Bronze Screws versus Stainless steel??
rlal...@hotmail.com
My question is three-fold:
Is there a difference between "silcon bronze" and just "bronze" screws?
Is bronze better than stainless?? (They certainly are cheaper)
What, if any downfall is there in using bronze screws (They don't rust, but
do they hold well??)
Thanks in advance for your answers.
PS: Have started building a Stevenson Project - Weekender and having a great
time!!!!!
Ron
-----== Posted via Deja News, The Leader in Internet Discussion ==-----
http://www.dejanews.com/ Now offering spam-free web-based newsreading
Pat Ford
On Sat, 18 Apr 1998 23:00:31 -0600, rlal...@hotmail.com wrote:
>My question is three-fold:
>Is there a difference between "silcon bronze" and just "bronze" screws?
>Is bronze better than stainless?? (They certainly are cheaper)
>What, if any downfall is there in using bronze screws (They don't rust, but
>do they hold well??)
>Thanks in advance for your answers.
>PS: Have started building a Stevenson Project - Weekender and having a great
Reader's Digest version:
High quality boatbuilders will use bronze. Certainly stainless should
not be used in any application where the fastener will be in an
oxygen deprived area like underwater hull fastening.
Stainless fasteners will undergo a degradation called cervice
corrosion if used in this situation.
It is not uncommon for fasteners to be used indiscriminately, but
this is not good practice.
macnaughton.com
Yes there is a difference between bronze and silicon bronze. Some bronzes
may have considerable zinc in them which can produce failure through
"dezincification". Silicon bronze especially the Everdur grade is much
longer lived through allowing little zinc contamination.
Stainless should not be used to fasten wood parts together. Generally there
is a very strong possibility of crevice corrosion and other problems. I have
seen bolts 1/2" in diameter eaten completely through along a nice neat line
where two pieces of wood were joined.
Tom MacNaughton
http://www.macnaughtongroup.com
rlal...@hotmail.com wrote in message <6hbssu$io3$1...@nnrp1.dejanews.com>...
>My question is three-fold:
>Is there a difference between "silcon bronze" and just "bronze" screws?
>Is bronze better than stainless?? (They certainly are cheaper)
>What, if any downfall is there in using bronze screws (They don't rust, but
>do they hold well??)
>Thanks in advance for your answers.
>PS: Have started building a Stevenson Project - Weekender and having a
great
Norman Hirsch
Better? Are you talking about strength or corrosion resistance?
It depends on alot. The word bronze is somewhat confusing as was
originally reserved to be an alloy of copper and tin and now all kinds
of copper based alloys are referred to as being "bronze" some of which
have no tin at all. Silicon bronze is copper and a small amount
(approx 3%) of silicon. Stainless steel is also confusing depending on
the type and whether it is in active or passive mode. I wouldn't use
stainless steel for anything below the water line. Stainless steel
really needs to "breath" believe it or not.
On Sat, 18 Apr 1998 23:00:31 -0600, rlal...@hotmail.com wrote:
>My question is three-fold:
>Is there a difference between "silcon bronze" and just "bronze" screws?
>Is bronze better than stainless?? (They certainly are cheaper)
>What, if any downfall is there in using bronze screws (They don't rust, but
>do they hold well??)
>Thanks in advance for your answers.
>PS: Have started building a Stevenson Project - Weekender and having a great
>time!!!!!
>
>Ron
>
>-----== Posted via Deja News, The Leader in Internet Discussion ==-----
>http://www.dejanews.com/ Now offering spam-free web-based newsreading
--
Best regards,
Norman Hirsch Phone: 212-304-9660
NH&A Fax: 212-304-9759
577 Isham St. # 2-B E-mail: NOSPAM...@nha.com
New York, NY 10034 USA URL: http://www.nha.com
Thurston
Generally, stainless is stronger and cheaper (use monel or 316 grade or
better)...silicon bronze is different than bronze, it is very strong and
more expensive than stainless. However, bronzes are subject to more galvanic
action than quality stainless fasteners.
Pat Ford
On Mon, 20 Apr 1998 06:07:52 GMT, djf...@pipeline.com wrote:
>Hummm, Monel cheap???
>And the last time I looked it was not a Stainless Steel.
Yes, it's a wonderful fastening material. It was used in the interwar
era for boats built of very high quality. Isn't a nickel alloy?
Classic Boatworks of Maine
Silicon Bronze is far superior to Stainless in marine applications.
