Catalina 30 TRBS #2889 "Northern Light"

My exhaust pipe unexpectedly broke away from the engine while motoring in to the dock to replace the engine mounts under my 5411 diesel. Not bad timing, actually. I ended up replacing both exhaust system and engine mounts at the same time.

EXHAUST and COOLING...

I was tired of hearing from well-meaning boaters that my "water pump impeller is damaged," tired of smelling the exhaust mist that follows the boat, tired of the grime on the transom that builds up so quickly, and tired of the hot exhaust pipe that raises engine compartment temperature, so I completely reconfigured the exhaust and cooling system.

OLD EXHAUST PIPE

The photo of the old exhaust pipe is self-explanatory! When dropped on the concrete floor the old exhaust pipe shattered into little more than a pile of dust! The fiberglass insulation and wrapping had covered up the true condition. I think the pipe had been leaking for awhile, if the grime in and around that area of the cabin was any indication.

EXHAUST

A crowbar easily removed the stock Catalina muffler.

The Vernalift muffler was installed on the bed of the old muffler. Two stainless screws through it's flange hold it in place.

Vernalift #1500020 side-in-top-out muffler. 1-5/8" inlet and outlet.

The outlet connection nicely fit the existing outlet hose. It was as simple as tightening the two stainless hose clamps on the hose.

I installed new galvanized pipes from engine to muffler. The manifold outlet has a short nipple and 45-degree elbow followed by a sloped five-inch nipple, 90 degree elbow, and horizontal four-inch nipple (all 1-1/4" standard plumbing parts) aiming toward the muffler inlet.

The gap between pipe and muffler is bridged by a six-inch silicone hump hose obtained from Catalina Direct. 1-5/8" I.D.

I brazed two water inlet ports on the sloped five-inch nipple, so water is injected immediately on the downslope from the engine, not just prior to the muffler as on the original system.

This is the total system of manifold outlet (wrapped in fiberglass tape due to heat,) galvanized pipes, water injection, silicone hump hose, and muffler.

COOLING

I removed the "recirculation tee" on the thru-hull and installed a single hose barb. I hosed from there to the inlet strainer, from there to the water pump, and from the water pump up to the anti-siphon valve under the sink. Since leaks or breaks in that much of the system could sink the boat, I used reinforced hose and made these three runs as short and protected as possible.

I checked and cleaned the anti-siphon valve in light of Bill Rogers' experience with siphoning and hydrolock, etc, as posted on the SailNet email list in July 2005.

On the outlet side of the anti-siphon valve I routed the hose back down to a tee.

• One side of the tee (left side in the photo) has a ball valve through which part of the cooling water is hosed directly into one of the two water inlet ports on the exhaust pipe.
• The other side of the tee (right side in the photo) is hosed to the inlet side of the engine. The outlet side (top of the thermostat housing) is hosed to the water heater. Thus, the thermostat still regulates the engine temperature. The water heater return hose is connected to the second of the two water inlet ports on the exhaust pipe.

RESULTS and NOTES

1. Only two inches of the exhaust piping is hot (and is fiberglass wrapped to prevent burns.) The remainder is cool enough to touch when underway.
2. There is plenty of water spewing from the transom port. The water pump has plenty of excess capacity.
3. There is little smoke or mist.
4. The exhaust doesn't smell like it used to.
5. The transom remains cleaner (but never perfect.)
6. The purpose of the ball valve is to slightly restrict the water flow on the one side of the tee so that engine gets adequate water when the thermostat is open and is able to control it's temperature over all corners of the operating envelope. It's adjusted so that at both idle and full throttle the engine temperature stays at the thermostats temperature.
7. The silicone hump hose is quite effective at insulating engine vibration from the muffler and hull. It's flexing mode in my installation is axial (alternating slightly lengthening and shortening as the engine vibrates, which is what it appears to be designed for.)
8. With new engine mounts and new exhaust system, the noise is significantly quieter...enough so that it's now evident that another significant noise source is the air intake at the end of the "air cleaner" which will be my next project before insulating the entire space with Sounddown foam sheets.

CAVEAT

This solution and configuration is probably not for everybody. Your mileage may vary.