I don't trust plastic below the waterline. Marelon is
plenty strong but bronze is stronger. I have to install
a few more thru-hulls this spring. I guess I'll have to
do some thinking about it.

Doug
s/v Callista

"Glenn Ashmore" wrote in message
news:vvkDb.4930$JD6.3668@lakeread04...
Not surprising. A proper flanged and bolted bronze seacock cost about 4
times as much as a throughhull and ball valve. I compromised with
flanged and bolted Marelon.

doug dotson wrote:

Hummmm. It seems that many production boat manufacturers
are doing it wrong then. My old C&C didn't have any of the seacocks
through-bolted. On my current boat the seacock has a flange which
does secure the thru-hull, but there are no provision for bolts.

Doug
s/v Callista

"98stratus" wrote in message
...

Wrong...
if you use a proper seacock, throw the nut from the through hull away.

The

seacock should be through bolted, but mose people seem to screw it to
the
backing plate. Which is better than nothing. Also throw away those ball
vales, they are not designed for this task and. Yes you are correct
you
only have 2 or 3 threads seperating you from a sinking!

Pierre

"doug dotson" wrote in message
...

I think you have answered your own question. To the best of
my knowledge ball valves are not acceptable for seacocks.
Not sure why. That may be why thru-hulls and seacocks use
straight threads. So ball valves won't fit. I've never had a seacock
bolted to the hull. Normally the thru-hull is bedded and secured with
the retaining ring and the seacock is just threaded on. Even
though the seacock has a flange that will accept bolts, the flange
has always just floated.

Doug
s/v Callista

"Trent D. Sanders" wrote in message
e.com...

We replaced all the through-hulls on my Islander 29 with new bronze
through-hulls and bronze/stainless ball valves. The threads on the
through-hulls were straight threads, while the threads on the ball
valves were tapered [pipe] threads. As a consequence the ball valves
only tightened down on the through-hulls by about 2 "turns". The
yardman that did the job said that was the "accepted practice" and not
to worry about it.

But,,,, in this month's issue of Good Old Boat's newsletter supplement
there's this,,, "You must use straight threads on both the valve and
through-hull, or tapered on both. Mixing tapered and straight threads
is the worst thing you can do, and sadly it is [or was] common".

So, my question is,,,, does anyone know where to obtain
bronze/stainless ball valves with straight threads? Easier to replace
the ball valves rather than the through-hulls.

I'd use proper seacocks but they require bolting to the hull which
would be difficult with a fiberglass hull.

Thanking you in advance,

Trent Sanders
S/V Cimba
Marina Del Rey
Southern California






--
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

Doug Dotson wrote:

I don't trust plastic below the waterline. Marelon is
plenty strong but bronze is stronger. I have to install
a few more thru-hulls this spring. I guess I'll have to
do some thinking about it.

I had the same worry before I decided so I tried (as my compulsive
engineer personality requires) to analyze the threat. Corrosion is not
a problem. The main threats of marelon vs bronze are breakage because
of the lower ultimate strength and dimensional stability. Dimensional
stability results in sticking so routine exercising the valve and
lubrication are definitely in order. That is a good idea for bronze
also because chrome on bronze balls can flake and jam and stainless
balls can suffer crevasse corrosion between the seals. That leaves the
strength to be tested. I see 3 potential forces acting on a flange
mounted throughhull. The water pressure from outside for which the
flanges are far over designed, the bending force of the hose and
fittings but the fittings are much weaker than the throughuull and
potential impacts. Side impacts would be the big worry.

I tried to visualize what would cause a significant side impact on a
throughhull, probably in a knock down or roll over and came up with a
battery breaking loose, an anchor stowed loose in the bilge. So I found
an old used Forespar 1 1/2" seacock on ebay, mounted it on a piece of
1/4" steel plate and whacked it on the side with a 5 lb sledge. First
blow had no effect. Second blow produced a small crack about 1" long
leading from the valve stem. Third blow broke a bolt flange and
lengthened the crack some but it was still well attached to the
throughhull. I have beaten enough bronze castings to pieces to fit in
my crucible furnace that I don't believe a bronze throughhull would have
held up but a little better.

