I'll second this (below). If you want the satisfaction of making it
just right, pull the through hulls and put in seacocks. It isn't that
big a job. However, I just stuck a ball valve on top of a through
hull for the convenience (holding tank pump out). Despite all the
theory about the thread mismatch and all the strain coming on just one
or two threads, there is enough give in the metal that, with some pipe
dope, it's solid. The yard that worked on my boat last year has been
doing it for 20 years and never had a problem.

--

Roger Long



"Wayne.B" wrote in message
...
On Sat, 08 Apr 2006 21:42:21 GMT, Gary
wrote:

All of this
is unneccesary. Mine worked fine, (and so have yours) for almost 40
years. Gary Mull was a good designer.

I agree. Install good quality ball valves on top of the existing
thru
hulls, use reinforced hose rated for underwater service, and call it
a
day. I had virtually the same configuration on my old Cal-34. We
replaced the original gate valves with ball valves at the request of
my insurance company and everything has been fine for 20 years
since.

Since there isn't a perfect fit between the straight and taper
threads, I would use a pipe dope that will set up a bit instead of
Teflon tape.

Those backing blocks are very small. Adding the valves will put a lot
more leverage. Be careful not to store anything heavy that could fall
against these through hulls.

--

Roger Long



wrote in message
oups.com...

Thanks for everyone's comments. I took the hose clamps off the
original
piping yesterday and it looks like it's a 1 inch external diameter,
threaded bronze fitting. Perfect. I'll find a bronze (or stainless?)
ball valve to match, drop it in with some teflon tape, and install
some
good new hose. Looks like all I can get in terms of hose clamps
locally
is 304 but I'll keep an eye on them. Freshwater situation so we'll
see
how it goes.

Here's a shot with the current clear plastic drain hose with the
clamps
removed. You can see the threaded connection partially exposed.

http://users.openface.ca/~fox/drain-connection.jpg

Good point about teeing the other drains in - there are two
seat-level
drains, as well as along the gunnel (sp?) so it's six + sink = seven
feeding into the two lines. Could be a problem for the fiberglass -
also an issue with the flexibility (see the PVC comment, thanks
Gary).

I agree that the drains are a bit small but it looks like it's 1
inch
all the way, so to enlarge them at the point would be a more
substantial project, presumably also would involve replacing the
through hulls with larger diameter. Maybe that's a job for next
season.


Thanks again,

-CB

Yeah I've always been very careful down there with the storage. I have
been considering glassing in a bit of 2x4 as a guard around each drain,
in fact.

Is the understanding that all ball valves will have tapered threads and
that the threads in the photo on the fitting appear to be straight
threads?

-CB

wrote:
Yeah I've always been very careful down there with the storage. I have
been considering glassing in a bit of 2x4 as a guard around each drain,
in fact.

Is the understanding that all ball valves will have tapered threads and
that the threads in the photo on the fitting appear to be straight
threads?

-CB

No. There are ball valves with tapered threads and "seacock" ball valves
with stright threads.
krj

Hm ok. So at this point I'm looking for recommendations on combinations
of hardware (which may be difficult as noted above) -

Assuming that's a NPT thread on the photo, I want to put an NPT

- Marelon ball valve? is this inappropriate?
- bronze ball valve that's not the cheapest one out there?

The Groco stainless ball valve at West Marine is all NPS. I assume this
is what i Do Not Want. Their flanged seacock ($$$) is NPT both ends...
do I need a hose barb fitting to screw into the top end to receive the
hose? Not really sure how that part works..

I guess I can go hash this out at my local chandlery. Anyway thanks
again for everyone's pointers on this matter. Cheers,

-CB

Woops s/NPT/NPS/. that's obviously a straight thread sticking up.

-CB

Through hull fittings are always straight thread. Seacocks are always
straight thread. The reason is that there is no way to predict how
thick the planking and backing block will work out to be. You have to
cut the through hull so that the maximum amount is in the seacock with
just a little margin to get everything tight. The flange of the
seacock then keeps it from coming unscrewed.

It would be odd to find a ball valve with a straight thread (I
looked). Even if you could, it wouldn't be a good idea because,
without a flange against the hull to secure to the backing block (even
if only with bedding), there isn't much to keep it from coming
unscrewed. Try twisting hoses onto that set up.

The purpose of tapered threads is to lock tight but there is always
some uncertainty just where they will end up along the axis of the
pipe because of manufacturing tolerances, torque, etc. That's why
they can't be used where a flange is going to stop the motion at some
point.

Putting the straight thread into the tapered thread results in only a
couple of the threads fully engaging. If you put enough strain on it,
those two threads will strip. That's the theory. It's fact that the
straight thread into the taper thread can not develop anywhere near
the design strength of the joint. It's practice that, with the
malleability of bronze, some pipe dope, and the fact that the whole
thing is typically connected to flexible hose instead of more pipe
that people might be stepping on or which is subject to thermals
stress, the joint is strong enough for boat drain purposes. It is
second best and you do need to recognize that protecting it from
impact and stress is much more important than with a proper seacock
that has a flange to mate with the backing block.

Putting a seacock in is pretty quick and easy with a helper. I did
the ball valve thing with my two head connections because nothing is
stored in the area and I was working alone in cold weather that would
have made working with bedding compound difficult. If I was replacing
gate valves in an engine room where someone might step on the through
hull or anywhere else that it was subject to strain, or if it was
connected to pipe instead of hose, I would definitely use proper
flanged seacocks and new through hulls. Why new? You have to pull
them anyway to trim to proper lengths and they don't cost all that
much.



--

Roger Long



wrote in message
ups.com...
Woops s/NPT/NPS/. that's obviously a straight thread sticking up.

-CB

Thanks for your comments, Roger. I was looking at this Marelon ball
valve, does anyone have any experience with these in the context of
below-waterline drain hardware?

http://tinyurl.com/e9xcp

Thanks,

-CB

I wouldn't have any problem with that but a 1" bronze Groco is only
$22.99 from Hamilton Marine here in Portland.

--

Roger Long



wrote in message
oups.com...
Thanks for your comments, Roger. I was looking at this Marelon ball
valve, does anyone have any experience with these in the context of
below-waterline drain hardware?

http://tinyurl.com/e9xcp

Thanks,

-CB

wrote:
Thanks for everyone's comments. I took the hose clamps off the original
piping yesterday and it looks like it's a 1 inch external diameter,
threaded bronze fitting. Perfect. I'll find a bronze (or stainless?)
ball valve to match, drop it in with some teflon tape, and install some
good new hose. Looks like all I can get in terms of hose clamps locally
is 304 but I'll keep an eye on them. Freshwater situation so we'll see
how it goes.

If you use 304 SS hose clamps, try to see if you can at
least get ones with SS screws as well. In my experience, the
most common failure is when the clamping screws rust out.

Doubled 304 SS clamps should be OK, although you should be
willing to renew them once in a while. Not a big expense item.


Here's a shot with the current clear plastic drain hose with the clamps
removed. You can see the threaded connection partially exposed.

http://users.openface.ca/~fox/drain-connection.jpg

Ouch... hose clamped to threaded fitting? No no no. Of
course, it won't be like that when you're done!



I agree that the drains are a bit small but it looks like it's 1 inch
all the way, so to enlarge them at the point would be a more
substantial project, presumably also would involve replacing the
through hulls with larger diameter. Maybe that's a job for next season.


Could also try the aft drain idea, simpler than bigger
thru-hulls and could be made substantially larger.

Still not as good as an open transom though!


Fresh Breezes- Doug King