Wiring Anxiety

[Joe Myerson]

Sorry for this long entry, but I need some wiring advice

Crème Brûlée remains on the hard, because I'm waiting for the arrival of my new Pelagic autopilot. Since these devices are built to order and facing some parts shortages, mine is scheduled to arrive soon after Memorial Day. I've studied the installation instructions, and I'm somewhat concerned over my competence to wire the autopilot successfully.

My biggest worry is how to ground the unit correctly.

If I read the instructions accurately, the autopilot should be wired through the panel. Unfortunately, all the connections on my 25D's small panel appear to be full. I wired some devices, like my VHF radio and chart plotter, directly to the battery bank. Both have in-line fuses and they work just fine. But my old Raymarine ST2000, which was also wired directly to the battery bank, encountered grounding problems.

Yesterday I tried to remove the wiring panel, but after I removed the screws and tried to pull it off, I realized it was held tightly in place by the wires inside. Is it safe to pull hard? Do I need to cut off and replace most of the existing wires?

And If I do open the panel, is there any way to add another circuit? Is there a grounding bar (bus bar?) in side the panel?

As an aside, I've thought about using the wiring for my existing speed log. The unit, an original-equipment Signet Marine unit, hasn't worked for years. Instead, I use the SOG reading from my GPS/Chartplotter.

Any advice or suggestions would be appreciated.

Thanks and fair winds to all!

--Joe

[tjr818]

It might be a good time to add an second panel,something like this: https://www.bluesea.com/products/4321/W ... SB_Charger

That way you could get those connections off of the batter and onto a proper panel.

[Skipd]

I had a 25D for a number of years and did some work on the electrical system. The panel is a tight fit, the battery cables tend to hold the panel back when trying to remove it. If I recall, if one lifts the panel up and around it frees the cables and the panel will work its way out. There was a negative bus bar inside behind the panel. It was kind of primitive and I replaced it with a nice Blue Sea bus bar attached to an epoxied piece in a better location inside the panel compartment.
As for extra extra connections, cannot remember exactly how that was handled, but adding another panel or fuse box makes sense. I used space in the port locker in the bulkhead in front of the batteries for some battery management equipment(turned out to be overkill and an ACR would have sufficed). On my current boat (CD30B), very similar to the 25D in layout, I’ve added a sub-panel of 6 +/- fused connections which is connected to the “Nav/Com” breaker. To this sub panel I’ve connected vhf, ais, instruments.
Hope this helps.

Thanks

[Joe Myerson]

That's great advice! I was wondering where to put an extra subpanel. I believe my VHF and chart plotter both specified that they should be connected directly to the batteries, but an extra panel would certainly help.


--Joe

[Steve Laume]

This is what I used on Raven. I have separate USB charging ports in other more convenient places. This may seem like a lot of circuits but they fill up fast. You may find that you want to separate some of your existing components and you already have a couple of items that do not go through the panel. I hate in line fuses as they are far more difficult to check and replace than resetting a breaker. If you are wired, directly to the battery, you don't have a good way or shutting off a circuit.
https://www.defender.com/product3.jsp?n ... &id=838811

When you do pull out your panel you are probably going to find all the grounds going to one of the posts on the volt meter. I would suggest changing this to a buss bar.

Once you open things up, you are going to find what is, basically, a can of worms. There is a lot you could do to improve on the original wiring. If you don't have a good, or even basic, understanding of marine electrical systems, it might be a good idea to start by buying a good book on the subject.

Wire ties are your friends, Steve.

[John Stone]

I was really worried about wiring my boat too. I read some. Got some advice from someone I trusted and plunged in. The buss bar and also terminal strips are essential. The comments about the sub panel are spot on. Take your time. You can do a nice job. Picture of mine attached. Very happy with it.
I think there is so much experience on the board if you start a projects page and post your questions you'll get good advice.

[gates_cliff]

I've got a photo somewhere of the rats nest that is behind my switch panel, I'll find it and post.

I've been considering for some time doing what John's done, although, I know my woodworking skills won't match

[fmueller]

Joe,

I just finished installing a Pelagic AP in Jerezana … works well. Much stronger than the Simrad TP 32 I had.

