Csail
N/A
Why are boat engines so noisy? Mine is quite new but is well noisy compared to the Audi 2.5 car engine.
Engine noise
- Thread starter Csail
- Start date
Divemaster1
Well-Known Member
1) number of cylinders
2) age of construction (not age, but design)... bet your boat engine,if at same volume as car engine, is heavier and run at lower RPM
3) Your boat engine is most of the time running at (heavy for car engine) load (as if you were constantly accellerating)
4) Installed in a sound box (fibreglass) which amplifies the sound
5) Long stroke rather than short stroke
.... and loads more....
2) age of construction (not age, but design)... bet your boat engine,if at same volume as car engine, is heavier and run at lower RPM
3) Your boat engine is most of the time running at (heavy for car engine) load (as if you were constantly accellerating)
4) Installed in a sound box (fibreglass) which amplifies the sound
5) Long stroke rather than short stroke
.... and loads more....
omega2
Well-Known Member
No silencer
jimmcgee
Well-Known Member
and the design is about 20 years behind a car engine.
Warpa
Well-Known Member
Elessar
Well-Known Member
because people tend not to test drive boats and certainly dont compare them back to back, so the manufacturers spend the money on fitting boat show bling.
some brand new mobos would be illegal to use without ear defenders if they were a place of work.
easily improved, far easier to do in build though.
Latestarter1
Well-Known Member
I would tend to agree. Potential owners do seem to be seduced by bling rather than substance.
OP's question is a bit scattergun and non specific, add to this the fact that trying to design a quiet diesel engine is akin to attempting to design a quiet hand grenade.
However marine diesel engines have become dramatically quieter with the advent of electronic control, common rail enables you to play many tunes with the timing table to reduce diesel knock, for example common rail can take as much as 10 dBA sound pressure at rated speed out of an engine platform which previously had an in line fuel injection pump. Decent manufacturers often list sound pressure on data sheets.
Also remember the VW/Audi V6 uses a timing belt, heavier duty engines found in marine applications use helical or straight cut gears to drive their cams, grumbling gears are very robust but are a big noise generator.
With care you can engineer out a significant amout of noise and vibration from a marine installation, however it does cost money, and appears to come way down the list after bling.
Spi D
...
If you compare apples to apples...
A boat engine that is found also in genset, tractor, bus, truck or other use will sound about the same. Listen to a Bobcat or something, they aren't quiet either.
In cars a huge effort goes into silencing - as a matter of fact they are built to incorporate sound barriers, vibration stoppers etc.
No so in a boat. The engines sits right on the spine, sometimes on rubbers and in rare designs in insulated compartmens. Noise insulation is the main concern and, luckily, often can be fitted afterwards.
I'd suggest you go for items with a documented effect. If you like, you may also find carpets with sounddeadening properties (layer of lead, I suppose).
A boat engine that is found also in genset, tractor, bus, truck or other use will sound about the same. Listen to a Bobcat or something, they aren't quiet either.
In cars a huge effort goes into silencing - as a matter of fact they are built to incorporate sound barriers, vibration stoppers etc.
No so in a boat. The engines sits right on the spine, sometimes on rubbers and in rare designs in insulated compartmens. Noise insulation is the main concern and, luckily, often can be fitted afterwards.
I'd suggest you go for items with a documented effect. If you like, you may also find carpets with sounddeadening properties (layer of lead, I suppose).
Last edited:
Elessar
Well-Known Member
If you compare apples to apples...
A boat engine that is found also in genset, tractor, bus, truck or other use will sound about the same. Listen to a Bobcat or something, they aren't quiet either.
In cars a huge effort goes into silencing - as a matter of fact they are built to incorporate sound barriers, vibration stoppers etc.
No so in a boat. The engines sits right on the spine, sometimes on rubbers and in rare designs in insulated compartmens. Noise insulation is the main concern and, luckily, often can be fitted afterwards.
I'd suggest you go for items with a documented effect. If you like, you may also find carpets with sounddeadening properties (layer of lead, I suppose).
Errr - TV and film industry genset often use volvo penta engines. And they are silent enough to use right next to the action.
It is possible to make boats quiet, despite the base engines.
Spi D
...
Get your point.
Thing is that the same naked engine, before encapsulation etc., will make the same noise regardless of use.
And to stay with the initial subject, the difference experienced between uses is down to the sound insulation surrounding it. Built in, added or retrofitted.
Volvo states that their late technology IPS 600 diesel emits 95 dbA at 1000 rpm and 113 dbA at 3500 rpm.
http://www.volvopentastore.net/files/t_ips600.pdf
Common levels for comparison
• 40 quiet residential area
• 70 freeway traffic
• 85 noisy restaurant
• 90 truck
• 90 shouted conversation
• 95-110 motorcycle
Source: http://www.lowermanhattan.info/extras/pdf/062007_SpecificNoiseLevelsforCommonNoises.pdf
Only shows that sound insulation is important and, when done properly makes a huge difference. It goes without saying an engine which by design makes less noise needs less insulation (like Volvo D4, Yanmar (BMW) 3 litre and more) to reach a comfortable level.
Thing is that the same naked engine, before encapsulation etc., will make the same noise regardless of use.
And to stay with the initial subject, the difference experienced between uses is down to the sound insulation surrounding it. Built in, added or retrofitted.
Volvo states that their late technology IPS 600 diesel emits 95 dbA at 1000 rpm and 113 dbA at 3500 rpm.
http://www.volvopentastore.net/files/t_ips600.pdf
Common levels for comparison
• 40 quiet residential area
• 70 freeway traffic
• 85 noisy restaurant
• 90 truck
• 90 shouted conversation
• 95-110 motorcycle
Source: http://www.lowermanhattan.info/extras/pdf/062007_SpecificNoiseLevelsforCommonNoises.pdf
Only shows that sound insulation is important and, when done properly makes a huge difference. It goes without saying an engine which by design makes less noise needs less insulation (like Volvo D4, Yanmar (BMW) 3 litre and more) to reach a comfortable level.
Elessar
Well-Known Member
david_bagshaw
Well-Known Member
If you have ever run the engine(s) while chocked up ashore, that is another big suprise how the hull in water amplifies all noise.
Assassin
Well-Known Member
There are solutions to reduce noise, many manufacturers produce kits for noise reduction, mainly for the automotive industry admittedly, but many will take on other challenges such as boats.
It may be worthwhile contacting a few of these and see what, if anything, they will be willing to do for you.
It may be worthwhile contacting a few of these and see what, if anything, they will be willing to do for you.
pappaecho
Well-Known Member
The car makers are pretty good at stopping resonance, and boat makers are not.
My S Type Jag has a 2.7 diesel which is very quiet, so much so that most passengers do not know it is an oil burner.
Two weeks ago my sump protector suffered from "clip problems" and was taken off to protect it whilst new clips were sourced.
The difference in engine noise is incredible, and clearly has got something to do with resonance, which apparently is a black art
My S Type Jag has a 2.7 diesel which is very quiet, so much so that most passengers do not know it is an oil burner.
Two weeks ago my sump protector suffered from "clip problems" and was taken off to protect it whilst new clips were sourced.
The difference in engine noise is incredible, and clearly has got something to do with resonance, which apparently is a black art
