Engine noise

[karanight]

I’ve searched for the subject  ‘engine noise’ and was surprised to find no discussions on the subject, forgive me if I missed it 

Does anyone know a way to reduce the noise from the engine 

 

[Arthur Marshall]

Search for "soundproofing" - that should find it!

[Tony Brooks]

5 minutes ago, karanight said:

I’ve searched for the subject  ‘engine noise’ and was surprised to find no discussions on the subject, forgive me if I missed it 

Does anyone know a way to reduce the noise from the engine 

 

 

Let us assume you mean ordinary engine noise and not noise associated with wear and faulty/lose parts.

 

You can get acoustic blankets that you drape over the engine, keeping the air intake free, but I would avoid them in case it got caught in a moving part accidentally. you can also get slabs of sound attenuation material. typically about 3 to four inches thick foam with a very dense lead like layer in the middle. you can stick this to the underside of deck boards etc, or, as I did, make up an engine box and line the inside with this material. However, you must ensure adequate air flow into the box.

 

If it is a cruiser or semi-trad try gluing some closed cell neoprene foam strip to the underside of the deck boards where they sit on the supports. Again, ensure adequate intake air flow.

 

[Arthur Marshall]

Nothing makes a great deal of difference to an air cooled Lister. I've got insulation sheets under the deck planks and they do cut it down a bit but it certainly aint quiet. Noise cancelling earphones work, though !

[TheBiscuits]

7 minutes ago, Arthur Marshall said:

Nothing makes a great deal of difference to an air cooled Lister. I've got insulation sheets under the deck planks and they do cut it down a bit but it certainly aint quiet. Noise cancelling earphones work, though !

 

Half past two!

[Tracy D'arth]

Hydraulic drive with the engine in the bow, as far away from the steerer as possible.

[MrsM]

We've glued rubber sheeting to the underside of our deck boards and it makes a massive difference.

[Tony Brooks]

42 minutes ago, Arthur Marshall said:

Nothing makes a great deal of difference to an air cooled Lister. I've got insulation sheets under the deck planks and they do cut it down a bit but it certainly aint quiet. Noise cancelling earphones work, though !

 

That is hardly surprising with the added ventilation needed for the cooling air as well as combustion air. However, if the sound proofed case was fitted with proper labyrinth inlet and outlet air ducting, it would make a big difference. The trouble is I have yet to see that.

 

If the OP has any air cooled engine, then I agree trying to soundproof it is unlikely to be a good use of money or time.

[MtB]

1 hour ago, Tracy D'arth said:

Hydraulic drive with the engine in the bow, as far away from the steerer as possible.

 

Agreed. Design the boat properly in the first place.

 

My first two narrowboats were annoying to steer as no matter how much mucking about adding sound insulation you do, you will still be painfully aware of the large item of machinery running right under your feet. Put the engine somewhere else though, and a boat becomes blissfully quiet to the steerer. Either in a midships engine room (with bags of space around it for maintenance) or somewhere up forward where you just can't hear it from the steering position. 

 

 

 

 

 

Edited May 21, 2023 by MtB
Finesse a point.

[Hudds Lad]

Lots of sound deadening material and a hospital silencer, then people on the towpath will say "That's nice and quiet, is it electric?" and all you'll hear is something about a riot and epileptic. Nod and smile.

[Machpoint005]

There are engines...and noisy engines.

 

The thing to do before buyiny any of the so-called "soundproofing" materials is to make sure the deck boards for snugly and are sealed to their support runners.

 

As others have said, make sure there is enough airflow through the engine space, though: this depends on whether the hull designer thought of it.

 

Once the gaps have been eliminated, then look at adding materials. These work in two ways: 1. By adding to the mass of the deck boards; 2. By reducing the noise level in the engine space by absorption.

 

No.2 has very little effect.

 

In theory there might be thought to be a 3. By modifying the stiffness of the panels, but any such change will be the cube root of 4/5 of feck-all.

 

 

[Tonka]

2 hours ago, karanight said:

I’ve searched for the subject  ‘engine noise’ and was surprised to find no discussions on the subject, forgive me if I missed it 

Does anyone know a way to reduce the noise from the engine 

 

Turn it off

[Tony Brooks]

Also move the exhaust outlet from the side to the back, so sound does not bounce off the side of the canal back to the boat.

[karanight]

The engine is a water cooled  Canaline at the stern with the exhaust at the side

i was concerned about the engine overheating with foam type insulation 

[Tony Brooks]

29 minutes ago, karanight said:

The engine is a water cooled  Canaline at the stern with the exhaust at the side

i was concerned about the engine overheating with foam type insulation 

 It won't as long as your skin tank is an adequate size, typically 4 hp per sq ft, one side only. But you must make sure there is enough air intake space for combustion air AND alternator cooling. I would suggest a 3" x 3" hole just behind the alternator so the fan can draw cooler air through the alternator.

 

When I boxed JennyB's engine in for sound deadening, I only dropped the rear board on to the engine beds so there was plenty of space for air to be drawn into the box. Naturally, some sound did escape, but a lot did not.

[IanD]

You can also use acoustically-lined flexible ducting like this behind any ventilation holes to reduce noise to the outside world, a couple of feet long will do the job, a bend in it will also help...

 

https://www.ducting-express.co.uk/product/flexible-ducting/acoustic-flex/acoustic-aluminium-flexible-ducting-125mm-diameter-x-10-meters-long

 

Various sizes available, diamter quoted (125mm in this case) is internal, external is 50mm bigger.