I used an ap on my iPhone called “Metal Detector” which can tell you where magnetic fields are on your boat. You don’t want the Pelagic controller in any extraneous field. Just by chance my chart plotter had a tiny but very strong small magnet which was in place internally to snap shut a flap that covers the SD card reader slot. I discovered this AFTER installing the Pelagic controller in the same cockpit panel (ignoring the advice to place the controller away from electronics). My initial trial run was a disaster.

I really wanted the controller in that panel. So sheepishly after the fact I downloaded this ap for the phone and discovered this really strong field in my B&G chart plotter. Being the stubborn monkey that I am I disassembled the chart plotter and removed that little magnet and closed the flap with double backed tape.

Some electronic devices do create fields, but many do not, in particular 12 volt devices, because they don’t have a power supply transformer and are strictly DC devices and pretty low current. My chart plotter (now) does not create any field that I can measure. More over the autopilot is working as advertised.

I think the advice to get a breaker in between all your loads and the batteries is the way to go, with the exception of maybe a bilge pump.

[jbenagh]

Joe,
about 10 years ago I installed a ground buss bar. I think I epoxied it in place behind the panel (some sanding involved). Lots of nice ring terminals with shrink tubing and adhesive! I'm so much more comfortable knowing what's going on back there; it was a little scary before. Then a few years ago I installed a terminal strip to allow me to continue adding loads to existing breakers. A big "to do" is swapping to more directed breakers but the electronics industry (pat on my back) has been really good about reducing current needs so I've been able to add AP, radar, upgrade instruments, etc without needing to increase breaker needs in the panel. Only place I added a real breaker was the fridge and that has been wonderful.
I might have some photos from a CD30 if you're interested. I need to hunt them down though.
Jeff

[Keith II]

Hi Joe,

I'm nearly done with a complete rewiring of my 25D, motivated by the rat's nest I found behind the 12v panel and under-sized (by today's standard) battery cables (nothing was wired to current "code"). The highlights include:

- I installed a Blues Seas mini dual-circuit battery switch and ACR thru the bulkhead just above the dish racks (open to the port locker where the batteries are). This keeps all of the new 2AWG battery cables in the locker and engine space (not snaked up into the cabin).
- The 12v panel is now fed by new 6AWG pos and neg from the DCBS and neg bus bar, respectively. All cables/wires now properly fused.
- I removed the original battery selector switch from the 12v panel and modified that space to fit an additional 4 breakers.
- I completely rewired the 12v panel with a new voltmeter and ammeter and led indicators for "main power on" and each individual external light circuit (ie. Nav, Steaming, Anchor, and Foredeck).
- I also installed two 4-fuse blocks for electronics and instruments, a neg bus bar, and a pos terminal block inside the 12v panel space. Tight fit but everything is now organized and the circuits are easily accessed and isolated if needed.

Not a super difficult job, but I did do a fair amount of research and design iterations over the winter. Below are some preliminary photos:

IMG_3170.JPG

IMG_3171.JPG

IMG_3200.JPG

Happy to supply any other info if it will be helpful.

[Joe Myerson]

Jeff and Keith,
Thanks so much for your answers.

Keith:
After opening my original-equipment panel, I realize that I should rewire the boat, the way you did it. Using the existing cut for a breaker panel and relocating the battery selector to the bulkhead between the port cockpit locker and the "kitchen" area makes a lot of sense.

I'm not sure I have time before my scheduled launch to order the required panels. But it's a project well worth pursuing.

Jeff:
If you have any images of your grounding bus bar and terminal block would also be helpful.

Here is a photo of the back of my existing panel (the original installed in 1982):
[img]https://photos.google.com/photo/AF1QipP ... DD2p9q3BU8
[/img]

If I were to continue using this panel for the current season, where would I attach the leads for a sub panel?

Thanks all.

[Cathy Monaghan]

We added the same panel as Steve to our CD32.

This is what I used on Raven. I have separate USB charging ports in other more convenient places. This may seem like a lot of circuits but they fill up fast. You may find that you want to separate some of your existing components and you already have a couple of items that do not go through the panel. I hate in line fuses as they are far more difficult to check and replace than resetting a breaker. If you are wired, directly to the battery, you don't have a good way or shutting off a circuit.
https://www.defender.com/product3.jsp?n ... &id=838811

When you do pull out your panel you are probably going to find all the grounds going to one of the posts on the volt meter. I would suggest changing this to a buss bar.

