I realize that this might be a prompt for lots of argument but anyway....

I have just started rewiring the 12V side of my boat. While ripping out
the miles of cable that seemed to power big blobs of ancient insulating
tape I have noticed that the continued wire seems to have survived well.
i.e. the boat is 20 years old and the original stuff is which was mainly
continued is fine. I can see no signs of corrosion even after stripping
large lengths. The insulation is a different matter in some cases. It is
in a poor state, especially were it is exposed to heat or sun but that
is a different issue.

So the question is: Is tinned copper really necessary? It is more than
twice the price of pure copper and has the same insulation! I am
prepared for quotes from various recommendations and standards (many of
which I have read) but what I would really like is some real empirical
engineering info here. I have been involved in standards bodies and know
how they work. Good ideas can very easily become mandatory requirements
because it could be critical in some obscure cases. I was trained as an
engineer which is to say I can live with the concept of good enough for
purpose. If the life expectancy of pure copper is half that of tinned
and tinned will last 30+ years, I can live with having to change the
wire again in 15 years.

Steve

"Steve" wrote in message ...
I realize that this might be a prompt for lots of argument but anyway....

I have just started rewiring the 12V side of my boat. While ripping out
the miles of cable that seemed to power big blobs of ancient insulating
tape I have noticed that the continued wire seems to have survived well.
i.e. the boat is 20 years old and the original stuff is which was mainly
continued is fine. I can see no signs of corrosion even after stripping
large lengths. The insulation is a different matter in some cases. It is
in a poor state, especially were it is exposed to heat or sun but that is
a different issue.

So the question is: Is tinned copper really necessary? It is more than
twice the price of pure copper and has the same insulation! I am prepared
for quotes from various recommendations and standards (many of which I
have read) but what I would really like is some real empirical engineering
info here. I have been involved in standards bodies and know how they
work. Good ideas can very easily become mandatory requirements because it
could be critical in some obscure cases. I was trained as an engineer
which is to say I can live with the concept of good enough for purpose. If
the life expectancy of pure copper is half that of tinned and tinned will
last 30+ years, I can live with having to change the wire again in 15
years.

Steve

If the ends of the wire can be sealed from moisture then non-tinned wires
will work fine. I've seen corroded wire up more than a foot under the
insulation. If tinned wires is used then one can use crimped connectors
without
sealing the ends.

Doug

Steve wrote:
I realize that this might be a prompt for lots of argument but anyway....

I have just started rewiring the 12V side of my boat. While ripping out
the miles of cable that seemed to power big blobs of ancient insulating
tape I have noticed that the continued wire seems to have survived well.
i.e. the boat is 20 years old and the original stuff is which was mainly
continued is fine. I can see no signs of corrosion even after stripping
large lengths. The insulation is a different matter in some cases. It is
in a poor state, especially were it is exposed to heat or sun but that
is a different issue.

So the question is: Is tinned copper really necessary? It is more than
twice the price of pure copper and has the same insulation! I am
prepared for quotes from various recommendations and standards (many of
which I have read) but what I would really like is some real empirical
engineering info here. I have been involved in standards bodies and know
how they work. Good ideas can very easily become mandatory requirements
because it could be critical in some obscure cases. I was trained as an
engineer which is to say I can live with the concept of good enough for
purpose. If the life expectancy of pure copper is half that of tinned
and tinned will last 30+ years, I can live with having to change the
wire again in 15 years.

Steve

I had a similarly aged boat and the older wire varied a lot when
removed. Some of the wire was black with corrosion, some was just a
little dull, and some was shiny. More exposed wire, or wire where
wicking from outside fixtures was possible tended to suffer more.

Is tinned wire necessary? Probably not inside the boat for
non-critical systems like cabin lights. For instruments, and
navigation lights I'd say bite the bullet and use tinned wire. But do
shop around. Many makers of tinned wire sell spools of wire for a lot
less than Ancor at the local West Marine! One fellow regularly sells
on ebay.

Oh, on my boat all new wire is going to be tinned. Thankfully the
electrical system currently consists of 4 lights, 2 nav lights
(tricolour and masthead), a VHF, GPS, and depthsounder. It's rather
spartan right now in the electrical department.

Evan Gatehouse

One thing I have noticed after working with several brands is that marine
grade wire is built up from much smaller strands than the standard wire you
get at Home Despot. That makes them more flexable and less prone to fatigue
breaks.

If you do some looking you can find some great deals of marine wire. I
figure I have more than a mile of wire in Rutu and have never paid much more
than 50% of list price.

--
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

Hello Steve,

You have my sympathy. Getting the quantitative data you're
looking for seems near impossible.

To my understanding, admittedly subject to recalibration,
neither the USCG nor the ABYC standard requires tinned
copper conductors.

The ads often read "our tinned copper wire meets ABYC
standards" suggesting that tinning is part of the standard,
when the conformance reference is technically to stranding,
insulation, and color!

