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Old 01-11-2011, 10:07   #31
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Re: Exhaust: Ball Valve

Redundancy is good; but, in this case, the valves brings itís own offsetting disadvantages.
It requires absolutely reliable operation, and adds complexity & cost.
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Old 01-11-2011, 10:12   #32
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Re: Exhaust: Ball Valve

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Redundancy is good; but, in this case, the valves brings itís own offsetting disadvantages.
It requires absolutely reliable operation, and adds complexity & cost.
I agree with GordMay. The better option is an exhaust system that's bombproof, rather than jury-rigging a fix. It's the unexpected ferry wake that poops you that a ball-valve system won't solve.
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Old 01-11-2011, 10:14   #33
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Consider a Vetus waterlock near the exhaust outlet on inside flapper on outside
Double protection
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Old 01-11-2011, 10:51   #34
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Re: Exhaust: Ball Valve

When I bought my 1979 IOR it had a 3" ball valve (seacock) in the exhaust, which was frozen up. Never the less I removed it and installed a proper riser in the exhaust. I took the seacock apart and found the the chrome plating on the ball had flaked off around the edges, seizing it up. I installed a rebuild kit with the new plastic ball and sold the valve.

Now with my new Yanmar I run duel exhausts, port and stbd, which are interconnected amidship after a riser. I have to get hit on the quarter to get water in, and then it just passes right thru.

But no! No ball valve! Put in a proper riser!!!

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Old 01-11-2011, 11:08   #35
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Re: Exhaust: Ball Valve

With the engine running, there is ZERO chance of water backing up the exhaust. When I was in the assistance towing business we used to valve our exhaust on the gasoline engined boats, but it was strictly to cut in and out the mufflers.

The flappers work fine for stopping the ingress of the errant wave astern with the engine off, and the ONLY situation I could see a ball valve on the exhaust would be if the through-hull was located at or below the waterline, and then only operated in case of a hose failure as one would with any other sea-cock.
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Old 01-11-2011, 13:58   #36
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Re: Exhaust: Ball Valve

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Originally Posted by capngeo View Post
With the engine running, there is ZERO chance of water backing up the exhaust. When I was in the assistance towing business we used to valve our exhaust on the gasoline engined boats, but it was strictly to cut in and out the mufflers.

The flappers work fine for stopping the ingress of the errant wave astern with the engine off, and the ONLY situation I could see a ball valve on the exhaust would be if the through-hull was located at or below the waterline, and then only operated in case of a hose failure as one would with any other sea-cock.
I will put a flapper, definitely: simple and cheap.
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Old 01-11-2011, 15:46   #37
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Re: Exhaust: Ball Valve

I think a surveyor would flag any kind of valve in the exhaust line that could be left closed. Seems like a really bad idea to me. Loop the exhaust and add a flapper if you are very nervous.
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Old 01-11-2011, 17:02   #38
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Re: Exhaust: Ball Valve

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The flappers work fine for stopping the ingress of the errant wave astern with the engine off, and the ONLY situation I could see a ball valve on the exhaust would be if the through-hull was located at or below the waterline, and then only operated in case of a hose failure as one would with any other sea-cock.
Flappers don't work on the sides of boats, where my exhaust is just above the waterline, and although there is a riser there, it's not super high. Water could conceivably back into the exhaust under sail, and a slug of it could go down the exhaust should we be squatting a bit when tacking.

Short of rerouting to the stern, which I don't wish to do, or short of installing a dry or jacketed exhaust up to the top of the pilothouse (also problematic), the seacock with a sensor idea seems logical to me as the alternative isn't good.

And of course, while the engine is on, the boat could be heeled a fair bit...exhaust pressure will blast out regardless.
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Old 01-11-2011, 17:49   #39
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Re: Exhaust: Ball Valve

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I think a surveyor would flag any kind of valve in the exhaust line that could be left closed. Seems like a really bad idea to me. Loop the exhaust and add a flapper if you are very nervous.
Friend's Cal 34 I sailed on for 20 years has a valve, the Cal 40 I bought has a valve. Surveys on both boats never said anything about it.

