Ann I am not a sound engineer but have played around with the subject a bit and got our old boat reasonable quite. Noise is transmitted in three ways from the engine to the listener.
Directly through holes in the boat which allow the sound waves to travel in air to the listener from the engine and from the exhaust. Indirectly the sound waves from the engine cause bits of the boat to vibrate a bit like a loudspeaker. From Vibration where the movement of the engine and associated bits causes bits of the boat itself to move. The engine needs air to breath and for cooling so to reduce direct transmission you need to fit air silencers on all air inlets and outlets. These can be as simple as a labyrinth or specially designed for the job. The important thing to remember is they all reduce the air flow so you need to make certain you do not reduce the effective size of the holes too much especially on an air cooled engine. Change the silencer for a water cooled or hospital type will greatly reduce the noise from the exhaust. Indirect noise transfer can be reduced by sticking special foam type material to the underside of the floor and the vertical surfaces. I can't find the supplier I used on Pajant but there is a firm advertising in Waterways World. All you can do about vibration is to check you have the correct mountings for the engine and that everything is tight and aligned correctly. Trust that is of some help. Paul NB The Rosery (if the new boat co ever get round to delivering) Ann wrote: > Here I am asking for help and advice again :-) > > The restoration of Bluebell is continuing (see > http://www.bridge19-40.org.uk/ link New Boat) and now that the engine is > running, we realise just how noisy a Lister in a cruiser stern with > absolutely no sound insulation is. The boat will be used as a community > trip boat and it would be nice if our passengers could actually speak to one > another :-) > > It is obviously going to be an expensive job to do a proper sound insulation > job but we hear that a cheap and nasty solution might be a waste of time > and money. > > Can anyone give any advice on what we should use and if anyone has solved > this problem before, we would love to hear from you. > > Thanks a lot, Ann > > Ann and Iain Street > NB Gamebird; One tenth NB Copperkins11 > Web site http://www.nbgamebird.co.uk > Scottish Inland Waterways Association - http://www.siwa.org.uk > Bridge 19-40 Canal Society - http://www.bridge19-40.org.uk > > > > > > Yahoo! Groups Links > > > > > > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/canals-list/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