We know that tin oxidizes more slowly than copper, and that
the copper oxides that form when copper corrodes are
non-conductive.

Beyond that, all I can find are anecdotal and largely
unscientific reports, and the "tinned copper reduces
corrosion" mantra.

Good luck

Chuck

Steve wrote:
I realize that this might be a prompt for lots of argument but anyway....

I have just started rewiring the 12V side of my boat. While ripping out
the miles of cable that seemed to power big blobs of ancient insulating
tape I have noticed that the continued wire seems to have survived well.
i.e. the boat is 20 years old and the original stuff is which was mainly
continued is fine. I can see no signs of corrosion even after stripping
large lengths. The insulation is a different matter in some cases. It is
in a poor state, especially were it is exposed to heat or sun but that
is a different issue.

So the question is: Is tinned copper really necessary? It is more than
twice the price of pure copper and has the same insulation! I am
prepared for quotes from various recommendations and standards (many of
which I have read) but what I would really like is some real empirical
engineering info here. I have been involved in standards bodies and know
how they work. Good ideas can very easily become mandatory requirements
because it could be critical in some obscure cases. I was trained as an
engineer which is to say I can live with the concept of good enough for
purpose. If the life expectancy of pure copper is half that of tinned
and tinned will last 30+ years, I can live with having to change the
wire again in 15 years.

Steve

In article , chuck
wrote:

We know that tin oxidizes more slowly than copper, and that
the copper oxides that form when copper corrodes are
non-conductive.

Beyond that, all I can find are anecdotal and largely
unscientific reports, and the "tinned copper reduces
corrosion" mantra.

Good luck

Chuck

also be advised that Copper wire in the presents of Battery Acid fumes
corrodes extremely quickly into copper sulfate, (Blue Powder) and that
doesn't conduct electricity very well at all. The tin plating provides
a good protection from this type of corrosion, the same as it does for
Salt Water vapors.


Bruce in alaska also a retired chemist, from way, way back......
--
add a 2 before @

Good point but unfortunately the only wire of sufficient conductor area
(16+mm^2) I have been able to find that goes anywhere need the batteries
is just untinned copper. In this case I have used welding cable because
it has better insulation than other stuff I have found. I have also
sealed the ends well.

If the stuff I am talking about here (1-2 mm^2 from the dis panel) is
getting battery fumes I am in real trouble!



Bruce in Alaska wrote:
In article , chuck
wrote:


We know that tin oxidizes more slowly than copper, and that
the copper oxides that form when copper corrodes are
non-conductive.

Beyond that, all I can find are anecdotal and largely
unscientific reports, and the "tinned copper reduces
corrosion" mantra.

Good luck

Chuck


also be advised that Copper wire in the presents of Battery Acid fumes
corrodes extremely quickly into copper sulfate, (Blue Powder) and that
doesn't conduct electricity very well at all. The tin plating provides
a good protection from this type of corrosion, the same as it does for
Salt Water vapors.


Bruce in alaska also a retired chemist, from way, way back......

All,

Thanks for the replies. It should mention that just about all the wire I
am working on at the moment is internal to the boat.

I think I will continue to use the untinned wire (bargains on marine
cable are not common in NZ) but seal the ends as suggested. I am aware
of the issue with fatigue if the copper is too thick and so will use
something with lots of thin strands. I also solder all the small crimp
connectors as well as crimp them which I believe will offer some protection.

For the nav lights (front, back and mast) I an leaving the existing wire
in place as it is tinned and in excellent condition.

Thanks again,

Steve

Bruce in Alaska wrote in news:bruceg-
:

also be advised that Copper wire in the presents of Battery Acid fumes
corrodes extremely quickly into copper sulfate, (Blue Powder) and that
doesn't conduct electricity very well at all. The tin plating provides
a good protection from this type of corrosion, the same as it does for
Salt Water vapors.


Bruce in alaska also a retired chemist, from way, way back......


There you go, Bruce....ruining good towing jobs when the cheapskates'
wiring rots through putting them in the dark.....(c;

Keep an eye out behind you! One of those tow guys may take a pot shot!!

"Steve" wrote in message ...
All,

Thanks for the replies. It should mention that just about all the wire I
am working on at the moment is internal to the boat.

I think I will continue to use the untinned wire (bargains on marine cable
are not common in NZ) but seal the ends as suggested. I am aware of the
issue with fatigue if the copper is too thick and so will use something
with lots of thin strands. I also solder all the small crimp connectors as
well as crimp them which I believe will offer some protection.

From what I have read, solder and crimping is not a good idea. Soldering is
not neccesary when using a proper crimp connector. Soldering has a number
of drawbacks. A good crimp connection that is sealed against moisture
is about as good as it gets.


For the nav lights (front, back and mast) I an leaving the existing wire
in place as it is tinned and in excellent condition.

Thanks again,

Steve