Best Marine Soldering Practices

[David M]

On commercial vessels, the Code of Federal Regulations (CFR's) ban soldering wires that provide power. Data is okay. The reason is that if a circuit gets overloaded then the solder joint could melt, causing the wires to separate and an electrical fire could cascade as the now loose wires touch other wires or ground to an aluminum hull for example.

A lot of times the CFR's are written to cover real life examples of something that actually happened.

I tend to agree with the CFR's.

[SV_Kuleana]

Originally Posted by GordMay

Indeed.
However, I'd encourage noelex to continue this tutorial.

Yep. The tutorial is to teach people the "second-best" practice, because the industry standard best practice is: "Don't solder". So, all this banter about the best way to do it wrong is just that. Wrong.

[kmacdonald]

Originally Posted by SV_Kuleana

Yep. The tutorial is to teach people the "second-best" practice, because the industry standard best practice is: "Don't solder". So, all this banter about the best way to do it wrong is just that. Wrong.

I agree!!!!!!!!!!!!!! Don't solder!!!!!!!!!!!

[keyway]

Back in the day I was a Navy avionics repaire technician trained to repair to NASA standards. It’s one thing to work at a nice bench repair station but another thing in the bilge of a boat. For joining two wires of same gauge the western union splice soldered is really hard to beat. I like the heat shrink with the potting compound inside it so it melts an squeezes out when you heat it up. I usually use a butane soldering iron with the open flame and hold the solder in my teeth. It helps to use heat shuts at the insulation to prevent the solder from running under the insulation small alligator clips work ok. The pre tinned marine wire solders beautifuly so I try to use it when I can. Sometimes it’s just not feasible to solder so a proper crimp will just have to do.

[EngNate]

A problem with soldering terminals and lugs is that the solder will wick up into the wire and that portion of it becomes solid and can break from flexing action. It's not an issue with inline splices but can be when the end is secured to a termination. Another problem is oxidized wires which result in a poor soldered connection even though it may look good on the surface. Just about every wire that lives in a boat will have an oxidized surface, it begins at a terminated end and creeps along the inside by capillary action. Given time it will go all the way from the bilge to the flybridge. Compression connections are much more reliable here, besides the fact that they are much easier to do properly. Parts to be soldered must be clean and bright, it really should be done only with new or like new wire and terminals. Often terminals and lugs are oxidized just from shelf life.

You can't get them without buying direct in large quantity, but there are terminals made for soldering and you can modify yours. They have a hole halfway down the barrel. Make a compression crimp on the wire side of the hole, apply heat to the terminal pad (solder flows toward the heat), allow enough time for conduction to heat the wire inside and apply the solder into the hole, stop as soon as the hole fills. Continue heating so the molten solder will bring the wire core up to temperature and flow in, add a little more solder as necessary when the hole goes dry. When properly done no solder will be drawn into the wire, and minimal damage will be done to the insulation. Large terminals require a pencil torch with a tiny hot flame.

I have seen soldered cable ends where the solder has melted out because the actual connection inside was poor. I've been shown other ends that were just done and I put the terminal in a vise, gave a sharp yank on the cable and pulled it out. "there's nothing wrong with this connection" "there is now..."

For the best cable connection treat the cable with a conductive compound such as T&B Copper-Shield, use the correct size compression connector, crimped with the right tool and the dies or setting that match the terminal. This is the method used throughout industry, power plants, electric utilities, etc. The less expensive indent type crimpers really aren't good for marine use. They don't make a tight connection to all the cable, and they leave large gaps where moisture gets in. A better tool in the lower cost range is made by T&B. It is adjustable and makes a triangular crimp, the coverage around the cable is fairly good, and you can adjust it for differences in terminals. Die type crimpers must be used with the specified terminals, thinner wall barrels will not be crimped properly.

I've done a lot of soldering, I imagine 10's of 1000's of connections over 40 years, wires, cables, pcb build & rework including SMT, even salvaging and re-using surface mount chips. It is my preferred method for inline splices in electronic cables but otherwise I rarely do it on a boat.

I will never give up my 40+ year old Weller iron, as long as I can find replacement parts on ebay or elsewhere. Nothing else I've used has both the power and control to get the heat into the parts, do the job, and get off it without doing damage.

A very important point in soldering is that the parts to be connected must be raised to the temperature that melts the solder - the solder should melt on the parts without having to touch the tip. A little bit of solder on the tip, between it and the parts, greatly helps conduct the heat to the parts. Otherwise, the solder should never be applied to the tip, only to the parts which have become hot enough to melt it. Solder flows toward the source of heat, observe that factor to get even coverage on a larger connection.

[col50]

Originally Posted by Jim Cate

Re the annealing question: You don't anneal something by quenching it. Rather you let it cool slowly. For copper wires, their high thermal conductivity means they will cool fairly quickly once t he heat source is removed, but in my experience they remain flexible outside the actual soldered area.

A practical way to anneal copper things like gaskets and crush washers (when replacement is not possible) is to use a candle or acetylene torch to soot them up. Then heat just until the soot burns off, then set on a non heat conductive surface and let cool. They will be in a soft, annealed state.

Jim

Sorry Jim, annealing copper and copper alloys is not the same as annealing steel. Unlike steel, the annealing of Copper and aluminum and other metals is done by heating and quenching.
More info: https://en.wikipedia.org/wiki/Annealing_(metallurgy)

[Jim Cate]

Originally Posted by col50

Sorry Jim, annealing copper and copper alloys is not the same as annealing steel. Unlike steel, the annealing of Copper and aluminum and other metals is done by heating and quenching.
More info: https://en.wikipedia.org/wiki/Annealing_(metallurgy)

Hmm... that link lead to an empty page for me.

