Exhaust Shut-off Valves

[Christian Van H]

Hi All! I'm replacing my exhaust hose and fittings right now. All hose is 2 7/8". I have found hose, a 90 deg elbow, and the correct straight hose connectors, but I want to install a ball shut-off valve of some sort right inside the transom to close the system during heavy following seas. Any ideas about valves that wont break the bank? Thanks, Chris

[r.furborough]

Why not just use a flapper on the exhaust outlet. That will help in a following sea and will not get overlooked or eventually not used.

[Christian Van H]

I see your point, but I'm not sure it's enough protection. I understand what you mean about overlooked and not used though...

[delmarrey]

If your worried about following seas then you need to re-plumb your exhaust. Here are a few options.

[Christian Van H]

Wow Del, that was a lot of info. My boat uses a modified wet exhaust system unlike everything just posted, and has worked just fine for over 30 years. I just want the ability to shut off the system from following seas...something that Nigel Calder recommends, Anyone using a large valve out there?

[cal40john]

Originally Posted by Christian Van H

Wow Del, that was a lot of info. My boat uses a modified wet exhaust system unlike everything just posted, and has worked just fine for over 30 years. I just want the ability to shut off the system from following seas...something that Nigel Calder recommends, Anyone using a large valve out there?

Both a friends Cal 34 I used to sail and the Cal40 I have now have a shutoff valve. I'm fairly sure I remember some of the other Cal 40s in the area have them as well. Came with the boat, so I have never priced one. My Cal 40 also has the flapper valve. I have only used the valve, other than exercising it, on the Cal 34 a few times. Once in the Straits of Georgia, and a couple of times on a Hawaii trip years ago.

John

[Hud3]

Christian,

I installed a flapper valve on the exhaust fitting after my first offshore passage. In following seas, I could hear the water running up the exhaust hose. It never got to the engine, but it worried me. The flapper valve solved the problem, completely. It slams shut when a wave hits it. Simple, cheap and foolproof! Emphasis on the foolproof.

[Oceansandmts]

Don't yet know how well it works, but the new boat has a Forespar 2" valve in the exhaust located in the high loop just before the transom. It is close to centerline and in the cockpit coaming, so I was able to arrange it so that the handle covers the on-off switch for the engine when the valve is closed. Since you have to open the valve to turn the engine on, there are no problems remembering to open the valve before starting!

A 3" valve is not going to be cheap, but it is probably like a lot of safety gear and arrangements: Probably never need it, hope you will never need it, but if the day ever does come you will really wish you had it.

[Joli]

Well, we had a valve on the exhaust that was inadvertantly left closed when we started the engine, made a big bang when the muffler exploded. We now use a flapper and have a loop well above the waterline.

[westsail42]

We have a ball valve inline with the exhaust system on our 28 footer, with a Yanmar 3GMF. The valve is just before the transom exit. Marelon. Have not had any problems. It is just now needs some lubrication after ten years.

With goosenecks and waterlift mufflers, you need to watchout for excessive back pressure that setup might generate. Too much back pressure can cause a cylinder or two to go premtaurely. That happened on our Volvo MD7A

[Sailorguy]

I have a small diesel generator that is very sensitive to exhaust system back pressure...so in order to reduce it I eliminated the typical goose neck riser (near the stern exit)and inserted a plastic pvc ball valve between the lift muffler and the transom outlet, the valve is accessible from a cockpit locker. Purchased from Ace hardware, in-expensive and has held up well...Steve

[SkiprJohn]

Aloha Sailorguy,
I was thinking that since my Vetus muffler and gooseneck are made of plastic then why not the ball valve too?
You seem to have tried this with some luck.
My exhaust will exit on the port side. Not installed yet.
Kind regards,
JohnL

[Hiracer]

Originally Posted by Christian Van H

My boat uses a modified wet exhaust system unlike everything just posted

My knowledge in this area is more than a little deficient. What is a modified wet exhaust?

And what is the normal system from which it is to be distinguished?

TIA.

[Christian Van H]

Originally Posted by Hiracer

My knowledge in this area is more than a little deficient. What is a modified wet exhaust?

I cant find a diagram on the 'net, and my manual is down on the boat, but basically there is a SS muffler mounted ABOVE the manifold. Raw water is injected into this muffler and both gases and water exit the bottom and flow "downhill" and out the stern. It's extremely reliable with very low backpressure. Sorry I cant do better right now...

[peterroach]

Hang the boat keys on the shut off valve handle when you turn it off. That way you can't turn on the boat without at least seeing the valve.

I do this with my intake through hull when I turn it off. It has saved me many a times.