good at escaping through the smallest gaps. Also check that the engine mountings are in good order. Personally, I would be wary of indiscriminately wrapping some kind of soundproofing material around the genny because it's a potential fire hazard. Also check that the hatches to the engine bay in your saloon fit well and there are no gaps. Lastly I dont know whether you have carpet in your saloon but carpet is a good sound deadening material.
Having had experience of single cylinder engine gennies on a number of boats, there is a limit to how much you can achieve and the genny will never be what you might call quiet

From my days at college - many years ago, you cant just specify a level of 70db.
70 db - at what frequency?

I know the OP only has an Android app to measure and, in his position I'd try the same but a full analysis would look at the sound power levels across a range of frequencies.
A simple way of measuring is to apply a weighting to the reading.
From memory, sound measuring meters use a dba weighting which, I believe, is supposed to be a weighting that matches human hearing.

Anyway, simply saying that it is 70db isnt necessarily saying anything.

Also remember that db is not a linear scale - you cant just add sound power levels together.

Without proper test equipment, I think I would just repair/experiment with the existing sound insulation.

 

[BartW]

From my days at college - many years ago, you cant just specify a level of 70db.
70 db - at what frequency?

I know the OP only has an Android app to measure and, in his position I'd try the same but a full analysis would look at the sound power levels across a range of frequencies.
A simple way of measuring is to apply a weighting to the reading.
From memory, sound measuring meters use a dba weighting which, I believe, is supposed to be a weighting that matches human hearing.

Anyway, simply saying that it is 70db isnt necessarily saying anything.

Also remember that db is not a linear scale - you cant just add sound power levels together.

Without proper test equipment, I think I would just repair/experiment with the existing sound insulation.

You have good memory Mike, or you are still that young

dB sound level measurements are usually full audio band.
The dB weighing filter A,B or C mainly difference is in the low frequency range and this is of less influence for the genny measurement,
the dB sound level measurement (usually dBA) gives a good indication of the sound level, but the problem is that the mike in this android celphone is most certainly not calibrated,
and the frequency response of the microphone is only speach freq range,
so the measurement hasn't got any reference, not at all accurate

Without proper test equipment, I think I would just repair/experiment with the existing sound insulation.

agree

 

[vas]

I fully agree with you experts, the only reason I mentioned db from my mobile is to have a vague reference to some sort of sound level. It's obvious the free applet is not calibrated, we do have decent machinery at the dept but I don't want to drag a technician + equipment to the boat just for testing (although it's a 400m walk and I should do that next year).

Yes it is higher pitch as Deleted User points, and yes it's annoying, looks like I'll take the suggestion and try to improve on what I have and do better job at insulating under the salon floor and over it (under the carpet) We'll see in the summer how the experiment goes.

on a less serious note, Bart home espresso machine played up yesterday, so the video you posted was perfectly timed to remind me to unhide a 12yo wedding present, unused in a cupboard: an beautiful Aldo Rossi La Cupola Alessi espresso machine. Cleaned it and made for wife and myself a nice espresso in the morning. Rather too strong, hence even after lots of alcohol in the evening I still don't feel like going to bed...

Thing is if I do insulated slightly better the fly floor and front cabin roof, I may not need an air-con (and in effect the genny) at all... We shall see.

cheers

V

 

[BartW]

on a less serious note, Bart home espresso machine played up yesterday, so the video you posted was perfectly timed to remind me to unhide a 12yo wedding present, unused in a cupboard: an beautiful Aldo Rossi La Cupola Alessi espresso machine. Cleaned it and made for wife and myself a nice espresso in the morning. Rather too strong, hence even after lots of alcohol in the evening I still don't feel like going to bed...

enjoy life