Exhaust Plumbing

[Unregistered]

Although my exhaust plumbing never had one, based on some of your comments I am considering adding a shutoff ball valve between my waterlift muffler and above w/l thru hull. While under power the rump of the boat settles down with the outlet under water...not a problem with exhaust pressure. What I want to prevent is water entry in a following sea while sailing even though there is an adequate 18" rise (loop) between the outlet and the muffler. The question is that most ball valves have a much smaller ball orifice that will probably restrict exhaust flow. Would you recommend a larger 2 or 2-1/2" valve with reducing bushings back to 1-1/4".

It is a lot of pricey bronze hardware I would like to avoid if not necessary.

Your expertise would be appreciated..Thanks!

[Don Moyer]

I think your instinct to avoid a lot of pricey bronze is the correct one.

I'm not hearing you say that your engine has ever suffered any intrusion of raw water from following seas, so I would have to assume that your exhaust system (as designed) has adequate protection from this concern.

Our historic concern over water intrusion into the engine from the exhaust system is based almost entirely on the engine cooling water itself backing up into the hot section of the system.

[dduelin]

Because I had the same concerns over seawater intrusion in a following sea, 5 years ago I installed a quarter-turn ball valve in the exhaust hose just before it exits the boat. The Morgan 30 has the exhaust outlet under the counter and when sailing fast the outlet is well the waterline. The exhaust hose has a high loop in it, but there isn't alot of freeboard with this boat, and when heeled on starboard tack the top of the loop is just inches above the standing quarterwave. Now and again I race several hundred miles offshore as well as shorter passages and sometimes am at sea for a couple of days. Even a small amount of water lapping up and over the loop might eventually have bad consequences by filling the muffler. It probably wouldn't happen, but in the right circumstances it could. When we clear the inlet, the valve is shut and I hang the ignition key on the handle. I learned this when the engine would not start one fine day. Remember the old prank of stuffing a potato up a car's exhaust pipe?

To do this I bought a full flow 1.25" all stainless steel ball valve. It has a bore of at least 1.25" thru the valve. It connects to the rubber hose on either side with nipples with the threaded ends cut off and inserted in the ID of the hose, then hose clamped. I think the hose is 1.75" Sheilds 250. At a retail marine store a valve like this would cost too way too much, but I bought it at an industrial valve supplier that sells pipe and fittings to the commercial ship building and repair trade and it was $25. Bronze would have been less. Two years ago when I bought the bronze fittings for the exhaust manifold I made it cost me about $35 total. I was tired of replacing galvanized every two years.

Dave Doolin
1969 M30 Angel's Wing

[Peter Wanka]

Funny you mention Exhaust System. I am just in the process to replace mine with 1 1/4" SS pipe 316 steel. From the local supply house in Boston for about $100,- . Boat is a 1976 Tartan 34C with a waterlift muffler. peter wanka

[ericson_35]

Another consideration is a flapper valve on the outer hull/exaust exit point . Although not the greatest solution, it is certainly an easy one and not all that expensive. Or simply raise the outlet next haul stern to the dock. Otherwise, some type of valve if you are highly concerned (just have to remember to open it when you need the engine in an emergency!). We used butterfly valves on the bigger boats as they have the least restriction when open, are easily repaired and usually have notches for postive locking in a variety of positions. Other wise it's the old jungle gym of plumbing parts and adapters.

Personally I put a good goose neck in the flexible exhaust hose at the transom in the lazzie in adition to the riser in the cockpit locker. In combination with a aqualift style box, I'm not too concerened with any flow back, but the Ericson 35 exhaust outlet is well above the H2O line.

John

[john]

I have a 1967 Pearson Vanguard which has a high cut-in transom where the exhaust exits the hull. The previous owner, a very good friend of mine, had to have Don rebuild our A4 because of heavy seas on the transom getting into the manifold while in port! He installed a full sized valve as a through-hull fitting in the lazarette locker. Also, we installed a back-pressure relief valve, around $9 at West Marine, in the seawater cooling loop after the heat-exchanger to prevent damage to the pump and/or raw water getting back in the engine if the exhaust valve is left closed and the engine started. I don't know about anyone else but this was a really good idea on our boat as I've done it twice!
John Donegan

[Tartan 34C]

Funny you mention Exhaust System. I am just in the process to replace mine with 1 1/4" SS pipe 316 steel. From the local supply house in Boston for about $100,- . Boat is a 1976 Tartan 34C with a waterlift muffler. peter wanka

Peter,

Were you able to have the flanged (which fits to the manifold) easily welded onto your SS pipe? Or did you have a better solution for replaceing the pipe and flange together? Ours rusted through this weekend and needs to be replaced. Thinking of doing ourselves instead of having our marine machanic provide the service.

Thanks.

[dvdcnl]

I had a yankee 30 several years ago that had the standpipe exhaust system. The inner exhaust pipe developed a leak and water ran back and ruined the engine for the po.

On my columbia 29 with a standpipe system, there is a 't' on the nipple coming out of the manifold. I screwed off the cap on the downside drain nipple and installed a ball valve. When I shut the engine down, I open the valve and check for any water indicating a leak in the exhaust pipe.