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  #1   IP: 73.88.73.176
Old 06-13-2017, 12:33 PM
Gubernaculum Gubernaculum is offline
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'75 C&C 33 mk1 factory electrical strangeness

Hello folks,

First of all, thanks for being a part of this very useful community.

My new-to-me '75 C&C 33 with original A-4 has some weird wiring, that I assume is factory, that does not correspond to the wiring diagram in the owners manual. I ran all of my wiring to make my own electrical wiring diagram in preparation for updating some of the boat and systems. I wanted to talk it through with the group to see if anybody thinks I should modify it, or just run it as is.

It mostly pertains to the main grounds.

I have attached a C&C 30 wiring diagram that was made by another member here (thanks!!) - it is mostly the same as my C&C 33 but color coded and much easier to follow.

My main negative terminal block is a single screw with about 10 ring terminals on it. It is located about 1.5 inch from the main positive terminal block, which is unfused, which seems like a recipe for disaster - I am replacing the negative with a big negative bus bar and will move it a little farther away.

1. Fuel level sender ground. My wire goes from the gauge, to the sender, then grounds on the tank itself, then runs to terminate on the motor. The wiring diagram shows it going from the sensor to the terminal block. I could re-route it to the terminal block probably without lengthening the wiring. I believe the fuel tank needs to be grounded both for the gauge to work, and for fire safety. Does it matter whether it grounds on the terminal block or on the motor? In general should all grounds run via the terminal block, or is it OK to have a few things grounded directly to the motor? (I pulled an autopilot ground off the motor, but there is still a bilge pump currently grounded directly to the motor)

2. Wire from Negative terminal block to motor: Does not exist. Should exist based on wiring diagram. Read on.

2. Alternator ground. I have what looks like an original alternator. The alternator generally grounds through the bracket to the motor. It probably still does, but in my case I (also) have a heavy gauge (10g?) black ground wire from the alternator negative, that runs to the engine control panel/gauges in the cockpit and terminates on the fuel gauge negative terminal. This is not shown on any diagram. From that terminal a 10g black runs to the negative terminal block as IS shown in the diagram. There is no wire directly from the negative terminal block to the motor. Therefore, all house current goes through whatever device, to negative terminal block, all the way back to the fuel gauge ground terminal, then to the alternator, which grounds on the motor, which then goes to the battery negative. Seems awful roundabout but works. Would you alter this in any way?
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  #2   IP: 24.152.132.65
Old 06-13-2017, 09:27 PM
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ndutton ndutton is offline
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Quote:
Originally Posted by Gubernaculum View Post
1. I believe the fuel tank needs to be grounded both for the gauge to work, and for fire safety. Does it matter whether it grounds on the terminal block or on the motor? In general should all grounds run via the terminal block, or is it OK to have a few things grounded directly to the motor?
For electrical purposes it doesn't matter, engine block or ground buss. For neatness and presentation, use the ground buss instead of peppering ground wires all over the engine. Of critical importance is a #10 ground wire from the tank to the deck fill plate too.

Quote:
2. Wire from Negative terminal block to motor: Does not exist. Should exist based on wiring diagram.
Yes. Be sure the wire is big enough to handle all the loads simultaneously.

Quote:
3. Alternator ground. Would you alter this in any way (as described)?
Yes. Use the ground going to the instrument panel for panel function only. All other grounds go to the ground buss.
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1977 Catalina 30
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prior boats 1987 Westsail 32, 1970 Catalina 22
Had my hands in a few others
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  #3   IP: 32.211.28.40
Old 06-13-2017, 10:12 PM
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Al Schober Al Schober is offline
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Guber,
Negative terminal blocks don't get fuses. Circuit protection is provided in the positive hot leg (fuses or circuit breakers).
The PO of your boat may have tried to separate the engine/gauge wiring (including grounds) from the house wiring. There was a trend to do this some years ago. Another trend was to isolate ALL wiring from the hull - separate the engine from the shaft, etc. Problem here was with the ground of the VHF antenna, which went to the mast. Get a book on marine wiring that you trust and go from there.
Oh yeah - alternator ground. Don't rely on the foot of the alternator - provide a separate cable from the alternator case to your ground of choice - engine block is easy. My alternator feeds the house bank (overflow to start battery) so a better ground would be the house bank negative.
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Old 06-16-2017, 12:07 PM
Gubernaculum Gubernaculum is offline
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I have Calder and Casey's books, and they have a lot of theory, but they do not go into nuts and bolts or examples of designing schematics. I modified the above diagram to show what is present "as-found" on my boat (but did not update anything from the fuse panel on since it's not the question here). Note the different sides of the ammeter used.

If I add a ground from the negative terminal (soon to be negative bus) to the engine then I make a loop in the circuit. Sounds like the best solution is to remove the ground from the alternator to the instrument panel, and add a ground from the neg bus to the engine, and add a redundant ground from the alt case to the engine.
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Old 06-16-2017, 08:24 PM
sdemore sdemore is offline
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Gubernaculum, I have a question for you. I am trying to put a C&C 30 MK1 project boat back together. I found some bolts coming up through the bottom of the hull, under the fuel tank, with several black wires connected. There is one black wire headed up toward the engine, but cut off before it can reach anything. There is another piece of wire soldered onto the hot section of the exhaust pipe that may have connected to it. Do you have anything like this on your boat? Is there some kind of bonding point or lightning safety thing in the hull?
Thanks,
Steve
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Old 06-16-2017, 08:50 PM
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ndutton ndutton is offline
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If your tank is mounted behind the engine as most are those are probably strut bolts with bond wires attached.
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1977 Catalina 30
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prior boats 1987 Westsail 32, 1970 Catalina 22
Had my hands in a few others
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sdemore (06-16-2017)
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Old 06-17-2017, 09:48 AM
HOTFLASH HOTFLASH is offline
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Wiring Diagram Software

Gubernaculum,

What did you use to draw your wiring diagram? I do not know how easy it was to use, but the outcome is clear and easy to read.

Mary
HotFlash
Tartan 27 Yawl
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Marty Levenson (06-17-2017)
  #8   IP: 73.88.73.176
Old 06-18-2017, 03:38 PM
Gubernaculum Gubernaculum is offline
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I wish I could remember who first put that wiring diagram together so I could give credit where it is due. I found it here on the forum made by another user, then saved it and lost the thread I found it in. I modified it in microsoft paint.
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