 

Best sound insulation for panels/hatches is the type with a dense internal layer like this, it's 32mm thick:

 

https://www.asap-supplies.com/products/siderise-32mm-soundproofing-with-polymeric-barrier-silver-foil-x4-801434

Edited May 21, 2023 by IanD

[pete.i]

When I had my first narrowboat, a 30 footer trad stern with a BMC 1.5 engine called Keb, the original engine cover, which was a solid sheet of marine ply, had a lining of what looked to me like a horsehair layer then a layer of lead and then another layer of horsehair, a lead sandwich sort of affair. Anyway the the original engine cover had started to delaminate so I replaced it with a sheet of 18mm buffalo board. I didn't replace the sound deadening until much later but it was amazing how much difference that lead sandwich made. Downside was that it also made the deck board VERY heavy.

[IanD]

2 minutes ago, pete.i said:

When I had my first narrowboat, a 30 footer trad stern with a BMC 1.5 engine called Keb, the original engine cover, which was a solid sheet of marine ply, had a lining of what looked to me like a horsehair layer then a layer of lead and then another layer of horsehair, a lead sandwich sort of affair. Anyway the the original engine cover had started to delaminate so I replaced it with a sheet of 18mm buffalo board. I didn't replace the sound deadening until much later but it was amazing how much difference that lead sandwich made. Downside was that it also made the deck board VERY heavy.

Insulation with a lead layer has largely been replaced by a dense polymeric layer like the one I linked to, which is cheaper but is claimed to be just as effective. See lead one below...

 

https://www.asap-supplies.com/products/siderise-32mm-soundproofing-with-lead-barrier-silver-foil-x4-801484

[PeterF]

Recognising you from previous posts, yours is a new Collingwood sail away so I do not expect that you have anything in terms of sound proofing and have a cheap minimum cost small silencer on the exhaust (do check you actually have one).

 

On our current boat we have some of the acoustic foam lining with polymeric layer that IanD linked to above under the deck boards. We also put a strip of self adhesive neoprene around the edge of the deck boards where they sit on the support channels to remove any air gaps that sound can escape through. The largest contribution however is having specified a hospital silencer before the build commenced. When on tick over we often get asked if we are electric (No). You may like to consider one if there is room to retrofit one.

 

https://www.midlandchandlers.co.uk/products/ag-hospital-silencer-12-x-32-with-1-1-2-bsp-male-ports-ea-008

 

A previous boat with a cruiser stern had the engine bay air intakes in the rear cabin bulkhead facing backwards directed towards the steering position, a box mounted over these with the opening pointed away from the steering position and lined with acoustic foam reduced the noise escaping from these.

[Tony Brooks]

5 minutes ago, PeterF said:

You may like to consider one if there is room to retrofit one.

 

I got a "near hospital silencer" from T W Marine @ High Peak. It is smaller than a hospital silencer but nearly as good. I got it mounted parallel with the engine to one side, with the outlet at the stern. As others have said, we have been asked if we were electric.

Edited May 21, 2023 by Tony Brooks

[karanight]

21 minutes ago, PeterF said:

The largest contribution however is having specified a hospital silencer before the build commenced

I’d heard of a hospital silencer and asked how much it would cost to have one fitted. I got a price of £5000 and I couldn’t afford that so I didn’t go for one. I’m shocked how cheap they are.  I’ll look into having one retrofitted 

[OldGoat]

When we hired boats many decades ago, I learned from Teddesley (under the tutilage of Peter Milward (much missed) that the easiest way for quiet boating was a watercooled exhaust. When we built our-very-much-missed boat, I ordered a watercooled exhaust manifold and freshwater pump as part of the beta marine setup for our first and only boat. 

Some 30 years later I doubt whether the new / next owner apreciates the quetmess of the boat that she has bought....

[Tony Brooks]

1 minute ago, OldGoat said:

When we hired boats many decades ago, I learned from Teddesley (under the tutilage of Peter Milward (much missed) that the easiest way for quiet boating was a watercooled exhaust. When we built our-very-much-missed boat, I ordered a watercooled exhaust manifold and freshwater pump as part of the beta marine setup for our first and only boat. 

Some 30 years later I doubt whether the new / next owner apreciates the quetmess of the boat that she has bought....

 

Or the added propensity for extra complexity, maintenance and failure, possibly at very inconvenient times, that such systems imply. I agree, the quietest common system, but it won't be when the raw water fails and burns a hole through the exhaust hose or silencer. Fine if you go into it with our eyes open, but I would never suggest a new canal boater should opt for such systems.

[MtB]

6 hours ago, Hudds Lad said:

Lots of sound deadening material and a hospital silencer, then people on the towpath will say "That's nice and quiet, is it electric?" and all you'll hear is something about a riot and epileptic. Nod and smile.

 

 

This raises another point. 

 

Is the OP's concern to make the boat quieter for people around the boat i.e. towpath users? If so, concentrate on exhaust noise and the silencer to get a 'quiet boat people mistake for electric'. 

 

If it is to reduce the noise levels suffered by the steerer, this won't make much difference and best to concentrate on making deck boards fit accurately and adding mass (e.g. the lead sheeting mentioned earlier) and wadding to reduce sound penetration through the boards. 

[Alan de Enfield]

21 minutes ago, karanight said:

I’d heard of a hospital silencer and asked how much it would cost to have one fitted. I got a price of £5000 and I couldn’t afford that so I didn’t go for one. I’m shocked how cheap they are.  I’ll look into having one retrofitted 

 

That's the polite way of saying, "not interested, go away".