Stainless steel has its uses and is quite good as long as you do not mix it
with other metals. Good grade stainless (302L or 316L) must be used for
marine applications.
Materials that have de-zinc ifcation are usually considered brass. Bronze
contains tin which chemically ties up the zinc so it doesnot de-zincify.
The material we call silicon bronze is copper with silicon added to it and
is the best grade.
--
Good Luck and Fair Seas
Marshall and Jo Duhaime,Jr.
Classic Boatworks of Maine - We build and restore classic wood boats.
http://www.nemaine.com/classicboatworks
rlal...@hotmail.com wrote in article <6hbssu$io3$1...@nnrp1.dejanews.com>...
JKlopman
302 is not used in marine applications. 304 is, yet would be considered
marginal in immersion service. there are sore high qualitygrades of "super
austenitic" stainless that would be great for our industry, but the
availability for fasteners is not good. Tin does not "tie up" zinc. One common
bronze alloy containing zinc is manganese bronze (26% Zn). It definitely will
suffer selective corrosion. This alloy also has problems now and again with
poorly mixed inclusions of iron (added for strength).
One thing I've noted with sil brz. screws has nothing to do with the alloy -
but the manufacturing. haven't you seen batches with thin threads? Jesus, I
swear you could flick the threads off some right out of the box. How do you
think they will hold up?
Jonathan Klopman
Marine Surveyor
Classic Boatworks of Maine
Sorry about the 302 it was supposed to be 304.
What would you recommend for usage in wood boats? We do a lot of
restoration and reproduction building. The cost of using super materials
(incanels, monels) is prohibitive except in extremely special cases. We do
use some galvanized iron in conjuction with vessels that have previously
been fastened with gal. iron. Normally, we try to use whatever material
was used in the vessel.
JKlopman <jklo...@aol.com> wrote in article
<199804210210...@ladder01.news.aol.com>...
Tim Moore
Ok, MAYBE stainless shouldn't be used below the water line. However, I'm in the
process of refastening my 41' wooden ketch that was originally put together with
silicon bronze screws and I've come across several stainless steel screws used
when replacing planks. None of these, both above and below the water line,
appeared to be structurally compromised. When I bought this boat, she had not
been hauled out for at least 10 years. (The rest of the boat is another story).
So MY question is: How long will it take for these stainless fasteners to fail??
I have talked to Biloxi boat builder Bill Holland and he uses nothing but
stainless. (See Wooden Boat Mag. #129) And by the way, I am using all silicon
bronze fasteners.
Tim Moore
Mandeville, Louisiana
Kevin Rea
Stainless and all metals need two things to decompose(rust)
Air and Water.
If the fastener is sealed, even below the water line, and no air gets to it,
you probably aren't going to have any rust.
I have pulled 56 year old steel square nails from my hull in the last 2
weeks , below the water line. the ones that were covered well with bondo
were in perfect condition.
The ones that had some exposure, were almost completely deteriorated.
Kevin
Tim Moore wrote in message <353E94B9...@bellsouth.net>...
Pat Ford
On Thu, 23 Apr 1998 20:07:55 -0700, "Kevin Rea" <kr...@email.msn.com>
wrote:
>Stainless and all metals need two things to decompose(rust)
>Air and Water.
>If the fastener is sealed, even below the water line, and no air gets to it,
>you probably aren't going to have any rust.
>I have pulled 56 year old steel square nails from my hull in the last 2
>weeks , below the water line. the ones that were covered well with bondo
>were in perfect condition.
>The ones that had some exposure, were almost completely deteriorated.
In the case of stainless, you are 180 degrees incorrect. Stainless
WILL detriorate (crevice corrosion) in a anaerobic environment.
Again, stainless should not be used underwater.
Tim Moore
I accept this fact (opinion?) but can you qualify this? Again, how long before
any structural degradation of the stainless fastener?? Are we talking about 6
months, 6 years or 60 years. Stainless may not outlast silicon bronze, but it's
all relative isn't it. If sb is good for, say, 200 yrs and ss is good for 100 yrs
what difference does it make. You will no doubt be refastening the hull (or
should be) after 50 - 75 years of service anyway. If this is the case, why not
use the much more avaiable stainless, not to mention less expensive. Once again,
I have seen no evidence at all of any ss failure on my 57 year old boat. Given,
there is very little ss below the waterline, but what there is, is in very close
proximity to the original sb. Neither seem adversly affected.
