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Author Topic:   Grounding
floater88 posted 07-04-2014 07:20 PM ET (US)   Profile for floater88   Send Email to floater88  
On my 1988 Revenge 20 W-T, the green ground wire from the water submerged grounding plate goes right to the gas tank. I installed a [MOOR Electronics] Sub Troll Speed and Temp probe on my down rigger and the instructions state that the negative wire has to go to the battery and then the water to complete the circuit. The positive wire from the head unit goes to the Circuit Panel. I have run the negative wire from the Moore unit to the battery and then spliced in a pig tail wire that I plan on soldering to the green wire near the transom. Would this be an issue since this green wire also goes to the gas tank?
jimh posted 07-04-2014 09:58 PM ET (US)     Profile for jimh  Send Email to jimh     
I am not sure I understand the circuitry you are installing, but, as a general rule, the bonding circuit for the fuel system should not be connected to other circuits which might cause some stray current to flow into the fuel system bonding circuit.

When you connect your new accessory to the battery negative, you will be connecting it to the water, as the battery negative is connected to the engine block and other components, and they'll be connected to the water.

floater88 posted 07-05-2014 08:30 AM ET (US)     Profile for floater88  Send Email to floater88     
Thanks for the reply. Is there some kind of isolator I can put between the point where i'm going to attach the ground wire and the gas tank that would keep any stray current from reaching the tank? I've had this [MOOR Electronics] unit in use for two years now and it only works sporadicaly. I reread the manual and noticed that it stressed that you need to complete the negative side of the circuit from battery to water. I thought I might not be getting a good ground return through the motor.
jimh posted 07-05-2014 09:03 AM ET (US)     Profile for jimh  Send Email to jimh     
The typical outboard engine should have several zinc anodes in contact with the water, and these should be bonded directly to the engine block, and thus to the battery negative.

Are the installation instructions for the MOOR Electronics Sub-Troll 900 available on line?

floater88 posted 07-05-2014 09:11 AM ET (US)     Profile for floater88  Send Email to floater88     
I checked their web site and didn't see any. I did a search and some fishing sites claimed to have a scanned PDF copy but it wouldn't open.

As I've alredy gone ahead and spliced a pigtail wire from the [MOOR's] ground wire, before it connects to the battery negative, to the grounding wire n the boat, I'm going to remove this pigtail and reseal that grounding wire. I'm going to remove and clean all metal connections to any wires I can find on the motor and hope this helps get a better ground. Thanks

jimh posted 07-08-2014 10:00 PM ET (US)     Profile for jimh  Send Email to jimh     
From browsing the MOOR (not Moore) website, it looks to me like the radio link between the underwater sender and the boat receiver is intended to be aided by some sort of conduction along the downrigger line or perhaps the fishing pole line. MOOR shows an illustration with a pick-up lead or antenna wound around the fishing line or downrigger line.

In terms of a radio circuit that is coupled into the water, the paint on the outboard engines is not a big deal. The MOOR device probably does not need to have a DC connection to the water. Being connected to the painted engine gear case in the water ought to be as effective at radio frequency as if there were no paint on the gear case--I think. Radio signals are alternating current, not direct current, and they flow through capacitively coupled circuit elements with ease. Perhaps you can run that by tech support at MOOR (not Moore) Electronics.

floater88 posted 07-09-2014 06:18 AM ET (US)     Profile for floater88  Send Email to floater88     
THanks Jimh. I ended up Removing the Moor from the front at the wheel and mounting it to the Downrigger Bar at the back of the boat. I now have a 3 foot connection to power and a 3 foot connection to the antennae. The RG6 (?) cables had corrosion at the ends where I had put the cable connectors. I shortned every thing and cleaned it all up. Gonna take it out for a test run today. Those instructions were so amament about continuing the neg wire from battery to grounding electrode. I contacted Moor and they said they couldn't say without seeing my boat in person!!
floater88 posted 07-09-2014 01:54 PM ET (US)     Profile for floater88  Send Email to floater88     
Here is a couple of pics of the installation from their manual.

You will notice how they stress that you need to ground the negative wire to the water beyond the battery terminal. If I shouldn't use the grounding electrode that grounds the gas tank could I just ground it to one of the screws on the transducer bracket? Or attach another screw below the water line?

Jerry Townsend posted 07-10-2014 03:58 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
In general, you don't want multiple grounds - as a "ground-loop" can result - and which will cause erroneous indications with interconnected circuits. What happens in that case, there is an electical circuit, albeit low voltage, between the interconnected electrical equipment and each ground connection and the "connection" between the two grounds. This situation causes major problems in big, complicated systems - and also smaller ones, like our electronics on our boats.

Just use the battery as the one common ground for all equipment and as JimH pointed out, the engine is grounded to the battery and is also in contact with the the water. ---- Jerry/Idaho

floater88 posted 07-10-2014 04:54 PM ET (US)     Profile for floater88  Send Email to floater88     
Thanks guys. I gave up and bought new antennaes with RCA connectors. Hooked it all up and got signal in a bucket of water. Will test on the lake friday and post back. Thanks
floater88 posted 07-11-2014 06:01 PM ET (US)     Profile for floater88  Send Email to floater88     
All is good now. New power cables and antennae did the trick. This unit has cost more in parts then original purchase price. Don't recommend to anyone needing speed and temp at the ball for down rigging.

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