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lorenzo b 17-06-2009 06:03

Tinned Wire?
Every book I've looked at about marine electrical systems insists that only tinned stranded wire be used on a boat, so when I started getting bids from marine electricians and talking to commercial boat owners down here in the Louisiana oil patch I asked if they used tinned wire. Not a single one said yes. They had heard of tinned wire and offered to use it if I wanted, but said it would add 10k to the price and that I didn't need it. They explained that the normal insulation on stranded wire was sufficient to protect the copper and only the stripped ends at the connections would be exposed. They claimed that if the connections were properly crimped, soldered if appropriate, and sealed with heat shrink that I should not have a problem.
Any thoughts on this?

Maddog 17-06-2009 06:15

Practical Sailor came out with an editorial that said the same thing. It opened up my eyes. Be sure to use plenty of vasiline on the crimps. Search the threads we had a lively discussion on the subject.

Southern Star 17-06-2009 06:23

I have always used tinned wire for replacement/upgrades and suggest that you would be wise to do the same: in effect, do it it right the first time. The problem with their analysis is:

1. The insulation will break down over time due to the effects of movement/chafe, heat, moisture and UV rays, despending upon exposure.
2. Even heat-shrink connectors/eye terminal etc. are not foolproof - in fact, as they are less flexible than the wire itself, they are frequently the weakest link.
3. On a boat, electrical failures when underway can be far more than an inconvenience.
4. The cost/effort to hunt down shorts and then re-wire will inevitably have you seeing the use of non-tinned wire as a false economy.

In addition, I find it difficult to believe that the cost increase would be 10k for your project. When bought in bulk, the cost of tinned wire comes down substantially. You could do a hybrid job, if the cost seems prohibitive: use tinned wire below the waterline, on the exterior (including running lights etc.), in any area where access will be a problem or where the wiring is to a critical component (eg., the autopilot, but not the stereo, etc.). But in the end, I think you will find that when you factor in the cost of good quality heat shrink connections/ends and labour (which will be a constant) and the limited amount of wiring that is non-essential, you may as well go with all tinned wire.


James S 17-06-2009 06:29

Hmmm....well when I ordered the wire for my refit, I ordered tinned.

Some of the old wire that I removed was not tinned (the vast majority was tinned) and although there was visible tarnish on the ends I really hadn’t had a problem with the un-tinned ones

From what I’ve read about your boat and your intensions its hard to imagine that the price difference could be that high.

If you don’t go with tinned after all that work in rewiring are you always going to have that worry in the back of your mind?

If you don’t go with tined and have a failure in a connection how will that effect the operation of your pride and joy?

Perhaps there are areas that would be worth using tinned and others that are not that critical from a safety point of view.

It’s a tough call mate!

I say if you can afford it, and for the sake of “peace” of mind and good nights sleep go for the tin.

If the extra cost means you’ll not be able to have your great adventure…..screw it and go with what ever you can afford.

GordMay 17-06-2009 06:34


Originally Posted by lorenzo b (Post 294116)
... so when I started getting bids from marine electricians and talking to commercial boat owners down here in the Louisiana oil patch I asked if they used tinned wire. Not a single one said yes. They had heard of tinned wire and offered to use it if I wanted, but said it would add 10k to the price and that I didn't need it.

How many MILES of wire do they expect to install for that $10,000 premium?

Wotname 17-06-2009 06:36

How long do you want the wiring system to last? If 10+ years, use tinned.
Will you have to ever significantly rework the wiring system? If yes, then use tinned.
What size job is it to increase costs by $10K?
I have to agree with S.Star.

Bash 17-06-2009 06:43

another eye opener
for me, another eye opener was to discover that ABYC standards insist on stranded copper wire but not on tinned wire.

regardless, I'd worry about resale. I think a lot of prospective buyers would walk away from a survey that pointed out that the boat was not wired with marine-grade materials. I certainly would.

sneuman 17-06-2009 06:58

The original wiring in my boat (now 30+ years) is not tinned and it has not been a problem, despite a lot of use including a circumnavigation a decade ago (under a previous owner). Salt air and tropical heat are the biggest natural corrosives in the marine environment, and this boat's wiring has experienced plenty of both.

