TW Marine Hospital Silencers

[Noah]

I need a new exhaust silencer for my Beta Kubota and I'm thinking of buying a "compact" hospital type from TW Marine. Has anybody fitted one, and how effective was it? I expect that they will not give the noise attenuation of the full-size version but that's maybe not a bad thing as I don't want to hear all the other noises that my engine, drive and prop makes. I have already fitted some effective sound insulation and all I now hear is an irritating Jap four cylinder exhaust note!

 

Noah

[charles123]

I need a new exhaust silencer for my Beta Kubota and I'm thinking of buying a "compact" hospital type from TW Marine. Has anybody fitted one, and how effective was it? I expect that they will not give the noise attenuation of the full-size version but that's maybe not a bad thing as I don't want to hear all the other noises that my engine, drive and prop makes. I have already fitted some effective sound insulation and all I now hear is an irritating Jap four cylinder exhaust note!

 

Noah

 

 

I dont have personal experience but since you have a need to replace your silence it makes sense to upgrade and pay a little more. The exhaust noise is just one area of the overall noise level but since you have addressed others such as sound insulation a better silence can only help. When I get the need for a new silencer I will do as you propose

 

Charles

[stuart]

As a slightly off topic question, how long do exhausts usually last on a narrow boat before they need replacing?

Edited July 4, 2006 by stuart

[DaveR]

still on the original one on my Kubota . . . . 2,200 hours now and still sound.

 

Carry a repair kit though

[Keeping Up]

As a slightly off topic question, how long do exhausts usually last on a narrow boat before they need replacing?

We replaced ours last year, after 13 years (about 5000 hours of cruising). It was very rusty inside, in danger of falling apart, although it still worked well as a silencer,

[Noah]

still on the original one on my Kubota . . . . 2,200 hours now and still sound.

2,300 hrs (and 14years) on mine and it's just starting to break up! Little sign of deterioration on the outside of the silencer but the baffles have started to fall apart. I first became aware when sparks flew from the outlet on a night cruise. It's now a lot louder than before. I actually like to hear the sound of a slow revving traditional engine whether it's on a boat, car or bike but modern engines just don't sound pleasing to my ear and I'd rather listen to birdsong and stuff!

 

Today I phoned BetaMarine (the Kubota's mariniser) to ask if there would be a problem with back-pressure from a well-muffled hospital silencer and was advised that thre would be no problem as long as the total exhaust run was not of excessive length.

 

Noah

[hnb2907]

I need a new exhaust silencer for my Beta Kubota and I'm thinking of buying a "compact" hospital type from TW Marine. Has anybody fitted one, and how effective was it? I expect that they will not give the noise attenuation of the full-size version but that's maybe not a bad thing as I don't want to hear all the other noises that my engine, drive and prop makes. I have already fitted some effective sound insulation and all I now hear is an irritating Jap four cylinder exhaust note!

 

Noah

 

Hey,

 

That was some of the best money I ever spent on "Esther". Had a 2 week holiday from work and went up to TW Marine to pick the largest silencer I could fit in the engine bay. They're a great bunch of folks and very helpful - usually have a quick chat with them at the shows too.

 

Back to the silencer. The engine is a Shire 800, 3 cylinder job, which was originally installed on its bog standard exhaust. By putting the hospital silencer in, reduced the noise by 12-15dB on the deck, which may not sound a lot, but it certainly is. I then found that the noise of the engine air filter intake and gearbox could be heard, as the original booming noise from the silencer was covering it up! It meant that you could then have a conversation and hear each other, and the exhaust noise wasn't booming around in tunnels etc.

 

I seem to remember that you need to find a hospital silencer that's big enough but not too big - the TW marine folks will help you out with that if you call in/'phone.

 

Take a look at www.hnb2907.co.uk/esther I've uploaded some pictures, unfortunately I can't find any of Esther post-install but there are some...! Looking at the 2nd photo, the new silencer is sat on the counter, parallel to the engine/side of the hull, with the inlet (front) fitting pointing towards the camera, and on the right hand side, roughly under where the original silencer was.

