Seacock/Gate Valves
 

I need to replace some gate valves in our boat and I was looking at
Apollo Ball valves. They say that they will work with thru-the-hulls.
Since thru-the-hulls have straight pipe threads and the ball valves
have tapered pipe threads I don't see how this is possible. Am I
missing something? I know that seacocks have both straight and tapered
threads but a seacock would probably be overkill in this case.

--

Seacock/Gate Valves
 

On May 10, 7:55?am, "James" wrote:
I need to replace some gate valves in our boat and I was looking at
Apollo Ball valves. They say that they will work with thru-the-hulls.


Who is "they"?



Since thru-the-hulls have straight pipe threads and the ball valves
have tapered pipe threads I don't see how this is possible. Am I
missing something?

No, you're going to need to fit something with a compatibel thread.




?I know that seacocks have both straight and tapered
threads but a seacock would probably be overkill in this case.

--

Seacock/Gate Valves
 

James wrote:
I need to replace some gate valves in our boat and I was looking at
Apollo Ball valves. They say that they will work with thru-the-hulls.
Since thru-the-hulls have straight pipe threads and the ball valves
have tapered pipe threads I don't see how this is possible. Am I
missing something? I know that seacocks have both straight and tapered
threads but a seacock would probably be overkill in this case.

There are ball valves that have tapered threads and seacock ball valves
that have straight threads. Apollo and Groco seacocks have NTP (tapered)
top thread and the bottom thread is NPS (straight).

Seacock/Gate Valves
 

"Dave" wrote in message
...
On Thu, 10 May 2007 14:55:37 GMT, "James"
said:

Since thru-the-hulls have straight pipe threads and the ball valves
have tapered pipe threads I don't see how this is possible. Am I
missing something?

Coupla things.

West has some ball valves that will fit right onto the straight threads of
the thru-hull.

However for purists, that setup will run into the objection that the
thru-hull may break as the result of galvanic corrosion when you try to
close the ball valve. Current standards call for a flanged connection.

(Not being that much of a purist, I replaced my gate valves this season
with
ball valves that screw onto the existing thru-hulls. The existing
thru-hull
has held up for 25 years, so I'm not too concerned about it.)

One point, Dave: All through-hulls have a limited lifespan. Essie also
has/had threaded through-hulls onto which seacocks are screwed, but I'm in
the process of eliminating them. In a salt environment, Essie's
through-hulls lasted 40 years. She is now in fresh water, and they still
look and feel solid, but I do not consider that to be a permanent state.

So far I have completely eliminated three of these through-hulls (head
compartment), glassing them out and converting to a porta-potti setup, with
the head sink discharge now being pumped out well above heeled waterline.
Eventually I will eliminate EVERY below-water through-hull that I can.
Ideally, I will have only two: seawater intake for the engine, seawater
intake for the galley sink. But it's an unknown at this time whether or not
I can get my cockpit drains to discharge above waterline.

Seacock/Gate Valves
 

On Thu, 10 May 2007 12:14:32 -0400, krj
wrote:

Apollo and Groco seacocks have NTP (tapered)
top thread and the bottom thread is NPS (straight).

And you can probably bet that at least the Grocos are made with the
right type of bronze, not true with the hardware store variety which
is actuall brass (copper and zinc) vs naval bronze which is primarily
copper and tin. The issue with brass is that the zinc will disappear
over time due to electrolytic action.

Seacock/Gate Valves
 

This is one of those things...

The theoretical reasons for not putting a tapered thread ball valve on a
straight thread through hull are absolute and irrefutable. All the strain
is on just one or two threads. The stress is nearly infinite. The
electrical connections is through a very small amount of metal. It will
sink your boat. No question.

The practical experience and track record of doing this is also absolute and
irrefutable. It's been done for years. I've never heard of a boat sinking
because of it. The just retired yard guy I talked it over with a couple
years ago had been doing it for over 20 years without a problem.

A proper seacock is always better but I have a ball valve threaded onto an
old through hull in my boat. The through hull was rock solid and it was in
a place where nothing heavy could fall against it. The threads just deform
a small amount and pipe sealant does the rest. I would use a stick type
compound that will harden in this case instead of Teflon tape.

--
Roger Long

Seacock/Gate Valves
 

On May 10, 2:57 pm, "Roger Long" wrote:
This is one of those things...

The theoretical reasons for not putting a tapered thread ball valve on a
straight thread through hull are absolute and irrefutable. All the strain
is on just one or two threads. The stress is nearly infinite. The
electrical connections is through a very small amount of metal. It will
sink your boat. No question.

Roger Long


I've seen just that problem on an aluminum boat with bronze seacocks.
The surface contact is so small the electrolysis cuts thru the through
hull threads like a laser, they can just fall off. Was able to break
them all off by hand right before a USCG inspection.

Joe

Seacock/Gate Valves
 

"Joe" wrote

I've seen just that problem on an aluminum boat with bronze seacocks.
The surface contact is so small the electrolysis cuts thru the through
hull threads like a laser, they can just fall off. Was able to break
them all off by hand right before a USCG inspection.

Yikes! I don't care how you do it. If bronze touches aluminum in salt
water, something very bad is going to happen very quickly. Those through
hulls would have failed even if properly threaded.

--
Roger Long

Seacock/Gate Valves
 

"Roger Long" wrote in message
...

"Joe" wrote

I've seen just that problem on an aluminum boat with bronze seacocks.
The surface contact is so small the electrolysis cuts thru the through
hull threads like a laser, they can just fall off. Was able to break
them all off by hand right before a USCG inspection.

Yikes! I don't care how you do it. If bronze touches aluminum in salt
water, something very bad is going to happen very quickly. Those through
hulls would have failed even if properly threaded.

--
Roger Long


Ya, delrin/marlon or other plastic is pretty much mandatory on aluminum.

Seacock/Gate Valves
 

On 2007-05-10 10:55:37 -0400, "James" said:

I need to replace some gate valves in our boat and I was looking at
Apollo Ball valves. They say that they will work with thru-the-hulls.
Since thru-the-hulls have straight pipe threads and the ball valves
have tapered pipe threads I don't see how this is possible. Am I
missing something? I know that seacocks have both straight and tapered
threads but a seacock would probably be overkill in this case.

When I replaced ours, the thru-hulls were relatively cheap and I don't
lose any sleep at all.

At a bare minimum, though, re-caulk them.

Oh, and I forgot to mark the one about hard sealant: Please don't as
the next owner (or you) might want to take them apart to service them.

--
Jere Lull
Tanzer 28 #4 out of Tolchester, MD
Xan's new pages: http://web.mac.com/jerelull/iWeb/Xan/
Our BVI pages: http://homepage.mac.com/jerelull/BVI/