Tim Moore
Anders Svensson
Hello everybody
Stainless is a little peculiar in that it actually need air (oxygen) to
*not* corrode...
In a underwater situation, any exposed stainless screw will keep up
surprisingly well, as will a hidden one especially if it is well fastened
and "tight". If there is a slight leak around it, and salt water ingress,
corrosion can go quickly. Bronze is the traditional material, but 316
stainless is not bad either, especially if screws are counterbored and
plugged/puttied.
--
Anders Svensson
----------------------------------------
Tim Moore <ti...@bellsouth.net> skrev i inlägg
Jeroen Hoekstra
Hi Time,
SS can corode galvanically within months provided there is NO oxygen and
there is an electrolyte available. No oxygen can happen in any place
where there is a small deep crevice within or between the SS (for
instance between the bolt and nut), the seawater is th electrolyte. The
different metals used to maake the SS alloy will start forming a kind of
battery resulting in sudden, rapid corrosion (weeks to months) which is
difficult to spot till it is too late.
Kind regards,
Jeroen Hoekstra
www.geocities.com/yosemite/3387
David Tew
I have seen an example of a stainless steel bolt fastening deteriorate
via crevice corrosion within six months of installation to the point
where it snapped off easily.
So there's no easy answer to 'how long' it would take to fail. The
quality of the materials, the quality of the installation, and the
electrical 'environment' of the vessel, among other considerations, can
all have a direct bearing on the dependability of stainless fastenings
below the water line.
I agree with Jonathan Klopman and would not use them below the water
line. I go even further in saying that I am suspicious of most stainless
steel fastenings anyway because it's so difficult to find out where they
were manufactured and therefore, what quality standards they meet.
The problem Jonathan Klopman mentioned about thin threads on bronze
screws is another example of reasons to be suspicious about fastenings.
I guess you just have to cull through your supplies.
David Tew
Marine Surveyor
Matt Pedersen
Tim Moore wrote:
>
> I accept this fact (opinion?) but can you qualify this? Again, how long before
> any structural degradation of the stainless fastener?? Are we talking about 6
> months, 6 years or 60 years.
I can add a good data point. I crew on a cold molded boat with a
skeg hung rudder. Her original 316 SS skeg bolts were corroded
through after about 14 years. The replacement SS bolts
(either 302 or 304, aka 18/8 alloy) lasted about nine
months, before the skeg ended up on the bottom of the Pacific
about 300 miles from Acapulco. Fortunately the rudder didn't
follow, and we made it to port.
My advise? Don't use SS below the waterline, but if you do
make sure it is 316, and keep an eye on it.
Matt
John Emmerling
I've been following this thread w/a lot of interest as I have a boat
(1934) that was originally fastened w/gal nails. A previous owner did
extensive refastening in the 70's-80's using gal screws and bondo. A
nightmare at best as many of the screws have corroded or are on their
way because of the bondo. A local shipwright suggested pulling all the
plugs, removing(if possible) and refastening where necessary,cleaning
the gal screw heads,coating w/epoxy, and filling those holes w/thickened
eyoxy to prevent 'bleeders'. Some of the wood around the gal screws is
deteriorated and the epoxy wetout + plugs sounds logical. I might also
add that the boat is wedge seamed and shows no signs of working. This
boat has been to Ak,Mex +S.Pac. I'd like to extend its life and have
stripped the hull to bare wood.
Any suggestions?
Thanks in advance,
John Emmerling
--
Gearhart Ironwerks
PO Box 2080
1368 Pacific Way
Gearhart,OR. 97138
800-738-5434 voice
503-738-5494 fax
Pat Ford
On Wed, 29 Apr 1998 16:17:09 -0700, John Emmerling
<iron...@pacifier.com> wrote:
In my opinion, you got good advice. Galvy fastenings are a pain.
However, they'll make a lot of rust (and stains) before they're gone.
Regards,
pcf
Classic Boat Discussion Board at
Pacific Northwest Antique and Classic Boat Society website: http://www.halcyon.com/pford/acbsx.htm
International Headquarters ACBS: http://www.acbs.org
Andrew Mason
I can only relate my own experience from restoring a 100 year old boat
that had copper, brass, bronze, stainless and galvanised fastenings used
over the years.
