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Old 31-10-2011, 10:27   #16
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Re: Exhaust: "Ball Valve"

I have heard of others installing a ball valve at the exhaust outlet to ensure no water entered while running in heavy weather. Switchable by reaching into the lazarette. Indeed, somewhere in the distant past I recall a tale of yacht suffering motor flooding from this cause. I would guess the rubber flap valve would be adequate - hope so cos that is my intention.

I could envisage installing two ball valves on the side outlets if I had a "north sea exhaust" which I could close if the yacht were to lie over on its side while aground.

I can imagine the stern trapped under a pontoon or bridge allowing transom ingress but would be rare. Same rationale as having a valve on every other hull outlet and inlet. My father had a large yacht which was flooded while lying over in shallow water - water flooded in through the sink outlet fast enough to cause major machinery damage.
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Old 31-10-2011, 10:34   #17
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Re: Exhaust: "Ball Valve"

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Originally Posted by Hud3 View Post
Alecadi,

The only thing I can come up with that's "motoring" related is the potential for cooling water to get into the cylinders if you crank a diesel too long without it starting. When starting my engine for the first time after a seasonal layup, I'd always leave the raw water seacock just cracked open a little bit until the engine fired up, then I'd open it all the way.

That's the only way I can think of that seawater could get into an operating diesel.
Thanks for the tip.
Alec
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Old 31-10-2011, 10:35   #18
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Re: Exhaust: "Ball Valve"

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Originally Posted by hugosalt View Post
External exhaust flapper valve very good idea.
Internal in-line flapper valve bad idea...same as one way bilge flapper valve.
Have seen passagemakers with ball valves...but thought bad idea as
would be one more item to worry about if needed motor operating quickly.
Yeap.. makes a lot of sense
Thank you for your advice
Alec
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Old 31-10-2011, 10:38   #19
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Re: Exhaust: Ball Valve

When I read this I thought the OP was talking about a ball in the pipe, like a roll over valve in the fuel tank in cars.
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Old 31-10-2011, 10:47   #20
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Re: Exhaust: Ball Valve

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Originally Posted by Matt sachs View Post
When I read this I thought the OP was talking about a ball in the pipe, like a roll over valve in the fuel tank in cars.
At first I thought it was that effectively but after reading the posts of fellow sailors I understood that that was something totally different.. like a sea cock
Anyway I'll try to have some feed back from people using the flapper type.
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Old 31-10-2011, 11:28   #21
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Re: Exhaust: "Ball Valve"

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Originally Posted by stillbuilding View Post
... I could envisage installing two ball valves on the side outlets if I had a "north sea exhaust" which I could close if the yacht were to lie over on its side while aground ...
See Dave Gerr's "North Sea Exhaust" diagram, which doesn't include seacocks:
TRANSVERSE EXHAUST SYSTEM - Cruisers & Sailing Photo Gallery
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Old 31-10-2011, 14:57   #22
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Re: Exhaust: Ball Valve

G'Day all,

On a previous boat whose exhaust couldn't be looped up high enough for me, I used a rubber plug that I could insert in the exhaust outlet when going to sea. I could reach it hanging over the stern (ouch) and the engine had no problem blowing it back out if I needed to start it up. The plug was hung from a bit of string so that it could be retrieved. A bit cumbersome but it worked!

Cheers,

Jim
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Old 31-10-2011, 14:58   #23
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Re: Exhaust: Ball Valve

Gord, that's close to my system on my steel sailboat: a waterline exhaust outlet on the starboard side. It allows the aft cabin to be free of fumes and long, weird runs. So imagine "half"...just a big hose to the stb. waterline.

However, as I have been bitten before by backpressure, down flooding or what have you, I would like to install a shut off at the exhaust outlet. A flap is going to tear off, being on the side, and it's possible that heeled over enough or sliding down a big 'un could push water back into the system no matter how high (and it's about 30 inches) the top of the exhaust loop is above the engine.

My question is therefore similar to the OP's, but with the refinement that I want to put a solenoid or some sort of contact that means the engine won't fire if that seacock is shut for sailing. Access is good and I can envision easily a small length of threaded rod and a few clamps that could do this job easily without having to get into the engine bay to switch on the engine.
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Old 31-10-2011, 18:10   #24
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Re: Exhaust: Ball Valve

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G'Day all,

On a previous boat whose exhaust couldn't be looped up high enough for me, I used a rubber plug that I could insert in the exhaust outlet when going to sea. I could reach it hanging over the stern (ouch) and the engine had no problem blowing it back out if I needed to start it up. The plug was hung from a bit of string so that it could be retrieved. A bit cumbersome but it worked!

Cheers,

Jim
as always !!
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Old 31-10-2011, 18:34   #25
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Re: Exhaust: Ball Valve

You can find a good article on considerations for wet exhaust here: Good Old Boat - Cool and Quiet and trouble-free article
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Old 31-10-2011, 18:56   #26
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Re: Exhaust: Ball Valve

Here is a picture of the exhaust "Ball valve" on my Westsail, idea is if there was a large folllowing sea the valve could be closed to prevent flooding the motor. The exhaust also has a riser at the motor and the hose goes to a loop well above the ball valve that makes it highly unlikely that any water would finds it way to the motor if the valve was not closed.
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Old 31-10-2011, 19:16   #27
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Not a big expense in a small boat with small diameter exhaust but a bit more costly when one has a 5" diameter exhaust.
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Old 01-11-2011, 07:08   #28
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Re: Exhaust: Ball Valve

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Originally Posted by cburger View Post
Here is a picture of the exhaust "Ball valve" on my Westsail, idea is if there was a large folllowing sea the valve could be closed to prevent flooding the motor. The exhaust also has a riser at the motor and the hose goes to a loop well above the ball valve that makes it highly unlikely that any water would finds it way to the motor if the valve was not closed.
Thank you. Got it: as they said :"a good picture is worth a thousand words.."
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Old 01-11-2011, 07:31   #29
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Re: Exhaust: Ball Valve

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Originally Posted by cburger View Post
Here is a picture of the exhaust "Ball valve" on my Westsail, idea is if there was a large following sea the valve could be closed to prevent flooding the motor. The exhaust also has a riser at the motor and the hose goes to a loop well above the ball valve that makes it highly unlikely that any water would finds it way to the motor if the valve was not closed.
If the riser is high enough to make backflooding “highly unlikely”, then the seacock valve is redundant, unnecessary, and poses the risk of restricting an operating engine (if inadvertently left closed).
I don’t really see the point.
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Old 01-11-2011, 09:51   #30
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Re: Exhaust: Ball Valve

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If the riser is high enough to make backflooding “highly unlikely”, then the seacock valve is redundant, unnecessary, and poses the risk of restricting an operating engine (if inadvertently left closed).
I don’t really see the point.
Gord:
When I was pilot on single engine planes, we were used to redundancy..It was the first principle in security.. belt and suspender
Why not on boats?
Just a question
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