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#11
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Sea Cocks
Wow. Live and learn. I have no clue what a plug valve is, but I like
the sound of it. Off to Google I go. R. On Thu, 08 Jan 2004 12:44:16 -0500, DSK wrote: Steve wrote: As others have stated, Gate Valve are not suited for marine use and especially for below the waterline. However, IMHO, the plug valve is superior to the ball valve. The plug valve can be taken apart and cleaned or repaired. It seems that they would be cheaper to manufacture as well.. Agreed. Good plug valves are hard to find, though. One of the chief benefits is that you can disassemble them without taking apart the piping, something that can't be done with ball valves. Also, if they happen to freeze up, they are easier to unfreeze. I looked all over for plug valves to replace some seacocks on our boat last spring, and couldn't find any that we could actually get in time. However, at some boatyard session in the not-too-distant future I have to replace (upsize) two seacocks and intend to have plug valves on hand for that job. Fresh Breezes- Doug King |
#12
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Sea Cocks
A proper sea cock, in the strictest sense (was) a tapered plug valve with a
flange on the outboard side and internal threads for the throught hull.. The flange would be bolted though to the outside with a fitted block on the inside. The through hull was just that and provide little or no structural strength the the installation.. Pipe threads and none tapered through hull threads are weak because of the amount of base metal that is removed during the threading process. Today, you will seldom find a true and proper sea cock. What you will find is a through hull with a valve threaded on the end of the inboard end of the threads.. Even this is not a proper installation because the threads in the standard valve will be tapered while the through hull threads are straight.. When tightened up, only the first couple threads will be holding the pressure and providing mechanical strength. There is often the recommendation that you try standing on your through hull valve to ensure that the through hull is still sound.. That may be an indication of strength of the exposed threads, however straight threads into a tapered valve thread really leads to a valve that could easily vibrate or be accidently loosened. Myself, I'm using the Forespar Marelon flanged Seacocks, with Marelon through hulls.. (objective is to have all non-metalic/non-conductive fittings below the waterline) The flange bolts were a problem so I used flat head machine screws and counter sunk the heads and epoxyed over them to prevent contact with the water. I will have to keep an eye on these over time to see if there is any evidence of water intrusion.. -- My opinion and experience. FWIW Steve s/v Good Intentions |
#13
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Sea Cocks
A proper sea cock, in the strictest sense (was) a tapered plug valve with a
flange on the outboard side and internal threads for the throught hull.. The flange would be bolted though to the outside with a fitted block on the inside. The through hull was just that and provide little or no structural strength the the installation.. Pipe threads and none tapered through hull threads are weak because of the amount of base metal that is removed during the threading process. Today, you will seldom find a true and proper sea cock. What you will find is a through hull with a valve threaded on the end of the inboard end of the threads.. Even this is not a proper installation because the threads in the standard valve will be tapered while the through hull threads are straight.. When tightened up, only the first couple threads will be holding the pressure and providing mechanical strength. There is often the recommendation that you try standing on your through hull valve to ensure that the through hull is still sound.. That may be an indication of strength of the exposed threads, however straight threads into a tapered valve thread really leads to a valve that could easily vibrate or be accidently loosened. Myself, I'm using the Forespar Marelon flanged Seacocks, with Marelon through hulls.. (objective is to have all non-metalic/non-conductive fittings below the waterline) The flange bolts were a problem so I used flat head machine screws and counter sunk the heads and epoxyed over them to prevent contact with the water. I will have to keep an eye on these over time to see if there is any evidence of water intrusion.. -- My opinion and experience. FWIW Steve s/v Good Intentions |
#14
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Sea Cocks
GROCO used to make them. Probably still do. They have
a rubber plug. My current boat has ones with bronze plugs, not sure of the brand though. Doug s/v Callista wrote in message ... Wow. Live and learn. I have no clue what a plug valve is, but I like the sound of it. Off to Google I go. R. On Thu, 08 Jan 2004 12:44:16 -0500, DSK wrote: Steve wrote: As others have stated, Gate Valve are not suited for marine use and especially for below the waterline. However, IMHO, the plug valve is superior to the ball valve. The plug valve can be taken apart and cleaned or repaired. It seems that they would be cheaper to manufacture as well.. Agreed. Good plug valves are hard to find, though. One of the chief benefits is that you can disassemble them without taking apart the piping, something that can't be done with ball valves. Also, if they happen to freeze up, they are easier to unfreeze. I looked all over for plug valves to replace some seacocks on our boat last spring, and couldn't find any that we could actually get in time. However, at some boatyard session in the not-too-distant future I have to replace (upsize) two seacocks and intend to have plug valves on hand for that job. Fresh Breezes- Doug King |
#15
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Sea Cocks
GROCO used to make them. Probably still do. They have
a rubber plug. My current boat has ones with bronze plugs, not sure of the brand though. Doug s/v Callista wrote in message ... Wow. Live and learn. I have no clue what a plug valve is, but I like the sound of it. Off to Google I go. R. On Thu, 08 Jan 2004 12:44:16 -0500, DSK wrote: Steve wrote: As others have stated, Gate Valve are not suited for marine use and especially for below the waterline. However, IMHO, the plug valve is superior to the ball valve. The plug valve can be taken apart and cleaned or repaired. It seems that they would be cheaper to manufacture as well.. Agreed. Good plug valves are hard to find, though. One of the chief benefits is that you can disassemble them without taking apart the piping, something that can't be done with ball valves. Also, if they happen to freeze up, they are easier to unfreeze. I looked all over for plug valves to replace some seacocks on our boat last spring, and couldn't find any that we could actually get in time. However, at some boatyard session in the not-too-distant future I have to replace (upsize) two seacocks and intend to have plug valves on hand for that job. Fresh Breezes- Doug King |
