Newbie Yacht Re-Wire HELLLPPPPPPPPPP

[737guru]

I have my 24' Yacht. It has old out of date wiring which is deffinitly in need of up grade. I am going to rewire but have found myself bewildered by the sheer choice of hardware and advice out there and at the moment if I did attempt this I'd really be stabbing around in the dark.

The components I have now are:-

2 Batts, Linked by a 1/2/both heavy switch.
Nav Instruments
Auto Helm
Nav Lights
Cig lighter socket
Radio
Fwd and aft internal lights

I would like the new system to be entirely 12v. It should be possible to charge (both batts at once) by the engine alternator or by shore power which is 240 v 50 hz.

I have an idea of the various components out there which will do all this. But what I don't have is the experience of having done this before! So what I am asking for is your opinion of what components to use in what combination to achive a reliable and expandable system whilst optimising the use of components to keep the budget realistic. My ideal response would come with a scematic so I can start to build my own from it.

Some other info you may want is:-

Engine is a Yanmar single cyl diesel 9HP (starter motor load?)
lighting is four halogen 10w 12v bulbs
Batts are 12ft away from engine and proposed switch panel location.

Specific q's I have are

Is there a "box" out there that has a 12v alternator and 240v shore power input with two isolated batt bank out puts?

What are the best switch panels to use and is there one which incorporates a battery monitor in it?

Thanks very much in advance.

737guru.

[PAR]

This is a relatively simple system for an experienced electrician, but it would appear you're in a little over your head.

You have a few choices, muddle through it the best you can, hire an electrician or gain some education. I'd start with the book "The 12 Volt Bible for Boats" by Brotherton/Sherman. This is available at the book store on this site.

[marshmat]

I like the third option suggested by our friend PAR.

Muddling through is likely to result in something over budget that looks like a rat's nest and blows fuses (or, worse, energizes metal fittings on board without blowing fuses).

Hiring an electrician is easy, but expensive and no fun.

Sitting down for a week or so with some good books strikes me as the place to start. Being trained as an engineer, I could probably rhyme off a bunch of 900-page textbooks that none of us ever actually bothered to read. But there's plenty of more accessible, less mathematical stuff out there, that is actually interesting to read and is actually useful. I've heard good things about Nigel Calder's "Boatowner's Mechanical and Electrical Manual" but have not found a copy for myself yet.

Shorepower is a potentially dangerous game that will require a fair bit of additional reading above and beyond what you need to build a good 12V system. (While a bad 12V system might give people mild shocks and galvanically erode your propeller, a bad shorepower system might dissolve your running gear, set the dock on fire, or kill people who swim too close to the hull. So an extra level of caution is called for here. It's not hard to do it right, but there are a lot of ways to do it wrong.)

[Landlubber]

Nigel Calders "The Boatowners Electrical and Machanical Manual" should be read by every boat owner, like our freind PAR, Nigel is one of those fellas that you can rely on to tell it how it is. Many boat builders (like myself), have ideas and ways of doing what we do, but few get it right always, some of us may disagree with the process, or the application, but it is not "wrong", it is still a recognised method of doing things correctly. Nigel has that ability, so go buy the book, ne needs the money too poor fella, he is building a new boat.

[mydauphin]

Nigels books are great, He must owes me a free lunch by now. I have bought all his books... Anyway on wiring - have a "professional" do it for you, but read Nigel book and make sure he does it right and that you understand it perfectly. It will save you a lot of grief and money later.

[FAST FRED]

It is very poor engineering practice to have low voltage DC in the same area as AC power.Especially on the same panel.

Not illegal, just a good way to kill someone.

FF

[thudpucker]

While we are on this subject....I dont mean to Hijack this guy's thread, but years ago sombody told me not to put two different voltages down a Conduit.
Is there anything to that?
I dont mean AC and DC, Just DC.

[alan white]

It's not legal in buildings to share conduits or boxes between low and high voltages.
As I read it, the commenter asking for help didn't mention anything beyond 12 volts.
Such a system is dead simple. Each individual circuit has a single wire from panel to devices. The ground for all the devices can be shared. It can be a larger guage wire. It is connected to the ground terminal of each device using as short a wire as is needed to join the larger ground wire.
Sizing of wire should anticipate all circuits being used simultaneously, meaning the larger ground wire should have an amperage rating that is at least as high as all of the individual hot lead wires combined.
Wire size can be confusing. That's because wires are rated in a somewhat arbitrary fashion that anticipates an average run in feet, but in fact a wire run a very short distance can be much smaller than one run a long distance and yet both wires would be subject to about the same voltage drop.
Wire, like water or gas needs to be larger-sized for long runs.
I usually would install 12 ga tinned marine wire for all of the circuits discussed. I know I could use smaller sizes for a GPS or radio that's inches from the panel, but I prefer to stick with one size everywhere as long as the longest run and highest amperage device will be adaquately served by that wire size. wire is relatively cheap for what it does.
If you haven't wired before, you can at least begin by running the wires and labelling them. I like to solder all connections rather than crimping them. Connections to a common ground require baring a short (1/4") portion of the larger wire and soldering the smaller wire to it, and then properly wrapping the connection with rubber (not vinyl) electrician's tape.
At the panel, allow extra wire. Use as many different colors as possible. Ground can be black. The battery (battery main switch) side of the fuse panel is one single (red) connection between battery switch and fuses and the circuit side of the fuse panel is where each individual circuit feed is connected. The main (common) ground wire connects directly to the battery switch.