The piping is a little convoluted, it's got a water trap between the silencer and the skin fitting, but it certainly hasn't caused any problems.

 

There's also some pictures of Horus, before and after the silencer upgrade. It's not quite as successful because I think the outlet pipe isn't long enough. I'd like to move it so that there's about 2 to 3 foot of piping either side of the silencer, which will change the harmonics of the total length of the exhaust system.

 

 

You will notice that there 'appears' to be a little more engine smoke - general thoughts is that it makes your engine smoke more - I actually think it's because the velocity of the gases leaving the exhaust is a lot less ( and I won't go into the techy stuff). So, instead of the smoke being sent up the towpath at '90mph' on each cylinder exhaust, it seems to steady amble out at a constant rate, so you see it. The difference in how the gases escape is part of the reason they're quieter.

 

Anyway, that's my tuppence worth. Go for it, I've had another fitted on our new boat (running a Beta Marine engine).

 

 

Cheers,

Chris.

ps: should be meeting Esthers new owner at the weekend on her "new boat", will take some pictures then if I remember...

[pmms]

Noah

 

If you live near Northampton contact Servias silencers, they manufacture hospital silencers and will sell to you at the factory gate, give them a detailed drawing or better still a mock up of what you need,( a friend of mine made his out of wood and chicken wire) including the pipework and they will give you a VERY competitive quote. they will need engine details. Sorry I dont have their phone No on me

 

HTH

 

Paul M

[Noah]

Noah

 

If you live near Northampton contact Servias silencers, they manufacture hospital silencers and will sell to you at the factory gate, give them a detailed drawing or better still a mock up of what you need,( a friend of mine made his out of wood and chicken wire) including the pipework and they will give you a VERY competitive quote. they will need engine details. Sorry I dont have their phone No on me

 

HTH

 

Paul M

Thanks Paul, I would follow your advice if I was in that area and I could take in a "template." I'm in Lancashire so TW Marine are reasonably local although at £128 inc VAT, are quite expensive.

 

Noah

[bottle]

Thanks Paul, I would follow your advice if I was in that area and I could take in a "template." I'm in Lancashire so TW Marine are reasonably local although at £128 inc VAT, are quite expensive.

 

Noah

 

Hi Noah

 

To me this does not seem an excessive price, have you tried to get an ordinary one for a car lately?

 

Just had middle and rear section (both with boxes) fitted to my car £119 and £120 respectively and only guaranteed for two years.

[rallyfan]

Silencers, what are they? I havn't got one fitted to my 8 litre twin diesel. At tickover it just emits a gentle waft of exhaust gas and at cruising revs ( 280 rpm !!) it makes a lovely "kler-donk, kler donk" sort of thing.

[Noah]

Hi Noah

 

To me this does not seem an excessive price, have you tried to get an ordinary one for a car lately?

 

Just had middle and rear section (both with boxes) fitted to my car £119 and £120 respectively and only guaranteed for two years.

Your right, I'm just being a tight Rs! I once paid over 800 quid for an exhaust system for my bike. So, I'll buy one off TW Marine as soon as I've removed the old one and measured up for fittings that I'll need.

 

The soundproofing that I bought off TW has worked really well compared to the old carpet underlay that I had before. Only one problem was that I used contact adhesive (Evostick's new type) and in the heat of a long cruise in hot weather it softened and the sheets fell off! I've now fixed them on with screws and "mudguard" washers.

 

Noah

[awatsonbcp]

Noah

I had exactly the same problem with my soundproofing from TW.I am screwing it back on with stainless steel screws and washers as we speak!

[Noah]

Noah

I had exactly the same problem with my soundproofing from TW.I am screwing it back on with stainless steel screws and washers as we speak!

I could hear my engine getting louder and louder as the three sheets of insulation under the deck boards fell off. By the time I realised what was happening, one sheet had got mangled by the fanbelt and pulleys!

 

Noah

[bottle]

I once paid over 800 quid for an exhaust system for my bike

 

I expect that was a lovely, shiny chrome one.

 

You could always ask TW if they would chrome the 'hospital' silencer, you could probably beat £800