#16
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Sea Cocks
In article ,
"John Smith" wrote: Should sea cocks (under the water line) be ball valves or gate valves? Another vote to remove all gate valves immediately. Yours will be old enough that you don't know when they're going to break (or if they've broken already). I'd be SO worried, I'd haul the boat just do do that job. BTW, often it's lots faster to cut old gate valves off than try to unscrew them. A friend's set of railroad socket wrenches and a 6' breaker bar with two beefy guys couldn't unscrew ours. A jig saw and metal cutting blade got rid of it in 15 minutes. Ball valves are the most usual type you find in marine stores. They come with or with flanges. For below the waterline in locations exposed to knocks or stepping on, I prefer the flanged type. Though others say they don't mate properly with through hulls, the ones I've gotten had plenty of threads in contact. [Seemed to take forever to screw them on!] I would prefer proper sea cocks -- the tapered plug type -- but our ball valves have worked well for just about a decade, so I'm not going to worry about it. -- Jere Lull Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD) Xan's Pages: http://members.dca.net/jerelull/X-Main.html Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/ |
#17
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Sea Cocks
In article ,
"John Smith" wrote: Should sea cocks (under the water line) be ball valves or gate valves? Another vote to remove all gate valves immediately. Yours will be old enough that you don't know when they're going to break (or if they've broken already). I'd be SO worried, I'd haul the boat just do do that job. BTW, often it's lots faster to cut old gate valves off than try to unscrew them. A friend's set of railroad socket wrenches and a 6' breaker bar with two beefy guys couldn't unscrew ours. A jig saw and metal cutting blade got rid of it in 15 minutes. Ball valves are the most usual type you find in marine stores. They come with or with flanges. For below the waterline in locations exposed to knocks or stepping on, I prefer the flanged type. Though others say they don't mate properly with through hulls, the ones I've gotten had plenty of threads in contact. [Seemed to take forever to screw them on!] I would prefer proper sea cocks -- the tapered plug type -- but our ball valves have worked well for just about a decade, so I'm not going to worry about it. -- Jere Lull Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD) Xan's Pages: http://members.dca.net/jerelull/X-Main.html Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/ |
#18
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Sea Cocks
I'm a bit confused, apparently, by semantics or my limited exposure...
I hadn't heard of plug valves, so I went looking. What I saw looked about like every ball valve on the insides - except none had easily position-noted lever handles on the outsides. A tapered plug valve led to visions of the kind of valves I used in titration in school - a tapered seat with a matching taper on the handle/valve, and, perhaps, a spring to hold it firmly down? - but that was not the deal. I presume from reading the various chatter on the topic that perhaps it (taper) refers to the threads at the bottom of the valve/thru-hull? In any event, I'm not the least bit sure how they're better than ball valves, as that's what they look like. Those of you familiar with the benefits of the type over a ball, what is their superiority? Thanks. L8R Skip -- "And then again, when you sit at the helm of your little ship on a clear night, and gaze at the countless stars overhead, and realize that you are quite alone on a great, wide sea, it is apt to occur to you that in the general scheme of things you are merely an insignificant speck on the surface of the ocean; and are not nearly so important or as self-sufficient as you thought you were. Which is an exceedingly wholesome thought, and one that may effect a permanent change in your deportment that will be greatly appreciated by your friends."- James S. Pitkin |
#19
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Sea Cocks
I'm a bit confused, apparently, by semantics or my limited exposure...
I hadn't heard of plug valves, so I went looking. What I saw looked about like every ball valve on the insides - except none had easily position-noted lever handles on the outsides. A tapered plug valve led to visions of the kind of valves I used in titration in school - a tapered seat with a matching taper on the handle/valve, and, perhaps, a spring to hold it firmly down? - but that was not the deal. I presume from reading the various chatter on the topic that perhaps it (taper) refers to the threads at the bottom of the valve/thru-hull? In any event, I'm not the least bit sure how they're better than ball valves, as that's what they look like. Those of you familiar with the benefits of the type over a ball, what is their superiority? Thanks. L8R Skip -- "And then again, when you sit at the helm of your little ship on a clear night, and gaze at the countless stars overhead, and realize that you are quite alone on a great, wide sea, it is apt to occur to you that in the general scheme of things you are merely an insignificant speck on the surface of the ocean; and are not nearly so important or as self-sufficient as you thought you were. Which is an exceedingly wholesome thought, and one that may effect a permanent change in your deportment that will be greatly appreciated by your friends."- James S. Pitkin |
#20
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Sea Cocks
"Skip Gundlach" wrote in message ink.net... I'm a bit confused, apparently, by semantics or my limited exposure... I hadn't heard of plug valves, so I went looking. What I saw looked about like every ball valve on the insides - except none had easily position-noted lever handles on the outsides. A tapered plug valve led to visions of the kind of valves I used in titration in school - a tapered seat with a matching taper on the Your visions were correct. A plug valve has a tappered plug, just as you discribe here.. If you are looking as something that resembles a ball valve then your not looking at a true plug valve. I have been boating for 45 yrs and all of my boats until 10 years ago had tapered plug seacocks. (my last boat being a '76 Cheoy Lee Clipper 33) This boat had 'knock off' tapered plug valves. That was the standard and the proper valve or sea cock in boats built up into the '70s. I just wish I had a good online reference to what a proper tapered plug valve looks like.. I'll do some Googling on my own. Steve s/v Good Intentions |
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