Yanmar exhaust elbow dimensions

[differentroads]

I might well be mistaken, but it seems to me that the item that you consider buying
https://www.parts4engines.com/yanmar-3gm30-stainless-exhaust-outlet/
is of the wet type that this guy
https://www.sbmar.com/articles/designing-a-marine-exhaust-system/
warns about?
Perhaps it would be safer get a high riser of the type that Beta Marine among others offer, that is a "dry" uphill section with a lagging and the injection point /water jacket only on the downhill section?

Thanks. Yes, it is. And at £250+ , it's not a cheap thing to buy just to assess it. There's not a bespoke dry riser for the Yanmar that I can find, and he's pretty scathing about people making half baked attempts to fabricate their own. So I'm still not sure about that approach.

 

[differentroads]

This is good advice. If you follow the Vetus instructions you won't have a problem. You need a gooseneck on the exhaust outlet (either a moulded one or simply a big loop of pipe), plus a vent valve on the water injection point.

Cheers. Theres a siphon valve with a vent pipe fitted and it appears to work (a steady stream of water comes out when the engine is running but stripping it down to check is first on my to do list.

As I said to bikedaft above, I already raised to gooseneck at the aft end of this system thinking that seawater had pushed in through the transom outlet last year. But the problem repeated again this year.

 

[coopec]

The water is injected on the opposite side of the elbow. A bit more Googling and you'd have found a pic of it.

Thank you for that but that was pointed out in the first few posts of this thread! (but thanks anyway)

 

[coopec]

This is good advice. If you follow the Vetus instructions you won't have a problem. You need a gooseneck on the exhaust outlet (either a moulded one or simply a big loop of pipe), plus a vent valve on the water injection point.

According to the article

https://www.sbmar.com/articles/designing-a-marine-exhaust-system/
that is bad advice.

 

[coopec]

I reckon I'm pretty good at assessing people's expertise and from what you've said so far I'm surprised that you don't feel confident to undertake the modifications.

I worried too about getting hot gases into the Vetus exhaust but the water injected exhaust I designed seems to work fine though I've yet to run it for an extended period. Tomorrow (my bed-time now) I'll take a photo of my set-up and post it here. (I followed that guys instructions to the letter.) Cheers.

Well here are a few photos.

The exhaust mixer wasn't a real problem. I measured where the ss pipe had to come from and where it had to go then a made up a ply template with blocks of wood. I gave the SS tube (too long for the finished mixer to give me some latitude) to the Auto Exhaust crowd (who had the right equipment) and told them the finished job had to fit the template. The injector pipe extends almost to the other side of the mixer but it has several holes drilled as outlets as well.



I didn't like the way Vetus suggested mounting the goose-neck so I made up a couple of f/g moldings.





This is where the water enters the Vetus Waterlock. (Gearbox heat ex-changer in the foreground)