--
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

"Glenn Ashmore" wrote in message
news:gDuDb.5356$JD6.2598@lakeread04...


Doug Dotson wrote:

I don't trust plastic below the waterline. Marelon is
plenty strong but bronze is stronger. I have to install
a few more thru-hulls this spring. I guess I'll have to
do some thinking about it.

I had the same worry before I decided so I tried (as my compulsive
engineer personality requires) to analyze the threat. Corrosion is not

clip

I tried to visualize what would cause a significant side impact on a
throughhull, probably in a knock down or roll over and came up with a
battery breaking loose, an anchor stowed loose in the bilge. So I found
an old used Forespar 1 1/2" seacock on ebay, mounted it on a piece of
1/4" steel plate and whacked it on the side with a 5 lb sledge. First
blow had no effect. Second blow produced a small crack about 1" long
leading from the valve stem. Third blow broke a bolt flange and
lengthened the crack some but it was still well attached to the
throughhull. I have beaten enough bronze castings to pieces to fit in
my crucible furnace that I don't believe a bronze throughhull would have
held up but a little better.

I thought this was about Marelon - did you do the same thing to one of
those? If so, what was the outcome? I like the concept of Marelon, if only
because it can't rot and ought to move more reliably...

L8R

Skip

--
"Twenty years from now you will be more disappointed by the things you
didn't do than by the ones you did do. So throw off the bowlines. Sail away
from the safe harbor. Catch the trade winds in your sails. Explore. Dream.
Discover." - Mark Twain

The seacock was Marelon. Marelon is a Forespar trade name for glass
filled Dupont Zytel, a sort of super nylon.

Skip Gundlach wrote:

"Glenn Ashmore" wrote in message
news:gDuDb.5356$JD6.2598@lakeread04...


Doug Dotson wrote:


I don't trust plastic below the waterline. Marelon is
plenty strong but bronze is stronger. I have to install
a few more thru-hulls this spring. I guess I'll have to
do some thinking about it.

I had the same worry before I decided so I tried (as my compulsive
engineer personality requires) to analyze the threat. Corrosion is not


clip

I tried to visualize what would cause a significant side impact on a
throughhull, probably in a knock down or roll over and came up with a
battery breaking loose, an anchor stowed loose in the bilge. So I found
an old used Forespar 1 1/2" seacock on ebay, mounted it on a piece of
1/4" steel plate and whacked it on the side with a 5 lb sledge. First
blow had no effect. Second blow produced a small crack about 1" long
leading from the valve stem. Third blow broke a bolt flange and
lengthened the crack some but it was still well attached to the
throughhull. I have beaten enough bronze castings to pieces to fit in
my crucible furnace that I don't believe a bronze throughhull would have
held up but a little better.


I thought this was about Marelon - did you do the same thing to one of
those? If so, what was the outcome? I like the concept of Marelon, if only
because it can't rot and ought to move more reliably...

L8R

Skip


--
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

"Glenn Ashmore" wrote in message
news:1ewDb.5363$JD6.3416@lakeread04...
The seacock was Marelon. Marelon is a Forespar trade name for glass
filled Dupont Zytel, a sort of super nylon.

Ah - very good. You're saying the metal failed while the plastic didn't?

That's very reassuring. Confirms my expectations that such upgrade is
worthwhile.

L8R

Skip
--
"Twenty years from now you will be more disappointed by the things you
didn't do than by the ones you did do. So throw off the bowlines. Sail away
from the safe harbor. Catch the trade winds in your sails. Explore. Dream.
Discover." - Mark Twain

Skip Gundlach wrote:


Ah - very good. You're saying the metal failed while the plastic didn't?

That's very reassuring. Confirms my expectations that such upgrade is
worthwhile.


