Copper wire for marine use?

[RhythmDoctor]

I am continuing preparations for installing an automatic bilge pump. Wire routing is going to be very tight. I had hoped to use Ancor 16-3 Triplex Wire, but thanks to the multiple insulation layers it will not fit through some nice existing conduit and routing holes. I have some nice trailer lighting wire which is stranded copper, 16 gauge, 4 conductor (which could come in handy if I decide to someday install a separate float switch instead of the fully automatic pump I currently have). Its ribbon shape will fit through my existing conduit nicely. The main issue would seem to be that the wire is not tinned - it is 100% copper.

What are your suggestions?

[Gene T]

Untinned wire in a bilge will fail eventually. All of my boats have had untinned wire somewhere, some more than others. But I don't use it and definitely would not use it in a bilge and especially for a bilge pump. You could crimp then solder then seal with something but it will fail eventually anyway. Do it if you have to because of time restraints but plan on changing it at some point. I recently replaced a ground braid on my boat that turned to dust. That happens to unprotected copper.

Gene

[hellosailor]

Doc, you can either find a way to use tinned wire, or use the trailer wiring and look forward to having it gradually fail, perhaps overheating, and needing replacement within five years. Maybe as little as six months, depending on how lucky you are.

You say there's existing (bushings?) and conduit, what used to run in them? Jacketed triplex wire is usually meant to be run without conduit, just supported and bushed as necessary. You may have to either remove the conduit, or run different wire, but do what it takes to do it right--with tinned wire of adequate diameter.

[mitiempo]

I'd use only tinned wire, especially in a bilge. All connections covered with adhesive heat shrink.

Also, you should never need the 4th wire. All auto bilge pumps that I've installed, integral float switch or separate float switch, use 3 wires. Ground, manual + and auto +.

[RhythmDoctor]

Originally Posted by hellosailor

Doc, you can either find a way to use tinned wire, or use the trailer wiring and look forward to having it gradually fail, perhaps overheating, and needing replacement within five years. Maybe as little as six months, depending on how lucky you are.

You say there's existing (bushings?) and conduit, what used to run in them? Jacketed triplex wire is usually meant to be run without conduit, just supported and bushed as necessary. You may have to either remove the conduit, or run different wire, but do what it takes to do it right--with tinned wire of adequate diameter.

The conduit has active wire going through it, so I will not remove it. But maybe I should remove it just in case it's copper. I can see from the control panel that this boat has some copper wiring in it.

I had forgotten when I posted my message that my Trophy boat has its bilge pump wired with copper. Going on 15 years and working fine, and much more exposed to the elements than this boat. Maybe I'm just lucky - or maybe it's the fact that none of my boats have ever seen salt water. Then there's the trailer also, which not only gets constant exposure to the elements but huge amount of vibration that could make the wire brittle. No problem with that either after almost 20 years, and I check it every year.

FYI, this boat has a bone dry bilge. Outboard motor means no gland to pack - at least not in the bilge. The only below water line through hull fitting is the head intake which I always keep turned off. There is a manual pump that came with the boat. The only purpose of this automatic pump is in case we get a slow leak when I'm away for a couple weeks. But so far not a single drop of water in the bilge. So the wires are not exposed to much moisture there.

[mitiempo]

If you keep the boat in you driveway it will never get damp, but on the water the air is moist and it will corrode. I have removed old wire from many boats, from "dry" locations and found corrosion many feet in from the end. Black copper does not conduct well. The best cable in my opinion is the Ancor bilge pump cable. Grey insulation over black, brown, and red conductors and the outer jacket is both oil and water resistant. It is a round cable and if it doesn't fit you can always drill a few holes and install grommets to do it right. I'd also use 14/3 instead of 16/3. The only items I use 16ga for on a boat are LEDs and short instrument runs.
The bilge pump wiring should be the only wire in the bilge ideally.

[Maine Sail]

Will it work? Yes, but the question becomes for how long and will it be in working order when you finally need to rely on it.. In fresh water, with hermetically sealed adhesive lined heat shrink crimps, and a good quality wire (trailer wire is generally quite poor quality) it should last a good long while. 16Ga may be light for a bilge pump unless it is a short wire run and or a small pump.

I always find this photo amusing. Keep in mind wire nuts are verboten on boats but some DIY's use them anyway. These two wires were installed on the same day and in two years this is what they looked like. The tinned wire is like new the bare copper badly oxidized..

[RhythmDoctor]

Today I was able to trace a wire from the 12v panel through an alternate path to a freshwater pump under the galley. Although there is not enough space to run another wire along this path, I could attach this wire to the master terminals in the panel (i.e., always hot), then tap into it inside the galley cabinet, adding a couple of separate fuses for the two pumps.

Next time I go back to the boat I will need to confirm the gauge, material, and condition of this wire. If it is acceptable I will tap into it as I described above. If not I will replace it with appropriate grade wire. But the good news here is that I have found a potential source of hot wiring already in place without the need to cut more holes in addition to the ones that are already there.

[mitiempo]

So the water pump and bilge pump will be sharing wiring?

[RhythmDoctor]

Originally Posted by mitiempo

So the water pump and bilge pump will be sharing wiring?

Yes, but the chance of both running at the same time is 0.0001%. Remember the limited space, short wire runs, and simple subsystems of a 25' daysailer. The bilge is bone dry (as was every Catalina 250 I saw when shopping). Thanks to the outboard, there are almost no through-hull fittings below the water line. This bilge pump will never come on unless there is a slow leak from above or below while it is docked - which is why I'm installing it. The boat has no hot water, and comes from the factory with only manual pumps for the bilge and for the head and galley. The Shurflo pump is an aftermarket retrofit, and is convenient, but I rarely make use of the massive 12 gallon fresh water reservoir. If anything, I think it's a good idea to have the two using the same 3' run of wire because every time I run the water I am testing them to make sure they have not corroded away.

I know to the purists up here this will come across as reckless endangerment, but given the option of no automatic pump (as with the majority of Catalina 250s out there) and the pump I am proposing, I think I will get good incremental benefit out of this.