I've never known my outdoor faucet to be in sal****er all the time.
Also, the failure of your outdoor faucet will not likely sink your
house.

My boat had gate valves when I bought it. They were common
practice back when my boat was made. No longer. The surveyor
required that I replace them all.

Doug
s/v CAllista

"Allen McCann" wrote in message
...
Is a"gate valve" the same as the outdoor faucet on most homes? If so what
is the problem with them?

Allen

Doug Dotson wrote:

Why not just do it the right way? NPS thruhull to NPS valve.

Doug

"Roger Long" wrote in message
...

Calder and other authorities are dead set against putting NPT ball valves
on NPS through hull fittings as is often done when replacing gate valves.
The geometry of the thread engagement gives me the willies as well
because all the load is on just one or two threads due to the taper.

My boatyard tells me that they do it all the time however as does
everyone else. The gate valves on my 1980 boat haven't broken off yet
either. I just threaded a one half inch ball valve and through hull
together and it doesn't look or feel as bad as the theory.

Except for a couple of above waterline drains, the seacocks I'm going to
put in will be flanged and bolted. I'm just curious though, has anyone
ever heard of a NPT valve on a NPS through hull breaking off or leaking?

--

Roger Long

On Tue, 19 Apr 2005 18:07:35 -0400, Larry Bradley
wrote:

I just went through this operation. I have a 35 year old sailboat that
does not use the proper bolted-through through-hulls, just the kind
with a big nut on them. The have then been glassed in. There were gate
valves on all of them.

This year, having the engine out, I thought I would try replacing a
few that were in formerly "impossible to get a pipe wrench on" places
when the engine was in.

I tried two - the engine water intake and a cockpit drain. I removed
the gate valve, and got ball valves from Home Depot (I sail in fresh
water, have used them before with no problems). These thread onto the
through-hulls quite nicely - way down the thread, not just at the end.
Lots of pipe dope. No way these will come off - there is a lot of
thread.

I've no way of knowing if the ball valves are NPT or NPS - they don't
say - but I would assume NPT, since damn near everything else in the
plumbing department is NPT.

I replace a 1" gate valve and a 1/2" gate valve this way.

Now that I think about it, several years aho I replaced the gate valve
on the head intake with a ball valve, and it works fine.

YMMV

I've done the same thing in the galley, head, and both cockpit drains.
Only the freshwater intake for the engine is a "proper" seacock. The
only thruhull I replaced was the freshwater intake in the head.

All were "big nut" thru-hulls with gate valves. I replaced them with
brass NPT ball valves, which I service yearly and I have double SS
clamps everywhere. No problems whatsoever. If I were in salt water, I
would act differently.

I do not disdain the arguments, but like you, I have confidence that
these buggers are NOT coming off and are much safer than the original
gate valves. Also I have plugs tied to each thru hull, which I don't
see a lot of here on Lake Ontario, even though that is a "standard
precaution" as well.

R.

On Thu, 21 Apr 2005 00:23:30 -0400, rhys wrote:

On Tue, 19 Apr 2005 18:07:35 -0400, Larry Bradley
wrote:

I just went through this operation. I have a 35 year old sailboat that
does not use the proper bolted-through through-hulls, just the kind
with a big nut on them. The have then been glassed in. There were gate
valves on all of them.

This year, having the engine out, I thought I would try replacing a
few that were in formerly "impossible to get a pipe wrench on" places
when the engine was in.

I tried two - the engine water intake and a cockpit drain. I removed
the gate valve, and got ball valves from Home Depot (I sail in fresh
water, have used them before with no problems). These thread onto the
through-hulls quite nicely - way down the thread, not just at the end.
Lots of pipe dope. No way these will come off - there is a lot of
thread.

I've no way of knowing if the ball valves are NPT or NPS - they don't
say - but I would assume NPT, since damn near everything else in the
plumbing department is NPT.

I replace a 1" gate valve and a 1/2" gate valve this way.

Now that I think about it, several years aho I replaced the gate valve
on the head intake with a ball valve, and it works fine.

YMMV

I've done the same thing in the galley, head, and both cockpit drains.
Only the freshwater intake for the engine is a "proper" seacock. The
only thruhull I replaced was the freshwater intake in the head.

All were "big nut" thru-hulls with gate valves. I replaced them with
brass NPT ball valves, which I service yearly and I have double SS
clamps everywhere. No problems whatsoever. If I were in salt water, I
would act differently.

I do not disdain the arguments, but like you, I have confidence that
these buggers are NOT coming off and are much safer than the original
gate valves. Also I have plugs tied to each thru hull, which I don't
see a lot of here on Lake Ontario, even though that is a "standard
precaution" as well.

R.

