Water muffler questions

[rigspelt]

This old boat (C&C 27 MK II) has an Onan water lift muffler that is 12" diameter and 12" high. It has a side entry and center vertical exit. The base of the muffler is just above the base of the engine, so the manifold outlet and muffler inlet are almost on the same level (the pipe has to have a vertical loop built in).

The MMI SS muffler is only 6"x7" -- half the size. The hose run from muffler to transom is about 8 feet I think, including a 2-foot vertical rise before sloping back to the transom. So, would the smaller MMI muffler work?

[keithems]

like rigspelt here, i am replacing an onan waterlift muffler of about the same size; i have a c&c 30, not a 27, but the installation is pretty much the same.

i've noticed that west marine carries a waterlift of about the same size, as well as a smaller one a few inches shorter [almost the same size as in the mmi catalogue.]

if i get the smaller, will i incur increased backpressure? is there any reason i shouldn't downsize?

in other words, which would you all recommend, the smaller or the larger one?

thanks in advance, everyone....

keithems

[Mo]

Rigs,
I am close to you (shearwater yacht club). We have one C&C 27 here with an A4. My friend Skip owns it. I think the smaller MMI would work fine. If you get a chance you should email me; we can get a look at what's on Skips.

[rigspelt]

Hard to believe 3 years gone already. I ended up putting in that smaller Moyer stainless water lift and so far it has been working fine. After shut down there is about an inch and a half of water in the bottom. I have not measured back pressure, but I don't think that would be a problem. My main concern had been overfilling, but that concern did not "hold water", so I just "go with the flow".

[sastanley]

rigs, no kidding, remember when you and I were newbies to A4's & this great forum????

[Mo]

Sorry Rigs, didn't look at the date of your post..oops! Have a great summer there and I'll keep an eye out on my travels.

All the best.

[jpian0923]

Rigs, You installed the smaller one without waiting for a reply?? Blasphemy!

[David Masury]

In my C&C 27 I replaced the old steel aqualift muffler with a fiberglass unit (coast guard approved) that was smaller. I just made a pedistal out of plywood, epoxy coated, and matched the outlet height from the steel unit... works fine.

David

[gary gerber]

Do too limited space in the engine compartment I installed a Vetus water lift in my lazarette. I could not transfer the two photos but if you go to my album you can get an idea of the versatility of the Vetus unit. This unit has been in my sloop for over five years. I hope this is of some help.

[pallen58]

On my E29 I have what must be a standpipe muffler. I don't know the condition but I assume that it isn't new. I was planning to install the water lift muffler and feel I have the space to do that. I have been reading all the information on exhaust systems. Should I stick with a standpipe or can I switch to a waterlift. Which is a better system?
Thanks

[hanleyclifford]

If you have a standpipe system you should replace it; the water lift system is inferior.

[ndutton]

Pallen

How about a picture?

[Laker]

Pallen - I am on the standpipe bandwagon. In my opinion , which was formed on the wealth of knowledge I gained from this very forum , the waterlift is the alternative exhaust system for those boats which cannot accommodate a standpipe.

Hoping to finish my exhaust re-build today ,
Laker

[ndutton]

In defense of the waterlift

The waterlift is an excellent system that has been used successfully for decades. I'd guess nearly every sailboat built since the mid to late 70's, at least the vast majority, have the waterlift system. The reason we see so many standpipes among the members of this forum is our beloved A-4's were a very popular engine only up to the late 70's or very early 80's when the diesel movement took over. The a-4's popularity dates well before waterlifts became commonplace. Many of our boats, by the fact they even have A-4's, are older than dirt.

The naysayers have 2 valid arguments though, neither of which mean all that much to me:

1. A waterlift can backflood an engine through the exhaust if allowed to do so by a careless or inexperienced owner. Any regular on this forum knows better. This is similar to a boat sinking because the toilet thru-hull was left open. It doesn't mean toilets sink boats. A waterlift system won't do it on its own, it needs an accomplice.
2. Comparing well designed, maintained and serviceable systems, a waterlift will impart slightly higher exhaust backpressure than a standpipe. Same holds true for diesels yet there are thousands and thousands of engines with waterlift systems out there that run just fine for decades. Although technically true, history shows the elevated backpressure is minor enough to render it insignificant in practical terms. I repeat, for those who will inevitably take exception to this statement, we're talking about a well designed, maintained and serviceable system.

Why would so many builders install them? Well, due to a lack of available space they may have had no choice. Or the tail wags the dog, the introduction of the waterlift afforded designers more interior layout options not requiring the necessary standpipe space.
And yes, a waterlift system is cheaper.

So pallen58, if you decide to go to a waterlift system, you'll be in good company. Before you do, be sure you fully understand the dynamics at work to be able to design your system well. Problems with a poorly designed system (sags, traps, long uphill hose runs after the muffler) are not the fault of the waterlift system concept.

[ILikeRust]

Neil,

Can you point to some good resources illustrating proper exhaust installations? I'd love to see some diagrams and detailed instructions as to key required elements. Particularly as it will be the next thing I have to tackle after I drop the engine back into my boat (which I intend to occur before the end of July).

I need to take a good look at what's going on with my exhaust system, because I never have taken a good look at it yet. I know it's got a plastic Vetus waterlift, and I suppose I could just keep using that to save the money it would cost to replace it, but by the same token, since I haven't spared any expense in overhauling the engine, and I want to get all my boat's systems to a point where they are solid and reliable and I don't have to worry much about them, I'm thinking I might either convert to a standpipe or at least invest in a better-quality waterlift than the plastic bottle Vetus.

I'll have to inspect it, but I'm guessing there is a possibility I might have to replace it, or the exhaust hose, anyhow. Don't know what I'm going to find until I take a good look-see at it. Which I will of course report here...