[thudpucker]

Thanks I wasn't meaning to make a point, just ask a related question.
In a boat the guy might have 12Vdc in a conduit along with his speaker wires which might be nearly any voltage.

I took a NASA Soldering course some years ago. He mentiond a couple of good reasons for Crimping wire terminal ends instead of soldering.

[alan white]

What reasons?

[PAR]

Corrosion and movement fatigue are common in soldered connections. Done properly, preferably with the adhesive lined heat shrink, crimped connections survive longer. Many will suggests that strain relief is sufficient for soldered connections, but this doesn't address the corrosion issue and even if the strain relief is very close to the connection, vibration will eventually get at the soldered joint, as anyone with a diesel or full plane powerboat can attest. All the major manufactures have switched to crimps, from their previous custom of soldering and it's also the recommendation of the ABYS and Lloyds.

[CDK]

Thanks I wasn't meaning to make a point, just ask a related question.
In a boat the guy might have 12Vdc in a conduit along with his speaker wires which might be nearly any voltage.

I took a NASA Soldering course some years ago. He mentiond a couple of good reasons for Crimping wire terminal ends instead of soldering.

Boat wiring should not be compared with home installations. There are all sorts of signals, voltages and currents, ranging from antenna signals in the millivolt range to the large 200 Khz spikes for the depth sounder. Absolutely no need to keep these away from each other as long as the proper cables or wires are used. AC should best be transported by a 2 or 3 lead cable, DC by separate wires of sufficient size.
My radar antenna is connected to the display unit with a single 22 wire cable that carries power, control voltages, video signals etc. Some are shielded, some are twisted, the power leads are straight black and red. No problem as long as you know how to do it.

Looking at the original post, my advice is to find someone who is capable to do the installation without asking help from a forum. I could do it with my eyes closed, but a friend of mine who is a retired veterinarian has already asked me a thousand questions and still does not have his wiring 100%.

As to soldering versus crimp:
Crimp connections are cheap and fairly reliable, that is why the industry uses them. If you use terminals from AMP or Molex and the proper, expensive tools they can even be quite good. Crimp a terminal to a wire, grip the terminal in a vise and pull the wire. If you did it right, the wire should break behind the terminal; if the wire is pulled out the quality is not sufficient.

Serious manufacturers first use acid free solder to tin the leads, then crimp the terminal on the wire. You can also reverse the order.
That way your connection is mechanically sound and protected against capillary action, which is the main enemy of marine wiring.

[alan white]

Thanks for the info. I've done both soldering and crimping successfully, but my experience has been on sailboats that don't have much vibration. the corrosion issue is another thing, and I suspect internal cabin wiring is not the same as masthead terminals, etc..

[thudpucker]

Soldering (NASA)
They found most 'field' repairs were done with the wrong kind of solder, and the heat was often excessive.

Any terminal solderd at a factory is probably dipped in the right solder at the right temp. Good stuff always.

Vibration is the worst problem with solderd wires. If the wire is cooked or the Solder the wrong mix, the wire will eventually lose strands to vibration.

On crimping. A factory (Several factory's) had to put out Service bullitens on incorrect crimps. It seems the wire was fed into the crimper too far. The insulation was crimped onto the terminal.

Not all wire lends itself to soldering. Some have too much Stainless in the mix and must be crimped.
Some teriminalends are similar, and wont solder very well.

Having repeated all that from the experts, I still solder some stuff.

[alan white]

Yes, I imagine that technique is as important to success as anything else. A very well made solder connection would be superior to a poorly made crimp, while both methods if well executed will last.
I think stiffening the point where the wire meets the terminal (either by tape or a plastic sleeve or shrink insulator) goes a long way toward preventing strands breaking by fatigue in areas that are open. Engine compartments in particular often have wires breaking at the point of connection to the terminal.

[Ilan Voyager]

I stay old school and I weld, but with some precautions:

1/ I use only first class electronic tin and a electric solder adapted to the size of the wire. Never a gas solder.
2/ I never solder the connection directly in a T. I bend the wire to be connected at right angle, I glue it to the other cable (a drop of cyano) and I solder after so the electric junction has no stress nor vibration.
3/ I seal with a light coat of high temp silicone.
4/ I finish with a butyl tape (3M works well) slightly heated to 45 celsius degrees, so I get a tighter seal.
Sometimes I use a piece of clear silicone tubing and I fill it with a high temp silicone.
Wires are never allowed to move in the boat, being tightly braced, always protected by a piece of rubber pipe, but I leave always a little extra at each junction so the wire can expand, retract and vibrate without stressing (a bit like on hydraulic tubing) the connection.

