Diesel engine exhaust noise

[MochiCraft35Fly]

Dear all,

As a new member to this community I am seeking help from more experienced members.

I am a proud owner of a fairly old Italian motor boat, an 1982 Mochi Craft 35 Fly. Its primarily used for river cruises, as we are living inland.

The issue we are having is that exhaust noise is starting to bother us quite a bit. I am no expert in marine engine field, but it seems that my diesel engine (Aifo Iveco 8361, version with 270 hp) is not fitted with a muffler.

Is it possible to make it more silent by adding a muffler, how does one go about figuring out muffler type to install and how difficult of a project would it be ? Thanks for your help.

Best regards,
Emil

 

[PetiteFleur]

You could fit an inline muffler - available in various sizes to suit your exhaust hose, ASAP Supplies have a good selection. That should silence the noise - I'm assuming it is a water cooled engine.

 

[MochiCraft35Fly]

You could fit an inline muffler - available in various sizes to suit your exhaust hose, ASAP Supplies have a good selection. That should silence the noise - I'm assuming it is a water cooled engine.

Thanks for your reply. I took a look at ASAP Supplies website and found a number of inline mufflers that could be suitable. I will check with my local Vetus dealer about muffler selection criteria (besides the obvious exhaust hose diameter), since Vetus is available locally.

Thanks again and cheers.

 

[LittleSister]

Useful info and advice on exhausts in the Vetus Catalogue, page 81 onwards, especially the diagrams on page 85.
VETUS Catalogue 2019 - 2020 - English

 

[rotrax]

Within the last six months I have redone the exhaust system on our Kiwi boat, a Hartley 32 sailboat in steel.

It had a water trap which I at first assumed was a silencer but as the Bukh DV20 twin sounded like a motorbike crossing a deep ford I worked out it was not.

I removed the back part of the system, welded up the transom outlet, cut a new one much higher up and fitted a locally made silencer which cost about 45 quid.

Total transformation, really quiet, pleasure to use the engine now.

I found room to make a big upward loop so no watertrap required.

I found, 4 years ago, a big Halyard silencer on ebay for 100 quid. This fitted my genset install and just required sleeving down the inlet/outlet from 75mm to 50mm. I used sillicone rubber motorsport connectors for this, not expensive and did the job perfectly.

Genset exhaust is Really quiet too- noisiest bit is the water splashing out of the exhaust.

You will get an idea of the size you require from the exhaust pipe size - choose a silencer with inlet/outlet of that size you wont go far wrong. If you find one that you like with bigger hose size, motorsport sillicone rubber step downs for turbocharging installs are readily available. Ebay is your friend....................

Good luck.

 

[LittleSister]

I found room to make a big upward loop so no watertrap required.

I'd have thought the bigger your upward loop the more (or bigger) you need a waterlock.