Wiring question (Rewiring?)

[oldboat1]

I've got a '77 Chris Craft inboard (original single 305) with what seems to be quirky wiring. Last week, the whole electrical system shut down (engine, lights -- everything) while I was warming it up in the slip. I've had a heck of a time figuring out what was wrong -- kept getting a ground short at the fuse panel when testing continuity on the positive side. That problem is apparently the VHF radio. With the radio wiring removed, the short went away. <br /><br />I still don't know for sure whether that takes care of the problem, as I haven't put everything back together yet. But I'm finding that some (maybe all) of the instrument panel switches are wired to both positive and ground. It appears to be the factory wiring scheme, but isn't it preferable to wire light switches (also bilge, etc.) on the positive side? That is, wouldn't there normally be a common ground, with all electronics switched on and off by breaking the positive flow? Fuses are always supposed to be on the postive side -- thinking switches should be set up that way too.<br /><br />could use some thoughts here....

 

[Hooty]

Re: Wiring question (Rewiring?)

Huuummmm,<br />That is different. In other words, all the switches are double poled? I'm sure there was a good reason for that and someone will explain it to us but it sure seems like a hard way to do the job.<br /><br />c/6<br /><br />Hooty

 

[oldboat1]

Re: Wiring question (Rewiring?)

Hi Hooty. Thanks -- It strikes me as strange too. The switches appear to have a postive and (in some cases) multiple negative poles -- black wiring for neg. in my case, and factory numbered tags. The 2-stage switch for running and anchor lights has one positive post, and three negative ones (bow light, anchor light, and stern light), and I think there is a fourth wire in there too. (That's probably one each for the bow and stern lights, and two from the anchor light for the combined anchor/running light function.)<br /><br />I know the macerator pump is hooked up like that too, and maybe more. I know I rewired one of the bilge pumps when I replaced it, putting the switch on the positive side -- figured somebody had wired it wrong, but maybe that's the way it came....<br /><br />Since the wires are numbered, I guess I should be able to find a corresponding negatives and positives, but I'm not sure I want to do that yet.

 

[suzukidave]

Re: Wiring question (Rewiring?)

Oldboat, I think no wiring is weirder than old boat wiring. I suspect it's that way because boat builders love bargains and so make electrical parts fit that weren't necessarily designed for the purpose employed. My 1967 16' boat had nothing but nav lights when it was built, yet it has a fairly heavy duty 20 outlet bus under the dash that serves no real purpose. <br /><br />So maybe Chris-craft bought a truckload of army surplus switches from M48 tanks? I'd figure out what wiring you should have to meet marine code rather than puzzling why they did what they did. If common ground is okay, then you can switch over to it as you go.<br /><br />One possible reason for having a double switch is to ensure a total firewall. That could be a good thing I guess. If the switch throws both wires there's less chance of accidental conductivity somewhere between a positive lead and the common ground (flooded bilge?) frying all your electrical components.

 

[oldboat1]

Re: Wiring question (Rewiring?)

Thanks Suzukidave. Good points. Maybe it finally doesn't make a great deal of practical difference (except maybe in complexity -- running to a common ground on the fuse panel seems simpler.) Today I'm thinking I need to get things up and running for now, and will think about wiring changes later. It took quite a while to find the short, so I hope that will prove to be the problem -- would like to do a little boating.<br /><br />I was thinking too that it would be good to set up a ship's battery for most or all of the stuff unrelated to the starting and ignition system, but the more I see of this boat's wiring system, the more difficult that seems. Maybe that is a winter project.