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  #11   Report Post  
 
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Default 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   Report Post  
Steve
 
Posts: n/a
Default 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   Report Post  
Steve
 
Posts: n/a
Default 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   Report Post  
Doug Dotson
 
Posts: n/a
Default 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   Report Post  
Doug Dotson
 
Posts: n/a
Default 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   Report Post  
Jere Lull
 
Posts: n/a
Default 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   Report Post  
Jere Lull
 
Posts: n/a
Default 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   Report Post  
Skip Gundlach
 
Posts: n/a
Default 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   Report Post  
Skip Gundlach
 
Posts: n/a
Default 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   Report Post  
Steve
 
Posts: n/a
Default 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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