A single errant wake isn't going to cause a problem. It's not that there isn't some kind of riser, it's that it was inadequate. I've used the valve on the Cal 34 twice, once on the Straits of Georgia pushing the boat hard enough that the waterline on the transom was 3/4ths the way up to the top most of the time and once on the way to Hawaii.

I don't have a problem with making things easier, but I never had a problem with remembering the valve on the exhaust or to switch the 1/2/both switch appropriately, managed to use the reel halyard winch safely all those years, didn't blow myself up with the Atomic 4 gas engine, or whatever thing you're supposed to do. Doesn't matter how automatic or idiot proof you try to make things, if you don't learn and follow the safety procedures you'll find something to damage or hurt yourself with. Logical conclusion is to sail your virtual boat from your computer at home.

If you've got the space and money to do it the new "right way" do it. Otherwise don't get too bent.

John
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Old 01-11-2011, 17:53   #40
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Re: Exhaust: Ball Valve

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Originally Posted by S/V Alchemy View Post
Flappers don't work on the sides of boats, where my exhaust is just above the waterline, and although there is a riser there, it's not super high.
Likewise a following wave is unlikely to push into an athwart ships exhaust.
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Old 01-11-2011, 18:02   #41
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Re: Exhaust: Ball Valve

I have a gate valve fitted to Bluestocking, readily accessable from my lazarette hatch, from the helm.
Older boats like John's Cal, and my boat, have much lower free board aft, than new high sided hulls. We cant always have that much of a riser to underside of deck before the exhaust exit run.
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Old 01-11-2011, 18:10   #42
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Re: Exhaust: Ball Valve

Vetus LSG-series waterlocks incorporate an internal flapper valve. Some exhaust thruhulls face downward and gravity will tend to keep an external flapper open.
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Old 01-11-2011, 21:22   #43
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Re: Exhaust: Ball Valve

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Likewise a following wave is unlikely to push into an athwart ships exhaust.
True indeed, but I am more concerned with the constant "pumping" action of dipping the starboard exhaust aperature below the WL when I'm sailing on port side.

I realize my concerns are essentially minority ones.
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Old 01-11-2011, 21:25   #44
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Re: Exhaust: Ball Valve

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Vetus LSG-series waterlocks incorporate an internal flapper valve. Some exhaust thruhulls face downward and gravity will tend to keep an external flapper open.
I am looking at Vetus gear to replace my SS waterlift for this very reason. I swapped a Vetus waterlock for a faulty and internally corroded Onan waterlift on my sloop (a typical pinched end '70s racer where it's hard to put in an adequate riser at the stern), and have had zero issues since then.

I like the Vetus gear, except for the price. Some one who actually sails appears to have had a hand in the process.
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Old 01-11-2011, 23:47   #45
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Re: Exhaust: Ball Valve

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Originally Posted by delmarrey View Post
When I bought my 1979 IOR it had a 3" ball valve (seacock) in the exhaust, which was frozen up. Never the less I removed it and installed a proper riser in the exhaust. I took the seacock apart and found the the chrome plating on the ball had flaked off around the edges, seizing it up. I installed a rebuild kit with the new plastic ball and sold the valve.

Now with my new Yanmar I run duel exhausts, port and stbd, which are interconnected amidship after a riser. I have to get hit on the quarter to get water in, and then it just passes right thru.

But no! No ball valve! Put in a proper riser!!!

Well I have enough height for a good riser so I can go with that approach OK. I could see that some boats with lower profile could not manage this and might be better with a ball valve.

At the risk of pinching the thread, Del can I ask if the exhaust fumes are a problem with your North Sea arrangement? Your arrangement is what I had planned but even Gerr has mentioned that some owners had had a problem with this exhaust. Just wondering.
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