When I bought my boat, I gritted my teeth and removed every thru-hull,
each had a gate valve. Oddly enough, my pre-purchase surveyor didn't
see a thing wrong with gate valves...but he dinged the boat for not having
PFDs aboard. A boat needs PFDs aboard when it's on the hard?

I've been aboard a number of boats where the owner has the tapered
plugs neatly stored in a locker (he'll remember which one any minute now).
To me..a novice,.. it makes sense to have the proper plug co-located
with the thru-hull. I wonder why so many boat owners don't.
Norm B

All were "big nut" thru-hulls with gate valves. I replaced them with
brass NPT ball valves, which I service yearly and I have double SS
clamps everywhere. No problems whatsoever. If I were in salt water, I
would act differently.


Why? Do boats not sink in fresh water or something

I do not disdain the arguments, but like you, I have confidence that
these buggers are NOT coming off and are much safer than the original
gate valves. Also I have plugs tied to each thru hull, which I don't
see a lot of here on Lake Ontario, even though that is a "standard
precaution" as well.


The issue is less of gate valve vs ball valve, than it is NPT vs flange
and one of corrosion. Nowadays common cheapo hardware store grade valves
are far more corrosion resistant than anything from years ago (except
possibly the super-expensive Monel sea cocks, which I've seen exactly
once in a lifetime).

A sea cock should (in theory) be supported by a flange, not just screwed
onto a protruding pipe. There are lots of ways... including just plain
heeling... that the pipe & valve come under strain. Still, with modern
materials and good attention to detail (btw it is possible to
overtighten NPT connections & split the casting or collapse the pipe
wall) it should be just fine.



engsol wrote:
When I bought my boat, I gritted my teeth and removed every thru-hull,
each had a gate valve. Oddly enough, my pre-purchase surveyor didn't
see a thing wrong with gate valves...but he dinged the boat for not having
PFDs aboard. A boat needs PFDs aboard when it's on the hard?


LOL but he presumed you were going sailing some day!

Issues with gate valves... at one point they were considered acceptable,
every mass-produced boat had them. In the old days, plug valves were
considered preferable... especially if made of Monel.


I've been aboard a number of boats where the owner has the tapered
plugs neatly stored in a locker (he'll remember which one any minute now).
To me..a novice,.. it makes sense to have the proper plug co-located
with the thru-hull. I wonder why so many boat owners don't.

It's just one more thing. Lots of the boats I go on have tapered wooden
plugs tied with yard around the base of the thru hull... a nice
precaution... but frankly I'd have more faith in a plastic baggy & some
duct tape.

How many people have removed seacocks & thru-hulls entirely, and
fiberglassed over the hole?

http://community.webshots.com/photo/...73346002sUSTvu

This is one way to absolutely, positively, guarantee that it won't ever
leak! But you have to be sure that you don't want whatever system it
supplied seawater to. In this case, it was the seawater inlet for the
head which I tied in to the seawater circuit for the A/C... not
satisfactory really. It was a case of connecting too many things to one
valve & strainer, and the A/C pump kept losing it's prime until I
installed a check valve (highly not recommended). But we're installing a
FW flush head this spring.

Fresh Breezes- Doug King

On Thu, 21 Apr 2005 14:26:51 -0400, DSK wrote:

All were "big nut" thru-hulls with gate valves. I replaced them with
brass NPT ball valves, which I service yearly and I have double SS
clamps everywhere. No problems whatsoever. If I were in salt water, I
would act differently.


Why? Do boats not sink in fresh water or something

Sure they do, but sal****er eventually dissolves brass fittings,
meaning they are a no-no in even brackish water.. "Proper" seacocks
are salt-resistant bronze, or these days, Marelon. In fresh water, you
can use brass plumbing ball valves...at about 1/4-1/8 the price of
bronze. The actual thru-hulls are still bronze: it's the cocks screwed
onto them that are brass, with teflon tape and thread sealer between.




The issue is less of gate valve vs ball valve, than it is NPT vs flange
and one of corrosion. Nowadays common cheapo hardware store grade valves
are far more corrosion resistant than anything from years ago (except
possibly the super-expensive Monel sea cocks, which I've seen exactly
once in a lifetime).

A sea cock should (in theory) be supported by a flange, not just screwed
onto a protruding pipe. There are lots of ways... including just plain
heeling... that the pipe & valve come under strain. Still, with modern
materials and good attention to detail (btw it is possible to
overtighten NPT connections & split the casting or collapse the pipe
wall) it should be just fine.

I have been careful with the hoses and whatnot to avoid lateral
forces. I suppose if the engine came loose and slammed into the ball
valve at speed, I'd be in trouble, but that could easily tear a hole
in the actual hull, meaning I have bigger issues.

R.