Hospital silencer

[tomandsophie]

Is it worth fitting a hospital silencer instead of a standard one? Our engine is going in next week and I've been quoted around £100 for a standard silencer for our Beta Greenline 43bhp engine, and about £150 for a hospital silencer. Is it worth spending the extra £50 or so?

Tom

[NB Willawaw]

Considering the money that you have spent on the boat, can you afford to take the risk for £50 extra.

If you buy the cheaper silencer, you will always be wondering, when you have to shout over the noise of the engine, whether the hospital silencer would have made an appreciable difference.

 

My understanding of hospital silencers is that they are just a more effective silencer.

I do not believe that there is a minimum specification for them as such in order to earn the title "hospital", so its very hard to measure their effectiveness unless you have them running side by side with a normal silencer.

Also, noise is very subjective.

 

We have a B43 greenline (good engine by the way) with a normal silencer but good sound insulation in the engine bay and I wouldn't call the noise excessive, but then I'm used to older boats with older engines and don't expect to have conversations with skippers of other boats without throttling right back to a tickover.

 

What is your expectation ? are you going to have to run the engine at a mooring to get electrical power ?

 

Best Regards

 

Mark

 

P.S I don't think hospitals are very quiet. If they made a library silencer or a graveyard silencer, then that would get my attention !

 

 

Is it worth fitting a hospital silencer instead of a standard one? Our engine is going in next week and I've been quoted around £100 for a standard silencer for our Beta Greenline 43bhp engine, and about £150 for a hospital silencer. Is it worth spending the extra £50 or so?

Tom

<{POST_SNAPBACK}>

[Gary Peacock]

Yes fit one.

[DHutch]

Considering the money that you have spent on the boat, can you afford to take the risk for £50 extra.

 

Go for it, your going to be standing almost directly ontop of the engine/exhast for hours every day you go crusing, and you really ourt to make the most of it.

- We take it quite gently, so often get other narrowboats behind us, and the one thing that always gets be is how much quiter it is once they've over took!!

- I'd say, the quiter the better, if you could get it even quiter, for £200, i'd still go for it, even if meant saving else where.

 

 

Dainel

[rog guiver]

We were going to fit one to our new Beta 43 but the installer suggested it would take up a lot of space. The silencer is positioned to the rear of the engine, exiting on the port side. He suggested that a hospital silencer would have to be placed across the back of the engine with the exhaust exiting through the starrboard side

Even without it the engine is much quieter than the Lister LPWS4 that we had in the last boat (with the same soundproofing).

[Gary Peacock]

A lot of engine installers don't like hospital silencers because they make work, they will need to adapt the standard installation kit and almost certainly fabricate and weld brackets most just don't want the hassle.

 

Gary

[dor]

For £50 extra I would go for the hospital silencer, but exhaust noise is not the only noise to concern yourself with.

 

My cruiser stern has aluminium treadplates for the floor. Stuck to the underneath of the plates is a sound-absorbing foam sandwich - the sort with different densities and a sheet of ?lead? embedded in it. It was like that when I got it, so don't know how noisy it would be without it, but I imagine it would be very disturbing.

 

The other thing that cut the noise a lot was fitting a Python drive coupling (similar to aquadrive). By taking the thrust off the engine bearings it made quite a difference to the noise transmitted to the hull.

[John Orentas]

The Hospital silencers are a very good quality but:

 

When I bought the silencer for my boat, I simply found a friendly exhaust system wholesaler, wondered around his place looking at the stock until I found one just the right size.

 

Get the biggest one that you can fit in the space but don't be limited by feeling the need to take the outlet out at the stern. Mine emerges 9 feet forward of the steerer's position giving loads of space for the silencer also the exhaust fumes and noise are a long way off when you are steering.

 

Note when you are selecting a silencer, try to find one that was designed for a diesel, some petrol engine ones have small internal holes and are prone to blockage when used with a diesel.

[tomandsophie]

Thanks for all the replies everybody- it's all useful advice. Keep it coming if you have any more ideas...

[Yamanx]

Depends on what you want.

 

My boat makes more noise elswhere in the drive, gearbox, engine etc than exhaust note. I have to hang over the back to hear the exhaust! Some people like the silent boat with no noise at all, others, like me, like an engine sound.

 

I love the "thup, thup, thup, thup" sound of a very slow reving engine making its way along the canal. So my next boat, or at least a boat I'll have one day, will have this kind of motor.

 

I'm still learning a lot about canal boats. At first I always liked the luxury semi trad style boat that, probably, attracts a lot of people to canal boating. But now I'm more inclined to the Tug style boat with the engine room and long forward deck, can still be as comfortable inside but there is a compromise with space I imagine. But, hey! its all about your choice and needs.

 

Great though eh? When that tug comes, thup thup thup thup past, crikey you can count the revs! Cant be more than 80-150rpm, excellent!

[DHutch]

Great though eh? When that tug comes, thup thup thup thup past, crikey you can count the revs! Cant be more than 80-150rpm, excellent!

 

Yeah, there was a guy at tarleton who was fitting this engine that he could pull down to about 55rpm, beutifull. Apprently he "found" it somewhere coupled to this 4.7KVA 240v threephase alternator, made as a pair. And when he took the brush cover off the the alternator it still had the casting marks on the slip rings!

- You'll never beat us tho! - our engine is quite happy at half that!

 

- Somtimes you need the rev counter to see if its still turning over!

 

 

Daniel

[Amicus]

I helped to re-install a re-built single cylinder engine in an elderly motor yacht, driving an alternator. I think it was a Gardener, I remember the handbook called it a “Laboratory Engine” it was Gardener grey anyway. Fascinating thing, to hand start it you slowly wound it up to about 20 or 30 rpm, dropped the de-compressor and away it went,……….chuff………….chuff……….chuffff maxed out at about 60*, huge fly-wheel. The whole thing stood about five feet tall!

 

*I think, twas a while ago

 

 

edit; just did a google, much faster than I remember

http://www.gardner-marine-diesels.co.uk/engines_1L2.html

Edited April 19, 2005 by Amicus