Yanmar 110 repower exhaust question

[Verboaten]

I'm having my boat repowered with a Yanmar 110. Changing the engine requires a re-design of the exhaust on my boat as the exhaust elbow is moving from the starboard to port.

Due to the usual space constraints and trying to not rebuild the entire engine bay, the new exhaust hose has a dip in it before it enters the muffler. This dip will trap water and I'm wondering how big of a problem this is. The muffler is still below the exhaust elbow output, but the hose will fill with water to its full diameter.

I've got a call in to the shop doing the work but I would like to know how hard I should push back if they blow it off as 'normal'.

Thanks for looking & I appreciate everyone's feedback.
-Cheers!

 

[Verboaten]

I'm looking at this image, with the big red X's on it...

 

[mvweebles]

I'm not sure I understand what the shop is saying or what is changing. But here is a good article on considerations and design elements.

"Please Don't Drown Me" proper exhaust system

Attached article from Bob Senter, technical advisor of Northern Lights. He describes basic marine exhaust systems and what to look for to keep your engine happy

www.trawlerforum.com

Peter

 

[Verboaten]

Engine, muffler and the 3"(?) hose in the picture are all newly installed - but not yet been in the water.

Thanks for the link to the article. I guess this is the salient point there:

"5. Make sure that there is no low spot or belly in the exhaust hose where water can be trapped and flow back into the engine when the boat pitches and rolls."

 

[Fish53]

How hard would it be to raise your mixing elbow? I can’t really see in the photo but it sort of looks like bringing it up 2 to 4 inches might fix it. It’s always good to get that elbow up as much as is convenient. My Universal uses simple 1 1/4 pipe fittings. One observation though is having the exhaust hose run athwartship, a roll is usually steeper than a pitch and could possibly get water in your engine with the boat at anchor or on a mooring.

 

[Keysdisease]

 

[Verboaten]

The cockpit sole is directly above the elbow, so it's not going to get any higher. I've also read that adding a 90deg elbow is not recommended in that bit of exhaust hose as it causes too much flow resistance, but I like the idea.

Today I saw the updated configuration and they've manhandled that hose to remove the "droop" and eliminate 90% of the standing water before the muffler. It's a tight bend with a 3" corrugated hose but the curve radius is probably double what we see in the 90 deg elbow shown above.

I think it's a good solution.
Thanks to those who chimed in!