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Wiring problem

Jan 28, 2017
Catalina 30 Mk II Williamsburg
I recently removed the tachometer from my 89 Cat 30 for testing. When I returned to the boat I found that my bilge pump and other accessories were not working. Further investigation showed that disconnecting the tachometer had broken the ground circuit for the main distribution board. Before I started rewiring the ground circuit I wondered if anybody else has had this experience. Is this the way Catalina built the boat or has somebody rigged it? When I replaced the trailer plugs i noticed 2 extra wires.
May 7, 2011
Catalina 30 3573 Lake Norman
Need more precise info in order to help you.
What do you mean ‘main distribution board’; what wires were on the tach, which posts; what do you mean “rewire” the ground (negative), removing a tach doesn’t require rewiring; what extra wires, color, which end of the harness; pics; ALWAYS take pics before disturbing wiring/components. Post answers on the official C30 forum and I’ll be glad to take an in-depth look.

(No apologies for being a broken record but the widest resource for C30 issues is to post questions on the IC30A forum.)
Feb 26, 2004
Catalina 34 224 Maple Bay, BC, Canada
Benny, many of us provide links to other helpful information, and sometimes a wider audience is viable for some boat specific information, IN ADDITION to the fine material and contributors here.
Heck, if nobody linked to Maine Sail's website, we'd all still be in the dark! (pi!:):):))
And I very often send folks on those other websites here, promoting sbo. Works both ways.
Jan 28, 2017
Catalina 30 Mk II Williamsburg
The tach was wired per plan. Ground, ignition, send and a connection for the light .I did take a picture before I removed the unit. That's not the problem. I was surprised that removing the ground wire from the tach effects the bilge pump and all the DC accessories fed through the electrical panel. The "extra wires" that don't run through the plug are a second black wire and a second orange wire that I have yet to trace. These attach elsewhere in the captains control panel.
May 7, 2011
Catalina 30 3573 Lake Norman

The distribution panel negative is direct to the batteries and the bilge, etc., negatives are run back direct to the panel (unless the PO did something very odd.) (for instance I ran a #8 "boat negative" that I tied those things into.) But the tach negative is thru the harness #10 black wire to engine ground, nothing to do with the panel. Again this all presumes that there's no "PO Job" done to the boat and that you have a good connection at the battery negative cable (bolted to the bell housing -- which should be relocated from there to a starter bolt.)

If you have the Westerbeke Captain's Panel then bets are off, it had some extra cabling for alarms and I'm not sure if it originally had an ammeter or voltmeter. The orange may have been an Alt out wire to an ammeter.
Just FYI, my tach signal wire was orange, not gray as most are.

The extra black may be (1) negative for the blower behind the panel, or to the diesel lift pump.

Oftentimes I use the pos and neg post on the tach as a "bus" to distribute to the gauges because it is heavier and handy to get to, and out of the way of the panel mess. But even so disconnecting that neg should in no way affect the bilge pump, etc.

Oct 22, 2014
CAL 35 Cruiser Portland OR, moored EVERETT WA
It should come as no surprise that sometimes the boat wiring is not what it seems.

Not every boat owner will get on the forum, ask a question and follow the suggestions. It must be rare, but sometimes folk just do things to their boat. It works and they move on.

Only when you make a change do you discover stuff that you wonder about.
One of the fun elements of owning a "new to you" boat.
Jan 28, 2017
Catalina 30 Mk II Williamsburg
Thanks . I am pretty sure this was a rig by a PO. I need to trace the second black wire from the panel back. The ground at the flywheel is strong but the way it is currently the neg travels from the battery to the ground on the engine to the captain's panel to the distribution panel. When I detatch either the black wire from the harness #10 or the mystery black wire from the captain's panel the main distribution panel looses power. I will work on it and let you know what I find.
May 20, 2016
Catalina 36 MK1 Everett, WA
If all or even quite a few devices used the ground at the tach it’s a wonder the wire didn’t turn into a candle.
Jan 28, 2017
Catalina 30 Mk II Williamsburg
Yes. Reason for concern for certain. I am looking for a schematic that shows where the negative feed to the distribution panel originates. It certainly should not be at the captain's panel .
Nov 7, 2011
Catalina 30 Mk II Barnegat, NJ
Look behind the distribution panel for a gathering place for the load negative wires, probably a busbar of some type. When you find it run a new wire to the battery negative.
No need to pull back the suspect ground wire from the engine panel unless you just want to clean up the wiring.
A schematic probably won’t help since the PO has already made “improvements” to the wiring.