Will this work?

[blackdove1256]

I have a 1977 Atomic 4 on my Cal 30. The old standpipe exhaust system bit the dust or rust! I want to run a dry pipe from the exhaust manifold and then use the raw water exhaust as the coolant. This will run directly overboard, no muffler, etc. I have sufficient fall (slope) from the engine exhaust water to ensure no backflow. Pic attached showing the assembly.

Basicially the same as the MMI Catalina preassembled exhaust but with a 3" pipe turning outboard from the engine exhaust flange.

Any thoughts on why this won't work? Many thanks.

Gregg

[zellerj]

Without a muffler, it would be really loud. Why do you want to do this, a muffler is pretty cheap. I have been using the cheapo Vetus for 18 years - no issues. They are only $120 or so.

Is it because the exhaust hose is difficult to route?

[Mo]

Hi there,
This is an edit from my previous post. I didn't recognize the orientation of the pic at first. From what I see you are well protected from water intrusion although I think I would have gone with a hose to a vetus muffler down low and just rubber pipe out from the muffler. The life expectancy of black iron pipe is 3 to 5 years as well...the less the need to replace on that stuff the better. Every piece will be rusted after the portion near the manifold gives up the ghost. The section near the manifold goes first because of the constant change in temperature.

[ndutton]

More than one way to skin a cat

Gregg, it will work fine. The same design has worked successfully on Catalina 27s for 47 years. A couple of things to consider though:

• Hot section insulation. Be very careful to insulate sufficiently. It's the only protection you have from burning down the boat and you have a LOT of hot section to insulate.
• The downhill nature of the system from the water injection point to the transom while hard on port tack, rails under, either tack for that matter.

You said the engine was a 1977 but what year is the boat? My recollection is the last 30 footer produced by Cal was somewhere around 1973 - 74, a few years earlier than your engine.

[Al Schober]

Use plenty of insulation. The exhaust system can give off a lot of heat - particularly when it breaks! Photo shows a bilge blower after a broken exhaust incident.

[joe_db]

You need a LOT of wrap. 2 layers would IMHO be minimum.