I didn't go so far as to say that and I am not about to bash up a $150
bronze seacock to find out. :-) My testing was also more subjective
than a true a scientific examination. It is just that the 1 1/2" marelon
seacock is strong enough to stand up to any potential impact hazzard
that I can think of. The story may be different with a 3/4" seacock but
it will still be close enough to the strength of bronze to be acceptable
to me.

--
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

Glenn,

I was just browsing through the WM catalog. A 3/4" Marelon
thruhull is $11.49, bronze is $12.99. A 3/4" Maralon seacock is $37.99,
bronze is $36.99. I don't see the
price of bronze as a major deal. That is unless the
Apollo seacock has some sort of bad rep. The Groco
seacocks are about double the price. Not sure where
the 4X price you suggested comes from? Looks to me
like break even or at the most 2X. I do like the Marelon
inasmuch as electrical problems are eliminated though.

Doug
s/v Callista

"Glenn Ashmore" wrote in message
news:3GDDb.5377$JD6.2851@lakeread04...


Skip Gundlach wrote:


Ah - very good. You're saying the metal failed while the plastic
didn't?

That's very reassuring. Confirms my expectations that such upgrade is
worthwhile.


I didn't go so far as to say that and I am not about to bash up a $150
bronze seacock to find out. :-) My testing was also more subjective
than a true a scientific examination. It is just that the 1 1/2" marelon
seacock is strong enough to stand up to any potential impact hazzard
that I can think of. The story may be different with a 3/4" seacock but
it will still be close enough to the strength of bronze to be acceptable
to me.

--
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

Glenn,

I was just browsing through the WM catalog. A 3/4" Marelon
thruhull is $11.49, bronze is $12.99. A 3/4" Maralon seacock is $37.99,
bronze is $36.99. I don't see the
price of bronze as a major deal. That is unless the
Apollo seacock has some sort of bad rep. The Groco
seacocks are about double the price. Not sure where
the 4X price you suggested comes from? Looks to me
like break even or at the most 2X. I do like the Marelon
inasmuch as electrical problems are eliminated though.

Doug
s/v Callista

"Glenn Ashmore" wrote in message
news:3GDDb.5377$JD6.2851@lakeread04...


Skip Gundlach wrote:


Ah - very good. You're saying the metal failed while the plastic
didn't?

That's very reassuring. Confirms my expectations that such upgrade is
worthwhile.


I didn't go so far as to say that and I am not about to bash up a $150
bronze seacock to find out. :-) My testing was also more subjective
than a true a scientific examination. It is just that the 1 1/2" marelon
seacock is strong enough to stand up to any potential impact hazzard
that I can think of. The story may be different with a 3/4" seacock but
it will still be close enough to the strength of bronze to be acceptable
to me.

--
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

Skip Gundlach wrote:


Ah - very good. You're saying the metal failed while the plastic didn't?

That's very reassuring. Confirms my expectations that such upgrade is
worthwhile.


I didn't go so far as to say that and I am not about to bash up a $150
bronze seacock to find out. :-) My testing was also more subjective
than a true a scientific examination. It is just that the 1 1/2" marelon
seacock is strong enough to stand up to any potential impact hazzard
that I can think of. The story may be different with a 3/4" seacock but
it will still be close enough to the strength of bronze to be acceptable
to me.

--
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

"Glenn Ashmore" wrote in message
news:1ewDb.5363$JD6.3416@lakeread04...
The seacock was Marelon. Marelon is a Forespar trade name for glass
filled Dupont Zytel, a sort of super nylon.

Ah - very good. You're saying the metal failed while the plastic didn't?

That's very reassuring. Confirms my expectations that such upgrade is
worthwhile.

L8R

Skip
--
"Twenty years from now you will be more disappointed by the things you
didn't do than by the ones you did do. So throw off the bowlines. Sail away
from the safe harbor. Catch the trade winds in your sails. Explore. Dream.
Discover." - Mark Twain