A couple of weeks ago I posted a plea for advice re removing
old thru-hulls. The boat, as you may recall, is a Yankee 30,
built in 1974.

As an update, and in hope it might help another new sailor, I'm posting
my experience with removing all 7 thru-hulls.

The difficulty seemed to fall into two catagories....one: the valve
could be removed from the thru-hull, and two: it couldn't

In the easiest case (one), a big pipe wrench was sufficient to
remove really old gate valves. The spinning off the thru-hull
nut was easy. A tap with a hammer caused the thru-hull to pop right
out.. In one case where that didn't work, using another thru-hull
nut as a jam nut, then applying a wrench to both worked. If the
sealant is 3M 5200 you'll have to use a propane torch to heat
the thru-hull while keeping steady pressure on the thru-hull
with a wrench.

The harder case (two) was where the valve resisted all attempts
at breaking it free. In that case the thru-hull nut was backed out
as far as possible, then the thru-hull was twisted with a pipe wrench
(below the nut) until it turned. The thru-hull was pulled out from the
hull as far as possible, (from the outside of the hull), and a hacksaw
was used to cut through the thru-hull.

What did I learn? Old sealant is very weak. Boat yard advice is not to be
trusted. Old thru-hulls are not made any more, so get the
West System brochure...you'll need it to learn how to plug old
thru-hull holes and drill new ones.

Bear in mind I'd planned on replacing all thru-hulls...if you want to
save the old ones your milage may vary.

Regards, Norm B

PS: Working on a boat in 35 degree F weather, including wind,
is NOT a lot of fun. But summer will come...right?

Old thru-hulls are not made any more, so get the
West System brochure...you'll need it to learn how to plug old
thru-hull holes and drill new ones.


Yikes! Please tell us more about this. These things are supposed to
be NPT and NPS standard. I see fittings in the store that look just
like I've been seeing for 40 years.

What changed and when?

How could they have changed so much that you can't put a new one back
in the same hole, even if the size is slightly different?

--

Roger Long

They haven't. I replaced all mine on an '85 Krogen and the new ones fit
exactly.

I did replace a bunch of those old rubber plug type seacocks, and readily
sold them on E-bay to folks who needed them for replacement parts!

We ended up using an angle grinder to just grind off the exterior mushroom
part of some of the thru-hull fittings to get them out. If you have a cored
hull, that is a good time to make sure the coring has been routed out for an
inch or so and filled with epoxy. If not, do it now. As the original poster
stated, old bedding compound can (will) fail eventually. If you have one
with 5200, it obviously was installed relatively recently. They do have
something called anti-bond 2000 that will soften that stuff up as well.

--


Keith
__
"I'll always be Number 1 to myself."
-Moses Malone
"Roger Long" wrote in message
...
Old thru-hulls are not made any more, so get the
West System brochure...you'll need it to learn how to plug old
thru-hull holes and drill new ones.


Yikes! Please tell us more about this. These things are supposed to be
NPT and NPS standard. I see fittings in the store that look just like
I've been seeing for 40 years.

What changed and when?

How could they have changed so much that you can't put a new one back in
the same hole, even if the size is slightly different?

--

Roger Long

On Sun, 02 Jan 2005 18:24:26 -0800, engsol
wrote:

A couple of weeks ago I posted a plea for advice re removing
old thru-hulls. The boat, as you may recall, is a Yankee 30,
built in 1974.

As an update, and in hope it might help another new sailor, I'm posting
my experience with removing all 7 thru-hulls.

The difficulty seemed to fall into two catagories....one: the valve
could be removed from the thru-hull, and two: it couldn't


My boat is a 1979 Formosa 46. I discovered a retrofit to one
throughhull in the galley had been done with a piece of black iron
pipe. (Soft iron used for natural gas in houses on land!) This was not
original and the rest of the original seacocks and throughhulls are in
good condition.
This one had soft iron welded to the bronze seacock by corrosion. I
hauled the boat before even messing with it. The black iron broke away
with not much pressure from a pipe wrench. I decided to replace the
seacock.
In the end, I used a sawsall (reciprocating saw) to cut the
seacock's retaining bolts. Somehow I managed to get a wrench into the
cramped space to remove the seacock from the throughhull. Once the
seacock was removed, I used a throughhull wrench (Fits inside the
throughhull from the outside of the boat.) to back out the old
throughhull. For being over 20 years in salt water, both the
throughhull and the seacock were in very good condition. Only the
retrofit using the wrong material had caused the problem. When
cleaned, I could not tell them from the new replacements. I did not
need to replace the throughhull but I did.
The hull is not cored. It is solid glass. I bedded and installed a
new throughhull that fit the threads in the old hole. I bedded and
installed a new seacock.

On Mon, 03 Jan 2005 11:53:24 GMT, "Roger Long" wrote:

Old thru-hulls are not made any more, so get the
West System brochure...you'll need it to learn how to plug old
thru-hull holes and drill new ones.


Yikes! Please tell us more about this. These things are supposed to
be NPT and NPS standard. I see fittings in the store that look just
like I've been seeing for 40 years.

What changed and when?

How could they have changed so much that you can't put a new one back
in the same hole, even if the size is slightly different?

Good question(s). I should have been more specific. All the thru-hulls on
my boat were flush fiting. A few had a non-standard flange or bevel. They
are 45 degrees, but the depth and diameter are non-standard. Believe me,
I looked at every nautical web site and boat store catalog I could find to no
avail. The mushroom style would be no problem of course.

One more point....a 1 1/2 inch "pipe" on a thru-hull is indeed 1 1/2 inches, but that's the ID.
The wall thickness is the "schedule", and I noticed that the old thru-hulls have
a greater wall thickness, but not so much as the proclude screwing on a modern
seacock.

Regards, Norm B

"engsol" wrote in message
...
On Mon, 03 Jan 2005 11:53:24 GMT, "Roger Long"
wrote:
bit snipped for brevity
One more point....a 1 1/2 inch "pipe" on a thru-hull is indeed 1 1/2
inches, but that's the ID.
The wall thickness is the "schedule", and I noticed that the old
thru-hulls have
a greater wall thickness, but not so much as the proclude screwing on a
modern
seacock.

Regards, Norm B

Just to explain this further to prevent any misunderstanding:

While it is true pipe is measured by it's inside diameter, the size stated
is a nominal size. The outside diameter of a pipe does not change as the
pipe's schedule changes. The actual inside diameter does. For example a 1
1/2 inch pipe has an outside diameter of 1.90 inches weather it is schedule
40 or 80. The inside diameter does vary with schedule 40 1 1/2" pipe having
an ID (inside diameter) of 1.61 inches and schedule 80 1 1/2" pipe an ID of
1.50 inches.

This constant outside diameter allows plumbers to use one set of cutters and
the same setup to cut threads onto the outside of any schedule pipe of the
same nominal dimension. And any threaded pipe of a certain nominal size (of
any schedule) will thread into any fitting of the same size (assuming they
both have tapered (NPT) threads or both have straight (NPS) threads). Clear
as mud?

For further info go to http://www.mts.net/~william5/library/pipe.htm and
scroll down to the QUICK REFERENCE CHART.

Happy New Year all!
--
Ken Heaton & Anne Tobin
Cape Breton Island, Canada
kenheaton AT ess wye dee DOT eastlink DOT ca