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How noisy inside boat when engine running?


Pirateringo

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3 minutes ago, Pirateringo said:

When my engines running the inside of my boat is very noisy. Is this normal? I always thought it would be quieter 

Depends on...

  • The engine make. 
  • Whether the engine is air cooled or water cooled. 
  • The engine location. 
  • The engine’s mounting method. 
  • The soundproofing around the engine. 
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An Isuzu should be pretty quiet compared with say a Lister. Looks like you need some sound proofing. 

Just now, Tony Brooks said:

How the shaft is isolated from engaging movement/vibration. How much stuff like widows and cupboard contents are rattling and so on.

Yup, that too :)

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Made a big difference to the sound of the engine under way inside the boat when I fitted a Python Drive.  Also, sitting up the front of the boat I can barely hear it when it it running at around 1000 rpm out of gear.

 Engine is 42 HP  Vetus with standard exhaust and no sound insulation except under the deck boards.

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40 minutes ago, Machpoint005 said:

 

No, in the sense of adding absorptive materials. Yes, in the sense of investigating the mechanism(s) of sound transmission.

I suggest the exhaust system as a first port of call.

Until the OP can give us an idea about what the noise is then I would suggest trying to  stop sympathetic vibrations from things like doors, windows, crocker & cutlery. Also loose parts of the fit-out. What cause that vibration is, as above, open to question. I think exhaust noise makes itself apparent far more outside the boat than in.

 

Its a four cylinder and one that is usually flexibly mounted so if the noise is worse in gear than neutral I would suggest shaft alignment unless they have an Aquadrive/Pythondrive type coupling.

.

 

Edited by Tony Brooks
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I was surprised how noisy our (ex-hire) boat was with an Isuzu 42 when we got it. Flexibly mounted with Aquadrive. At cruising speed difficulty to hold normal conversation on back deck, and very noisy inside. 

 

One of the first jobs was sound insulation (foil faced foam sandwich type with lead like layer in the middle), followed by hospital silencer. Whilst it's not silent by any means, you can easily hold normal conversation on back deck at cruising speeds without raising voices, and when idling can't hear it at all at front of boat (inside our out). There's been times I've accused the wife of turning it off, only to find it still running when I venture back there! Really surprised how much difference it made, and surprised all boats don't have this. 

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It doesn't seem as loud on the deck as it does inside. It's like a deep rumbling and the vibration is quite noticeable. Thanks for all the replies 

3 hours ago, Alan de Enfield said:

It could of course be the OP's 1st boat and he has only recently purchased it, with expectations of noise levels being similar to 'being sat in a car

LOL this made me laugh. It is my first boat. But I've been on a few trips on boats and never really noticed the vibration and sound like this. 

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21 minutes ago, Pirateringo said:

It doesn't seem as loud on the deck as it does inside. It's like a deep rumbling and the vibration is quite noticeable. Thanks for all the replies 

LOL this made me laugh. It is my first boat. But I've been on a few trips on boats and never really noticed the vibration and sound like this. 

If Vibration is a problem did you have the engine mounts looked at for the survey ?

 

It is not uncommon for one or more of the engine mount rubbers to 'delaminate' or become detached from the metal, even for one to fail completely.

 

WITH THE UTMOST CARE.

 

With the engine running - Take a vey long screwdriver (or mooring pin) and put one end in / tightly up to your ear.

Take the other end and 'dab' it onto the engine mounts and all over the engine.

 

The engine could be out of balance if one cylinder is not firing

 

WATCH OUT AND STAY CLEAR OF ROTATING PARTS

 

You will feel the source of the vibration in your ear bones as soon as you get close to it.

 

 

Edited by Alan de Enfield
  • Greenie 1
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25 minutes ago, Alan de Enfield said:

You will feel the source of the vibration in your ear bones as soon as you get close to it.

And, if I remember my medical training correctly, your ear bone is connected to your brain bone - is that how it works?

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If the mounts are loose, worn or otherwise broken that would allow the shaft to bang about in the stern gear. Even it they are not that sounds horribly like shaft noise to me unless it does it just as markedly in neutral.

 

Edited to add:-

 

still need to know if its the same in and out of gear because a low rumble in gear could be a gearbox bearing.

Edited by Tony Brooks
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7 hours ago, Pirateringo said:

When my engines running the inside of my boat is very noisy. Is this normal? I always thought it would be quieter 

 

I’m usually steering so unaware of the noise inside. 

 

On the odd occasion when I’m inside and someone else is steering I’m surprised how noisy it is. 

 

 if I trust the steerer I can sleep through the noise

 

 

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14 minutes ago, The Dreamer said:

Same engine in our 69 footer.  In the rear cabin, you can hear it, but I wouldn’t say it’s noisy.  Down front, you can’t hear it at all...

Hmm it was from the front I experienced the noise. I'm guessing there's something up. 

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57 minutes ago, Tony Brooks said:

If the mounts are loose, worn or otherwise broken that would allow the shaft to bang about in the stern gear. Even it they are not that sounds horribly like shaft noise to me unless it does it just as markedly in neutral.

 

Edited to add:-

 

still need to know if its the same in and out of gear because a low rumble in gear could be a gearbox bearing.

Hi Tony will find out when I'm back at boat ?

Just now, Goliath said:

It’s what it sounds like from the outside anyway. 

 

?

Its not too loud outside in my opinion, certainly no louder than others I've heard 

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8 hours ago, WotEver said:

Depends on...

  • The engine make. 
  • Whether the engine is air cooled or water cooled. 
  • The engine location. 
  • The engine’s mounting method. 
  • The soundproofing around the engine. 

You forgot 'how good is your hearing'

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