If new non-tinned wiring will last another 30 years, I'm OK with that.

Randy 17-06-2009 07:36

A few thoughts. The $10k figure kind of says the electrical contractors don't want to be bothered. Like Gord says ballpark the footage of wiring & guess the difference.

If you've got insulation breakdown in your wiring the least of your concerns is copper corrosion (you'll have shorts & high risk of fire).

If stranded copper meets ABYC requirements how is that not 'marine grade'?

The connections really are the critical link and if properly crimped & sealed with heat shrink that link should be clean. The physical attachment of the connector is another potential problem area. Where electrical problems have been in my own experience were the simple connections. Say a light bulb in a running light having poor connection because of corrosion cuz the unit wasn't sealed well.

So to me while tinned seems worthwhile it doesn't seem critical to me. And the question I think everyone has is what's it really going to cost. I wouldn't spend any where near 10k with my budget, I would spend a few hundred.

Bash 17-06-2009 08:07

good question

Originally Posted by Randy (Post 294147)
If stranded copper meets ABYC requirements how is that not 'marine grade'?

I know that there are other standards than ABYC. For example, there is a UL standard that specifies insulation requirements for withstanding immersion in hot oil. I don't believe the UL standards require tinning either, but I should point out that there are multiple standards, and I'm no expert in this area. ul-1426.4

If someone wants to do more in-depth research, other standards that apply to marine wire in various applications:
UL Standard 1426 (BC-5W2)
AWM 1015/1230 (16-10 AWG)
AWM 1028/1231 (8 AWG)
ABYC: E-8.14, E-9.14
Coast Guard: 33 CFR part 183

David M 17-06-2009 08:23

This is a tough call.

I operate a boat that was built in 1975. The original un-tinned, stranded wire is still fine. This wire though is in places where in general there is not a whole lot of humidity such as for the overhead lighting. The original wire that I have replaced is in places where there was typically a lot of humidity such as in the bilge areas. (My bilges are never completely dry.)

You could probably get away with un-tinned wire if you do a super job on your connectors. This would mean using expensive heat shrink connectors. Where you could not use heat shrink, I would coat all the wire and crimps not with Vaseline (which eventually drys out) but with Tef-Gel or silicon grease...with Tef-Gel being more water resistant and more resistant to hardening.

With tinned wire, if your air tight seal does fail, you are more protected than if you have bare copper exposed to oxygen.

Another consideration is capillary action. Water can get absorbed back into the wire insulation. I have stripped back as a much as a few feet of wire in order to get to clean, bright uncorroded wire. Unfortunately, you cannot see this corrosion. Tinned wire will not stop capillary action but it will slow down its negative effects. I always try to put some sort of liquid goop where the wire is stripped back to the insulation, if I am not using heat shrink.

Others made an excellent point that when you go to sell the boat, if a new buyer sees that the boat has un-tinned wire, then that may be a deal breaker or force you to sell the boat for less money. I actually saw Romex and wire nuts on a boat once. :eek:

I think you could get away with using un-tinned wire if you are super careful. I always replace my wire with tinned wire though. This gives me peace of mind that I don't necessarily have to be perfect with my electrical connections all the time.

Capillary action

Cheechako 17-06-2009 09:13

The best boats have used tinned wire for many years. It is a little more expensive, but I would run fast from a contractor that told you $10k. Plain Copper will last quite a while fine, but if you are in the loop on boat rebuilding forums and complaints.... what is one common complaint about old or Taiwanese boats?.... that's right, people have to rewire the boat. The wiring is copper without tinning. Most often the problem is the ends or the wire terminals on any boat. The end terminals get corroded inside and connection is lost or becomes intermittant. I have cutback many wires on boats to try to put a new terminal on, but the corrosion goes deep in the plastic jacket sometimes for inches. If your contractor will crimp and solder every fitting and use the terminals with the built in shrink wrap (the ones with the gooey glue that seals them) go for it, it will cost him far more than tinned wire!