I replaced them all (about 4000 fastenings) but the condition of the
fastenings when extracted were as follows -
copper nails and dumps - surface corrosion but otherwise excellent
bronze - good condition but may have been a bit more brittle than when
new.
brass - 1" keel bolts dezicified to 1/2 of their diameter.
stainless - badly pitted and corroded when used below waterline
galvanised nails - badly corroded with resulting "nail sickness" totally
destroying all deck planking and deck beams
As a result I would never use a stainless or galvanised fastening below
water again, and would only use galvanised fatenings where they can be
extracted and replaced or regalvanised in the future. Stainless is fine
above the water, particularly when used with epoxy.
Andrew
Aorere is now sailing -
www.formsys.com/Aorere/Aorere.html
Dr...@rotdoctor.com
In article <3547B4F4...@pacifier.com>,
John Emmerling <iron...@pacifier.com> wrote:
>
> I've been following this thread w/a lot of interest as I have a boat
> (1934) that was originally fastened w/gal nails. A previous owner did
> extensive refastening in the 70's-80's using gal screws and bondo. A
> nightmare at best as many of the screws have corroded or are on their
> way because of the bondo. A local shipwright suggested pulling all the
> plugs, removing(if possible) and refastening where necessary,cleaning
> the gal screw heads,coating w/epoxy, and filling those holes w/thickened
> eyoxy to prevent 'bleeders'. Some of the wood around the gal screws is
> deteriorated and the epoxy wetout + plugs sounds logical. I might also
> add that the boat is wedge seamed and shows no signs of working. This
> boat has been to Ak,Mex +S.Pac. I'd like to extend its life and have
> stripped the hull to bare wood.
>
> Any suggestions?
>
> Thanks in advance,
> John Emmerling
>
> --
> Gearhart Ironwerks
> PO Box 2080
> 1368 Pacific Way
> Gearhart,OR. 97138
> 800-738-5434 voice
> 503-738-5494 fax
>
>
device that would fit in an electric drill, ground all the heads down to
bright metal, epoxy saturated the hole and then filled back in with epoxy
putty. Bitchy job, and the boat dried out so much she damn near went to the
bottom when we re-launched. Sailed her all around the Pacific and back without
any problems. Galvanized fastenings are a hassle, but are strong and last
longer than a lot of folks think. The only thing I would do differently now is
use the Clear Penetrating Epoxy Sealer in the holes before the thick epoxy.
Better penetration and will follow the fastening shank down into the plank/
frame.
The Rot Doctor
http://www.rotdoctor.com
E-mail: Dr...@RotDoctor.com
Phone: 206 783 0307
Fax: 206 783 0582
David Tew
Doesn't refastening and plugging with epoxy create problems for future
refastening work?
I personally haven't tried to remove epoxy "putty" or bungs/wood plugs
set in epoxy or galvanized screws bedded with epoxy, but it sounds too
permanent for easy renewing. Comments from someone who has had to deal
with this?
David Tew
Marine Surveyor
Norman Hirsch
Mixed fastenings below the water line are not a good idea. If you
had galvanized to start with, your best solution is to use galvanized
for all future fastenings. Galvanic corrosion will cause the
galvanized nails to go quickly if you put anything like stainless as a
replacement for some and not all of the fasteners.
--
GFPete2
This post is getting me very nervous. Im 2/3 of the way done on a VERY
large resto of a 1957 33 ft cruiser.(Chris Craft Futura)I have used stainless
screws EVERY where,above and below the water line. BUT guys I have been useing
them for years on way to many projects to remember,and have taken apart my own
TEMP. repairs 5 years later with no sighn of pitting. Could there be less
problem in fresh water? and why havent my monel prop shafts fallen out of the
boat?
Pat Ford
Maybe you have led a particularly righteous life?
I'm no metalurgical expert but I think it's fair to say that stainless
degradation is very unpredicatable. Absence of oxygen is the main
consideration. Thus, if you use your boat a lot maybe it get oxygen to
fasteners??
Monel is not stainless; it is a very stable alloy.
Matt Pedersen
GFPete2 wrote:
Could there be less
> problem in fresh water? and why havent my monel prop shafts fallen out of the
> boat?
You need the presence of chloride in some form for crevice
corrosion to be a problem. If your fresh water is
relatively unpolluted, you won't suffer as much
as the salt water boats do.
Monel is not a stainless steel. It's an alloy of nickel
and copper, so it doesn't suffer from crevice corrosion
the way stainless does.