I don't know that anyone still makes the traditional in-line tapered
barerel seacocks any more. Wilcox-Critenden made the last that I know
of. Spartan Marine still makes a horozontal barrel but that is about
it. Groco and Conbraco/Apollo make only ball type.

There are several reasons that ball type valves have replaced tapered
plugs. Tapered barrels have to be exactly mated to the valve body.
That means they are expensive to make but that is not the main reason.
First because of the close tolerances, the barrel cannot be replaced.
The whole seacock must be replaced. Second, because of the large
contact area they are much harder to turn and more prone to freezing up.
Third, with use the barrel tends to get wasp waisted and leaks.
Tightning becomes a delicate balance between stopping the leak and
squeezing out the grease which leads to freezing up.

Ball type seacocks use standard parts so they are less expensive to make
and easier to replace parts. The nylon seats accomodate any variation
in tolerance due to wear and are fairly easy to replace.

Keep in mind that I am talking about ball type seacocks. Not ball
valves. Seacocks have bases that bolt to the hull. Ball valves are
fine for use down stream but not screwed to a throughull.

Jere Lull wrote:
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.


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com