hellosailor 17-06-2009 09:35

"They explained that the normal insulation on stranded wire was sufficient to protect the copper "
Well, they're wrong. Ask anyone who has tried to field-repair some punked out green untinned wire on an old boat. You lop a foot off the end, the green crud is still up there. Lop off another foot, another foot...ten feet up you may still find crud and punked out wire.
The problem is of course worse with stranded wire, rather than solid wire. But solid wire is inappropriate because it work hardens and can fail faster--unless it is rigidly affixed all the way. The strands always have some air space between them, or will develop air space as they move and work, no matter how well the insulation has bonded to them. Then as the boat heats and cools, the air in the wiring expands and contracts and each cooling cycle sucks in more moist air, which corrodes the wire more.
Physics, not magic. How bad the problem is, how much you can get away with, depends on your luck and the environment. Maybe your builders are used to a brackish area--not full salt water and salt air. Maybe they're used to nice big heated boats.
And if the insulation is spliced, cut, chafed, pinholed...again moisture can get in at any point, which is why you need to protect more than just the ends. IF you have untinned wire, and IF you do a very good job sealing the ends, and IF the insulation is bot penetrated, sure, you might keep the water out. But physically running the wire on a boat can be such a PITA (under, over, around, through) that the price of using the right wire the first time is usually way cheaper than the price of redoing it after some bozo decided zip cord would be good enough.

Buthey, if they will offer you a 30 year warranty on their work, using the wrong wire, with them coming to the boat and performing repairs when and as needed...Go for it. Let them back up their opinion with their wallets.

CharlieJ 17-06-2009 15:33

There is more to the conductors you are going to use then just the tinning; and to my way of thinking, these factors are far more important.
1. Size: Make sure that your contractors are going to provide AWG wire; and NOT SAE wire. AWG conductors, on average, have 12% more copper than similarly sized SAE conductors.
2. Stranding: ABYC E-11 allows the use of Type 2 stranding but Type 3 is the industry standard and is to be used in areas subject to flexing. As and example; AWG 1/0 Type 2 wire has 127 strands whereas 1/0 Type 3 has 1,064 strands.
3. Insulation: The ampacity of conductors is generally determined by the high temperature capacity of the insulation. Boat Cable BC5W2, UL 1426 has insulation rated at 105C dry/75C wet.
4. Crimping: Ensure that the terminations are the double crimp type and that the contractor uses a ratcheting double crimp tool to attach the terminations to the conductor.
5. Soldering: Don't. Except for the bonding system, if you install one.

I bring these details up to make sure that your contractors are giving you the correct product...there is a lot of SAE Type 2 wire out there and it is a PITA to work with.

Tinning is nice to have. ABYC E-11 does not currently speak to it either positively or negatively. I have several miles of wire in my shop. All tinned. It is all going into boats that are going to go to sea. In my opinion, not the place to skrimp.

Regarding adhesive filled terminations. My advice is to use them judiciously where they may be exposed to water. Heat shrinking every termination is not warranted and would greatly increase the material and labor cost for your wiring.

$10k price way UNLESS they were quoting you originally for SAE wire without the BC5W2 certification. Even way.

Hope this helps.

RainDog 17-06-2009 16:06

A simple search for tinned copper wire shows a retail price of about $1 a foot (ANCOR 108025 Ships Store Torresen) for 10 gauge. That means even if your marine electrician is 1) paying retail 2) using 10 gauge 3) getting untinned for free - his quote must still be for 10,000 feet of wire. If your boat is 40 feet that would be over 200 circuits. That does not make any sense and you should challenge them on that.

As others have mentioned, I think this all depends on how long you plan to keep the boat. If less than 15 years, I do not think it will make any difference for you. If over 15 years then it appears experts disagree, but you still should be paying a MUCH smaller premium. I think even on a very large job you could get tinned wire for < $1000 more if you do your research.

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