I'm very cautious with AC 120 or 240 and sea water so I make a sealed special panel and extra insulation precautions. The quality of the wire plastic insulation is crucial. Some, after a while, can become porous and leak electricity. I tend to make electric circuits theoretically able to work underwater.

For the colors I stay with the most common code. Green or yellow striped green for earth, and white for the negative, so I know that any different color is a live (positive) wire.

As I do love the ingenuity of the conception of breakers, I have the idiosyncrasy to use a lot of them and as close as possible to the electronic device to protect. When possible I prefer 24 volts, first because of ohm's law, second as I can feed the 12 volt electronic devices through a regulator.

Never had an electric problem, even with the worst vibrating diesels. But there are other good ways and I'm not writing the law on stone.

And as many have said already, a good book about boat's electricity is a must. Finally it's something simple but that must be done with great care. It's the place for an amateur as he can take the extra care that can´t be done by a professional electrician simply because it would be too expensive, and time consuming.

[CDK]

For the colors I stay with the most common code. Green or yellow striped green for earth, and white for the negative, so I know that any different color is a live (positive) wire.


Unfortunately it isn't that simple.
In low voltage wiring the minus is black, +12V is red. Except when you are French, than it is the other way around.
In AC wiring, most countries use blue for neutral, brown for the live wire and black for a switched live wire. The only one we never expect to carry a voltage is the green/yellow one.

[Ilan Voyager]

True in cars. Not mandatory at my knowledgein boats. There are years I haven't read anything about color codes so surely ISO or another has done a paper on the subject.
The work I missed was house electricity common code. Also as I'm color blind I stay with this code for evident reasons and never use pale and delicate colors but rather contrasted or I'll go in trouble.
How do go your transmission and propellers?

[CDK]

Hello Voyager.
I will write about the results soon, but to give exact figures I need to calibrate the rev. counters first. I did some tests that left me with mixed feelings....

[Ilan Voyager]

Bad luck...sometimes things do not want to work as we hope.

[thudpucker]

I agree with that stiffening. Normally wires break from vibration and corrosion right at the treminal end. Heat shrink is good and strapping the wires down just close to the terminal ends is good too. Those engines move a lot and often and frequently too.

I've re-wired as necessary a lot of instances. On one old boat I pulled a bunch of house wire out. It had been in there for years and was still working good. Solid wire with no problems.

[Landlubber]

thudpucker,

Please don't go there, solid wire on a boat has no place at all, it is in fact not allowed under many society and ABYC rules, this could be misleading to someone trying to do the "right" thing.

[thudpucker]

LOL, OK we wont go back to 1949 and pull up an old abandoned sumpinorother off the muddy bottom of Lake Washington.
I learn everything the hard way. I didnt know Solid wire was a bad thing for years after that.

I've worked on boats with guys and for guys, and the boats were just one PITA after another.
Wiring problems at the Terminal ends were about 60% or more of the intermittent things that made boating such an iffy thing. If you cant count on your boat performance while your out, its just not possible to enjoy the experience.
That wiring is a large part of 'confidence' and solid wires are a large part of Hacking that leads to no-confidence boating.

NO! on solid wires!

[737guru]

Back on thread slightly, does anyone know of a box which takes shore pwr and alternator IN and two batts (house/starting) out? I can see lots of box's, sterling seem to be the best, which do either the shore pwr OR the alternator. I think Ill be going for the sterling 160A A to B Charger, does onyone have experience of these, and do you think the add on digital panel is worth getting?

The rewire has to happen in the next few weeks, I've completed the deisel heater instalation - best thing since sliced bread, I might retro fit a cockpit outlet LOL for up the legs sailing in winter........

The main problem with most the books is that they deal with each system aspect individually, there is not a lot of help when it comes to looking at a system from an intergrated point of view, if anyone has a circuit diagram and pro's con's that would be most helpful, and give me a starting point.

Of course, many many thanks in advance,

737guru.

[marshmat]

Hey 737,

Not sure if you've come across it yet, but Nigel Calder's "Boatowner's Mechanical and Electrical Manual" is pretty good for this sort of thing... including the "integrated point of view" and circuit diagrams you're looking for.

My personal preference would be for double alternators and a totally separate starting circuit- use the piddly little thing that comes with the motor to charge the starting battery and run the engine electrics, and add your own beefy, externally regulated alternator to charge the house bank. If you like, there could be a normally-open switch joining the two in case you need to start the engine from the house bank in an emergency.

With inverter technology where it's at these days, I'd be tempted to run the shorepower directly into a properly isolated, marine rated, high frequency switching battery charger- with nothing else connected to the shorepower side. The boat's AC systems would then run off the inverters. I've seen such chargers available that can handle 40 to 70 Hz at 90 to 280 V, ie. can be plugged in to any shorepower outlet in the world with no electrical compatibility problems.

Of course, the sort of boats I hang around are too small and too simple to have much need for this gear, so for me it's largely an academic exercise while working on ideas for larger craft. Depending on your needs, you may well come up with something very different....

[thudpucker]

In my midget experiences, I liked to keep the Starting battery and starting circuit separate from all that other stuff.