Challenger drawings; cockpit, engine installation details.

[TomY]

I don't know the age of my exhaust but it appears to be exactly as designed. It works great but runs the risk of flooding the engine when the inner pipe corrodes through. I scanned this area to get an idea of how I will plumb in a new one with a water lift muffler. Has anyone installed a new exhaust system? What are the odds this is the original exhaust now on it's third engine. You'll notice the shapely tiller that came with some Challengers.

This drawing scan may help others with cockpit details. I'll continue to add these scans as time permits.

 

[southport]

Tom I'll look at ours- there is a water lift muffler and I'm pretty sure it's next to the shaft but I'll check.

 

[rjoconnell]

Tom,

Whisper has a water lift muffler that sits in the center above the prop shaft just aft of the stuffing box. It was added when a Perkins 4.108 was installed around 1980. I will take a photo when I next go to the boat (waiting for it to warm up a bit...).

Rick

 

[Bill Merrick]

Tom,

I went throught this about two years ago with my Mistral. Basically it's the same configuration down there and the Mistral drawing from Alden show the same original exhaust configuration as the Challenger.

The old exhaust system ( and engine ) had been removed when I got the boat and I couldn't fine the water-jacketed exhaust hose as originally designed for the boat. After looking at a lot of different configurations, I installed a set-up that Rick discribed. I fiberglassed in a pair of supports on the hull several inches above the prop shaft tube. This made it possible for me to screw in an approximately 8" by 10" by 1/2 " fiberglassed plywood shelf to hold the waterlift muffler. I was able to trim off the edges of the bottom flange of the muffler to fit it as far aft as possible so I could get at the shaft packing without removing the muffler. I can do that but it isn't easy. I have a Westerbeke 4-108 and because the engine sits well below the waterline, you need to have a riser in the exhaust to bring the exhaust cooling water into the system above the waterline. Otherwise you risk the chance that water will siphon back into the engine. I assume you know all of this and it is well covered on the installation instructions for the waterlift muffler.

Vetus makes a retangular, flat sided muffler that looks like it would be a much better fit than the round ones. But the plastic on that muffler seems quite flimsy and if you read the paperwork that comes in the box, it will tell you that the plastic should not be subjected to temperatures above something like 155F. If you ran your engine for any time at all without cooling water, you could very well loose the system. Even the heavy fiberglass mufflers like the Vernlift have a limited temperature range but at least they made them out of a temperature tolerant material and they obviously have stood the test of time.

I'll take a picture if I get to the boat and send it.

Good luck.

Bill Merrick
S/V Carmina
Seattle WA

 

[TomY]

Thanks for all the info. I'd be interested in how these water lift mufflers were fit below the cockpit sole. Bill, the designed water cooled exhaust is actually two pipes (copper?), one inside the other. The ends are then welded shut to the cooling enters just after the engine and exits just before the muffler with threaded fittings brazed to openings in the outer pipe. This whole thing is bent to the shape shown. I would imagine it would be costly to have it built again.

 

[Bill Merrick]

Tom,

Here are some pictures of my setup. Hope they help. Again this is the setup on a Westerbeke 4-108. The engine exhaust is on the port side. The current riser is galvanized cast iron pipe. I will probably replace that with welded stainless eventually but the cast iron, like in a car, is good for a long time. The stock water inlet elbow from Westerbeke is aluminum.

Bill Merrick
S/V Carmina
Seattle WA

 

[TomY]

Thank you Bill, that's very helpful. Can you tell me if you put a high loop in the hose before you exited the stern?

 

[Bill Merrick]

Tom,

Not yet.

One of the design flaws with the Mistral is that you cannot get to the exhaust gate valve or hose clamps at the transom. In the next few months I will be cutting in some hatches on the aft deck to get access so I can remove the old gate valve which is probably frozen, and install a U fitting in the hose about 2 feet from the transom thru-hull. One of the hatches will then be used for a propane locker.

Bill