What is this thing found on exhaust?

[joedeg]

HI, this is my first ever post.

Just got a new to me old boat. She's a Biscay 36. I launched it and got to the marina Ok, how ever there was quite a good amount of exhaust fumes coming from the engine area which is practically in the main saloon. The exhaust needs replaced I know this but I discovered this 'thing' on the exhaust and I can't find exactly what it is. My suspicion is that it could be a vent of sorts, and maybe it also supplies water to the prop for cooling as I know the prop allows water flow from inside the yacht to the outside as was the case when I tested it on the dry. I haven't had a chance to further investigate but I took this picture anyway. Another note is this sits above and to the rear of the engine and is well above the waterline.



Could someone let me know what this is?

Thanks, Joe

 

[Pye_End]

Anti syphon?

 

[PetiteFleur]

As mentioned it's an antisyphon - I have one on my boat(not that design). Water comes from the heat Exchanger, through the anti syphon and then into the injection elbow. The small copper pipe at the top will go to an outlet on the transom and when engine is running there is a small jet of water exiting. This water jet can be directed into the cockpit drain so the helmsman can see the pump is working ok. Mine had an antisyphon valve which I removed as they can block up and then water could run back into the engine, so I fitted the pipe to the transom.

 

[scottie]

i think that it is a bit more than just an anti syphon
Commonly known as a “Parsons silencer” it is device from the 50/60s that predates the current exhaust elbow and combined a dry exhaust and eventually water cooled exhaust pipe
A substantial asbestos lagged pipe with a flexible antivibration insert ran from the exhaust manifold into the “”silencer”with a custom fabricated jacketed copper pipe joined to the skin fitting
This all cost a fortune in time materials and skilled labour
You can see the original pipes in your photo
Moving to water injection exhaust bends and rubber reinforced hose simplified the set up along with water traps and external anti syphon valves l !
The box itself was normally cast iron but the exhaust pipe had a relatively short life and not too many people want to work with the cotton packed “asbestos “lagging

 

[joedeg]

Thanks all, and interesting. I just got back from the boat today and I had a look. The hight and shape say its an anti-syphon. The copper pipe goes to the prop 'housing' to force cooling I guess and I found the exhaust leak. There is material around where the elbow meets the exhaust parts which I thought was some sort of 'Teflon cotton looking bandage thing' and thats where the fumes are comming from. I guess it might be that it's Asbestos, I am sure it comes in wide varieties of form. What does anyone think about a relacement material? I was thinking exhaust silencer wadding, although I don't quite know the properties of this material but it is pretty inexpencive which is great. I am thinking heat, water and will it stay in place will be the factors I need to consider in this job.

 

[alahol2]

Looks very much like fibreglass exhaust wrapping. It isn't too expensive.
You wouldn't normally need wrapping on a wet exhaust.

 

[scottie]

We have moved on from asbestos for lagging for health reasons

Be careful that what you replace it with as there is a major risk of fire if it is cotton based

You need specialist advice on this cheap is dangerous