1977 Catalina 27 Exhaust system

[nakfox@sbcglobal.net]

I've found two possible replacements to my hot exhaust riser; one with elbow and one with a tee with small pipe section extending down from the tee with a cap on it. What does the small pipe with cap do. Is it neccessary? Which kind to you have?
See photos.

[nakfox@sbcglobal.net]

Cat 27 exhaust with brown container

Attached is photo of what comes between my hot exhaust riser and the back of the boat. It looks like a brown plastic container. The hose from exit of exhaust rise looks to go into the top of the plastic container. Does anyone else have that pastic container or know what it is/does?

[ndutton]

What you have there is a Vetus gooseneck. It's purpose is to make a high loop just before the transom outlet, another protection against exhaust system backflooding.

http://www.vetus.com/exhaust-systems/gooseneck/vetus-plastic-gooseneck-type-lt40-40-mm.html

[nakfox@sbcglobal.net]

Cat 27 1977 Exhaust System

ndutton,
Wow, that is it! Great! Thanks!

[Don Moyer]

Do any other Catalina 27 owners have a similar water lift device just before the exhaust leaves the transom? It was my understanding that the original Catalina configuration had the exhaust going slightly downhill from the end of the hot section, and then directly through the transom through-hull. Don

[JOHN COOKSON]

Do any other Catalina 27 owners have a similar water lift device just before the exhaust leaves the transom? It was my understanding that the original Catalina configuration had the exhaust going slightly downhill from the end of the hot section, and then directly through the transom through-hull. Don

No such device. And the exhaust does go slightly down hill and through a hole in the transom. I found that I let the hose dip down a bit just before the transom exit some water pools in it which helps with noise control. Also I get batching at at low RPMs and a steady stream at higher RPMs - just like a "regular" exhaust sustem.
I purchased my Cat 27 hull #4446 from the first owner when the boat was 2 1/2 years old so I bought a boat that was in its original factory configuration.
It has no such riser. I've never had a problem with water comming into the engine from the exhaust ever.
That said I don't know what Catalina did of previous or future production runs.
The only way such a riser would be of any value would be if the riser was higher than the highest part of the hot section on all points of sail.
Side note to nakfox: My hot section looks like the one in the right photo. This is the original Cat 27 design. Use a union on a short nipple from the manifold flange and the hot section proper. It will make life easier. Send me a PM if you need help. This is easy to do - that is once you've done it. I've done it 3 times...........

TRUE GRIT

[67c&ccorv]

I've found two possible replacements to my hot exhaust riser; one with elbow and one with a tee with small pipe section extending down from the tee with a cap on it. What does the small pipe with cap do. Is it neccessary? Which kind to you have?
See photos.

Condensate drain and surge chamber for following seas...is it necessary - probably not but I think it a good idea in principle.

[Don Moyer]

We eliminated the nipple below the "T" from the original design mostly because no one in Catalina could remember why the nipple was there, and we could see no reasonable benefit for including it. Don

[nakfox@sbcglobal.net]

Catalinadirect.com help desk says "T" and nipple/cap it was for two purposes; 1. sound reduction and 2. water backup preventer.

[JOHN COOKSON]

Yes

Catalinadirect.com help desk says "T" and nipple/cap it was for two purposes; 1. sound reduction and 2. water backup preventer.

My guess always was that it is some sort of resonating chamber.
I've never seen any water in it. Maybe it evaporated.


TRUE GRIT

[ndutton]

Don et al,

To my best recollection NO sailboat manufacturer during the era of the Atomic 4 used Vetus exhaust products. Not a single one. I'm sure nakfox's installation is a P.O.'s or P.M.'s (previous mechanic's) handiwork.

There's a downside too. It turns the original Catalina 27 exhaust design into a quasi-waterlift requiring exhaust pressure to lift the water over the gooseneck to expel it out the transom. Nakfox, I strongly recommend removing the gooseneck and use a flexible external flapper instead (see pics), not to mention the risk of Vetus gooseneck meltdown if there's ever a raw water blockage and elevated exhaust temps.

[BunnyPlanet169]

To my best recollection NO sailboat manufacturer during the era of the Atomic 4 used Vetus exhaust products.

Bristol, at least in my small sample of knowledge, did not, and I'm sure they would have if the materials were available at the time.... There is no way my hand made copper double jacket would be cost effective. EDPM rubber, used in wet exhaust hoses and flat roofs was only developed in the '60s, and probably not commercially available till much later.

Vetus is in the business of selling parts to boaters. Check out this picture from their website - water lift, muffler, and gooseneck. What does the gooseneck do that an elbow or hose doesn't do? Sell goosenecks!

[marthur]

In answer to Don'a question, we run a plastic water lift muffler after the hot section on our '77 C-27. We added it for noise reduction. It really works well. We have run it for 11 years and 900 hours. That has included lots of rough weather and numerous 18 hour motoring runs.

[Easy Rider]

My boat came with a PO installed Vetus water lift muffler and I've being running with it for 27 years without any problems (so far). I have wondered about backpressure but since my exhaust has being trouble free other than replacing a few hot sections I'm gong to leave it there for another 27 years. It's so quiet I love sneaking in and out of the marina with only the sound of the batching water leaving out the transom outlet.

[marthur]

It's so quiet I love sneaking in and out of the marina with only the sound of the batching water leaving out the transom outlet.

+1

Oddly enough, the motor is many times louder down below than it is outside of the boat.