But many years of annealing copper crush washers by the method I describe has resulted in soft, reusable items. It works...

Jim

[Shaneesprit]

Originally Posted by thinwater

I've tested some of these. They can be good, but they can also be awful, depending on the solder used, the tubing, and other design factors. Some are worse than just twisting wires together.


I'm not sayin' there are not good ones, but don't believe all you read. After testing, I either crimp or solder manually and heat shrink.

Doomed to failure, if I saw crimps like this used in production of the machines i work on, well i have done and its probably best, you only have to look at the DIY crimping tool used to know that your looking at something that will be inconsistent, the fact that the crimp allows the wires to pass suggests its going to be unreliable
older style crimps are unreliable - that why my dad always solders and i almost always crimp

https://www.youtube.com/watch?v=gh9DxLeF3Hs&t=267s

[RaymondR]

I had soldered all the wiring on my old boat wherever practical then used heat shrink with a good shot of hot melt glue into it. I reheated and fully shrunk the heatsink which squeezed the excess glue out which I then trimmed off. Never had a joint failure in the 35 years I owned the boat.

[Lake-Effect]

Originally Posted by RaymondR

I had soldered all the wiring on my old boat wherever practical then used heat shrink with a good shot of hot melt glue into it. I reheated and fully shrunk the heatsink which squeezed the excess glue out which I then trimmed off. Never had a joint failure in the 35 years I owned the boat.

Soldering is a very useful skill and this thread has provided some good tips (pun intended) and advice.



The thing is - person A can solder all his connections and never have a problem (skill, luck, or both); person B can try to solder all his connections, fail at many, and have several that will go bad later.


But both A and B can go into Wet Marine, buy lugs and the controlled cycle crimper, and they will both make satisfactory connections. Easier to test too (give it a tug). In other words, crimping is most likely to produce good results even in mediocre hands. That's a big part of why it's recommended so often.

[Mick C]

It was mentioned briefly above “solder wicking up the wire” and my understanding is that in scenarios where vibration and other movement is normal one of the risks of solder joints is potential brittleness in the cable up from the joint. I tend to mechanically join for this reason so I would love to hear your comments on this issue, is it fact or fiction.

I know lots of people have had 100% success with 1000s of soldered joints so I’m not looking for an absolute answer, just your opinions on the problem.

My concern is that if a solder joint is brittle just past the solder and we put a shrink wrap or hot glue etc over the whole joint then it might be the shrink wrap or glue holding the wires together even if a crack develops.
Regards
Mick

[col50]

Originally Posted by Jim Cate

Hmm... that link lead to an empty page for me.

But many years of annealing copper crush washers by the method I describe has resulted in soft, reusable items. It works...

Jim

Jim,
I don't know why the link doesn't work. Try this one. It works for me.

https://en.wikipedia.org/wiki/Annealing_(metallurgy))

[Jim Cate]

Originally Posted by col50

Jim,
I don't know why the link doesn't work. Try this one. It works for me.

https://en.wikipedia.org/wiki/Annealing_(metallurgy))

Yep, that one worked... and it says that I was right... slow cooling works for copper. It also says that you were right... rapid cooling works for copper. Versatile stuff, it is.

"In the cases of copper, steel, silver, and brass, this process is performed by heating the material (generally until glowing) for a while and then slowly letting it cool to room temperature in still air. Copper, silver[1] and brass can be cooled slowly in air, or quickly by quenching in water, unlike ferrous metals, such as steel, which must be cooled slowly to anneal. In this fashion, the metal is softened and prepared for further work—such as shaping, stamping, or forming."

Jim

[S/V Illusion]

Originally Posted by Lake-Effect

Sure, but first, it's not obvious to everybody that high-current connections on boats must be primarily mechanical... so that's why it gets a mention.


Second... if you've made a high-quality, gas-tight mechanical connection - eg a properly crimped lug... there's usually no compelling reason to solder it as well; the crimping has done the job. I know some folks who like to apply some solder into the exposed end of a crimped lug, for example... but if you do that poorly, you've just melted some plastic and insulation, and probably made the connection more brittle.

In your example of a gas tight crimp, the solder cannot wick into the connection which makes soldering useless. That's not what I was talking about. Rather,it's impossible to know if any crimp is in fact tight unless you cut it open to examine it. The inability to ensue crimps are good is their fundamental flaw and the reason they shouldn't be used. Ever!

As to the issue of movement which can weaken a cable at the solder interface, that's only possible if the cable isn't mechanically fastened first. Not mechanically fastening connections is the real reason soldered joint fail. If it's done properly, soldering beats crimping in any scenario.

[col50]

Originally Posted by Jim Cate

Yep, that one worked... and it says that I was right... slow cooling works for copper. It also says that you were right... rapid cooling works for copper. Versatile stuff, it is.

"In the cases of copper, steel, silver, and brass, this process is performed by heating the material (generally until glowing) for a while and then slowly letting it cool to room temperature in still air. Copper, silver[1] and brass can be cooled slowly in air, or quickly by quenching in water, unlike ferrous metals, such as steel, which must be cooled slowly to anneal. In this fashion, the metal is softened and prepared for further work—such as shaping, stamping, or forming."

Jim

Another interesting thing to know is that some copper and aluminum alloys will harden when kept at a certain temperature for a certain minimum amount of time.
The process is called aging, because it can happen even at room temperature given enough time.