Once you open things up, you are going to find what is, basically, a can of worms. There is a lot you could do to improve on the original wiring. If you don't have a good, or even basic, understanding of marine electrical systems, it might be a good idea to start by buying a good book on the subject.

Wire ties are your friends, Steve.

[Joe Myerson]

Cathy,
Thanks for reposting Steve's posting.
My Pelagic unit shipped from California yesterday, and they sent me a PDF of the installation manual. It definitely says to power the unit "from a panel."
I'm trying to avoid a rewiring until after the season, but that might not be possible. The simplest short-term solution would be to add a bus bar for the grounds behind the panel, assuming I have one available 15amp circuit on the existing panel.
The old panel isn't as horrible as I feared: no wire nuts--those were mostly in the cabin lights, and I've replaced them.
But there's lots of black tape (the cloth kind) and a great deal of solder. That might have been accepted practice in 1982.

Steve,
I've got several books on 12-volt systems, but some of them are old and heavy on theory rather than how-to instructions.

--Joe

[wikakaru]

As an aside, I've thought about using the wiring for my existing speed log. The unit, an original-equipment Signet Marine unit, hasn't worked for years. Instead, I use the SOG reading from my GPS/Chartplotter.

I'd be surprised if the wiring for a speed/log unit is sized correctly for an autopilot unless the wiring was vastly oversized to begin with. I'm not sure which Signet unit you have, but the SL254, for example, has a rated power draw of 0.20 amps with the light off and 0.27 amps with the light on. From Pelagic's web site, peak current draw of their autopilot is around 8 amps. The autopilot draws 30 times as much current as the speed meter.

Before you install the wiriing, read up on "ampacity" and how to choose the proper wire size for an electrical load. You have to know a few things: the maximum current draw of the device (double-check that 8 amp figure I found); the total length of the circuit, which is the length of the wire used to power the device times two (because there are two wires in that cable, and the electrical circuit runs both out and back); whether or not the wiring will run through an engine room (high temperatures found in the engine room cause more resistance in the wire); and how much loss is acceptable (tables are usually for 3% for "critical" systems or 10% for "non critical" systems. I'd call an autopilot critical. Knowing those 4 things, you can look them up on a chart or use an online calculator like this one: http://circuitwizard.bluesea.com/#. That calculator also takes into account a few extra factors that most tables don't, so it's a good resource.

I don't mean to unnecessarily scare you, but this is a really important thing to get right. Using too small a wire for the job can result in the wire getting too hot and starting a fire. Imagine you go to sea, get caught in a storm with large following seas, and the autopilot starts working harder and for a longer period of time than it ever has. An undersized wire that was just fine when you installed the autopilot and tested it in a short cruise around a flat harbor could critically overheat at the worst possible time. The same goes for any other component of the system that you use: ring or splice connectors, bus bars, switches, fuses, circuit breakers, etc. Make sure they are good quality marine fittings and are installed properly.

I realize that learning all about marine electrical systems before installing a piece of electronics is not nearly as easy as just following a short how-to, but the principles and practices are something that everyone who has a boat with electricity on board needs to know. It literally could save your life.

If you have tried to study the ins and outs of marine electrical systems and just can't fathom it (don't worry, I've met some brilliant people who just can't get their brains to wrap around certain technical topics) then at least make sure you consult with a qualified expert to either verify the details of the installation or to install it for you.

Smooth sailing,

Jim

[Joe Myerson]

Thanks, Jim, and everyone else,

I abandoned the idea of using the speed log connection a while ago, and I've been studying Youtube videos and books by Nigel Calder and others. At the base of it all lies the vague memory of my 10th-grade science class (very, very dated--but volts, watts and ohms haven't changed in the past half-century).

My original 1982-vintage electrical panel, with its soldered connections and miles of cloth electrical tape needs replacing, or at least rewiring, and I should definitely add a sub panel for the autopilot. Right now I want to do as much of this work as I can while the boat is on the hard.

The Pelagic unit arrived on Friday. The instructions are fairly clear. I've been away from the boat util today (Sunday). I'll be taking an inventory of what I've got, trying to label and trace the existing wiring, and seeing if I dan design a better solution. I still hope to avoid a total rewiring, because that would take up most of the sailing season. But we'll see what turns up.

The adventure continues.

--Joe