Standpipe Exhaust for Diesel

[lady sophie]

My 33' cutter has a midship Universal 35. I need to install a waterlift/muffler. I have a deep bilge and was thinking of making a standpipe type system. Any thoughts on this or ideas as to design? I understand standpipes were common before commercial waterlift mufflers were available but can't find any designs of the internet that I can fab from.
Mil

[ssullivan]

A start:

Standpipe Exhaust

[lady sophie]

Yes I had read that. It was a posting on the Alberg forum. I researched the web via Google several times. I was hoping to uncover a design drawing rather than a narrative description. It is helpful tho and I have sketched up what I think is described and have given it to a welder to fab. I was hoping that someone on this list may have first hand experience with this system.
Thanks for the response,
Mil

[Chief Engineer]

What kind of exhaust system was in there before?

Why do you feel the need to re-engineer it?

[lady sophie]

It must be a professional defect. I am a multi-state licensed PE and started my career 30 years ago with Delco Remy - the battery people - as a machine designer. I think in drawings I guess. My search was more to uncover anyone that had first hand experience with a standpipe type exhaust system. Do they work well, etc. I also investigated - via Google - the split dry exhaust sometimes called a "North Sea" style exhaust. Any comments on that one? The current exhaust is a water lift muffler located in the bilge below the drive shaft. The concern I have is that if it needs attention, the drive shaft must be removed. Maybe I should but this one on the don't worry about it pile.

[bob kingsland]

Ladysophie, I can relate: I like drawings, too. But in your case, unless the waterlift is stainless, it's probably better off in the don't worry about it pile. Friends have a stainless standpipe, originally custom built by some guy in NY who used to advertise... I think a 2" sched 10 inside a 3" sched 10, rings top and bottom, all welded 316. They seem to rot out after 8-10 years, and I've built 2 more for them since they launched, now 29 years ago. Built a 316 water lift for my own boat last year, mostly because I had a very constricted space problem and needed bottom in on the exhaust, bottom out on the water/exhaust discharge, and Centek doesn't make such a thing. I expect to have to rebuild it in 8-10 years, because stainless and hot salt water don't really mix that well. They're not very hard to make in stainless, but their longevity is a little suspect.
Best, Bob S/V Restless

[Chief Engineer]

When you are referring to a standpipe, do you mean the exhaust comes into the bottom of a vertical pipe----the water injected at the midpoint/or top of standpipe and then the exhaust coming off the top exits out the stern with the water? If that is what you want....I have had it in my Ericson for years w/o any problem.

[lady sophie]

I posted my original question of the standpipe a year and a half ago! I then took a long term assignment in China and just now getting back to my boat. What I have in mind is actually a water lift muffler rather than a standpipe. The exhaust manifold has an inection elbow for the cooling water discharge. I plan to bring the exhaust from the injection elbow into the top of the muffler. The infeed pipe will extend down to about 1" from the bottom. The discharge from the muffler will be on the side up perhaps 6". I would fab it in AL6XN as that will be much more corrosion resistant. Any comments?

[never monday]

Originally Posted by lady sophie

I posted my original question of the standpipe a year and a half ago! I then took a long term assignment in China and just now getting back to my boat. What I have in mind is actually a water lift muffler rather than a standpipe. The exhaust manifold has an inection elbow for the cooling water discharge. I plan to bring the exhaust from the injection elbow into the top of the muffler. The infeed pipe will extend down to about 1" from the bottom. The discharge from the muffler will be on the side up perhaps 6". I would fab it in AL6XN as that will be much more corrosion resistant. Any comments?

your fab design of the waterlift will cause an engine hydrolock. Please by a commercially available fiberglass waterlift. It's even more corrosion resistant than Aluminum.

[lady sophie]

Thank you for your response Never Monday.

There are several causes of hydrolocking but waterlift mufflers are not the culprit. Usually it is from overcranking when the engine doesn't fire up. The next one is a non-functional (or missing) anti-siphon valve. Improper installation is also a problem. I have seen some boats come from dealers that are set up to hydrolock if conditions were even slightly bad. I was on a Cal 30 a few years ago in a race in very bad conditions and we were heeled so badly that we had sea water intrusion and hydrolocked, but that is unusual.

