"Steve" wrote in message
...

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..

Steve,
Are your machine screws stainless or other metal? If
stainless, keep an eye out for corrosion under the epoxy.
Stainless doesn't like to be deprived of oxygen, as you
know!

--
JimB
Yacht Rapaz, sadly for sale:

http://homepage.ntlworld.com/jim.bae...cification.htm
jim(dot)baerselman(at)ntlworld(dot)com

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

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..

Steve
s/v Good Intentions

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/

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

"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

"Steve" wrote in message
...

I just wish I had a good online reference to what a proper tapered plug
valve looks like..


OK, here is the best I could do with a quick Google. It is a commercial
TAPERED PLUG VALVE.
http://www.conind.com/pdf/plug%20valve.pdf

It's not a sea cock but it is a tapered plug valve and has straight threads
on the inlet side and standard pipe threads on the outlet side. In this
valve the plug could be removed and the plug lapped/overhauled without
removing the valve from the system.. With a plug in the through hull, it
could be serviced in the water. (I've done this many times) You could never
do this with a ball valve since the ball can not be easily removed and if it
is, there is no way to resurface the ball surface if scored.

Steve
s/v Good Intentions

On Thu, 8 Jan 2004 19:03:52 -0800, "Steve" wrote:


"Steve" wrote in message
...

I just wish I had a good online reference to what a proper tapered plug
valve looks like..


OK, here is the best I could do with a quick Google. It is a commercial
TAPERED PLUG VALVE.
http://www.conind.com/pdf/plug%20valve.pdf

Thanks, Steve...that's interesting...I still like my ball valves,
though, but in some inaccessible places, these could be good.

R.

That's basically it.

Here's the real deal:
http://spartanmarine.com/source/25.htm

Eric

"Steve" wrote in message ...
"Steve" wrote in message
...

I just wish I had a good online reference to what a proper tapered plug
valve looks like..


OK, here is the best I could do with a quick Google. It is a commercial
TAPERED PLUG VALVE.
http://www.conind.com/pdf/plug%20valve.pdf

It's not a sea cock but it is a tapered plug valve and has straight threads
on the inlet side and standard pipe threads on the outlet side. In this
valve the plug could be removed and the plug lapped/overhauled without
removing the valve from the system.. With a plug in the through hull, it
could be serviced in the water. (I've done this many times) You could never
do this with a ball valve since the ball can not be easily removed and if it
is, there is no way to resurface the ball surface if scored.

Steve
s/v Good Intentions

On Thu, 8 Jan 2004 19:03:52 -0800, "Steve" wrote:


"Steve" wrote in message
...

I just wish I had a good online reference to what a proper tapered plug
valve looks like..


OK, here is the best I could do with a quick Google. It is a commercial
TAPERED PLUG VALVE.
http://www.conind.com/pdf/plug%20valve.pdf

Thanks, Steve...that's interesting...I still like my ball valves,
though, but in some inaccessible places, these could be good.

R.