Through-hull question
 

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

Through-hull question
 

"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

Through-hull question
 

"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

Through-hull question
 

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

Through-hull question
 

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

Through-hull question
 

"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

Through-hull question
 

"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

Through-hull question
 

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

Through-hull question
 

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

Through-hull question
 

I have all Marlon thru-hulls on my Freedom 40/40 and have never had any
problems. And there are no bonding issues to worry about. Freedom also
states that you don't have to worry about the thru-hulls blowing out in
the case of a lightening strike, but I don't know how real that is.
Just something to ponder.

-- Geoff

Glenn Ashmore wrote in
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 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.