The maximum exhaust manifold backpressure I can have on my engine, according to factory specs, is 41" WC. That is quite a bit. By my calculations I will have about 26".

You are correct, fiberglass is definately more corrosion resistant than aluminum. However I am nervous about putting fiberglass into an exhaust system - too many years working with equipment to know that worse case happens. AL6XN is a austenitic series stainless steel alloy developed for salt water applications. 304 should never be uses with hot salt water, 316 is only slightly better but AL6XN is a proven excellent performer.

[never monday]

Originally Posted by lady sophie

Thank you for your response Never Monday.

There are several causes of hydrolocking but waterlift mufflers are not the culprit. Usually it is from overcranking when the engine doesn't fire up. The next one is a non-functional (or missing) anti-siphon valve. Improper installation is also a problem. I have seen some boats come from dealers that are set up to hydrolock if conditions were even slightly bad. I was on a Cal 30 a few years ago in a race in very bad conditions and we were heeled so badly that we had sea water intrusion and hydrolocked, but that is unusual.

The maximum exhaust manifold backpressure I can have on my engine, according to factory specs, is 41" WC. That is quite a bit. By my calculations I will have about 26".

You are correct, fiberglass is definately more corrosion resistant than aluminum. However I am nervous about putting fiberglass into an exhaust system - too many years working with equipment to know that worse case happens. AL6XN is a austenitic series stainless steel alloy developed for salt water applications. 304 should never be uses with hot salt water, 316 is only slightly better but AL6XN is a proven excellent performer.

I don't appreciate your blatant attack of my knowledge.

good luck with your plan

[hpeer]

I don't know if this will help but maybe make you feel not alone. We just bought a new to us boat, steel, the Centec muffler was (as yours) in the lower bilge blocking access to the inside of the keel and the (non-functioning) bilge pump. With a steel boat you need to be able to access and maintain all parts of the interior hull, especially something that would retain water, and this was acting as a sump. So the muffler had to go. The motor and exhaust was replaced in 2006. I decided to have it redone by a mechanic as I didn't have the time or energy to take on yet another job. Wise decision or not it ended up costing a really big bundle, yet I don't know I would not have made a hash of it.

The muffler as installed was 3 to 4 feet below the exhaust, then there was a rise of nearly 7' (yes, 7') to a 180 deg turn out the transom. The engine had a seized turbo (rust) and, as it turns out, some very light rust on #1 piston. No damage but slight signs of rust. The engine had 690 hours total. So it appears that some water was back flowing into the engine from the exhaust.

To make the water lift muffler system work we had to relocate the muffler much higher. That required fabrication of a 14" exhaust riser before the water injection, then to a Vetus muffler, then out to a relocated exhaust via a silencer, check valve and Vetus goose neck. I still need to check back pressure but all seems to work fine, we have a much reduced lift and greater water capacity. So here's hoping.

The mechanic had a fabricator make the riser. He tacked it together and brought it to the boat to try it out and make sure if fit well and didn't interfere with other parts before final welding. No drawings were made but he had the max and min lengths he need. The riser seems to be fine.

[sildene]

I'm no expert, but it doesn't sound right that your inlet pipe reaches 1" from the bottom - I would check up on muffler design internals before building. I would have thought the outlet pipe entry pt would be lower than the inlet pipe (could also be one of Never Monday's concerns; he may not elaborate, but he's a professional, so I'd take some note).

Martin

[James S]

I built my waterlift from FG
The inlet goes into the top of the chamber...the outlet goes out from the side but it's pick-up extends down to about 1 inch from the bottom.
Given the location I was able to fabricate a riser that is the highest point in the system by 8 inches...this greatly minimizes the chance of getting water in the engine.

[sildene]

James, very nice fibreglass job. And gelcoat/paint job.

May I ask what materials you used for the dry riser -the pipe itself and the thermal cloth wrapping?

Martin