Wire schematic help

[MDCrappie]

I have personally never seen a electric start outboard motor installed with isolation hardware that would prevent, grounding the hull through the motor.

Funny thing is that I've seen (and read) of guys putting the rubber isolators and gobbing silicone sealer all over the bolts in an attempt to prevent the grounding as they have been given (what I think is) bad information.

Edit to add - My Starcraft originally had one of those rubber (anti-vibration I think) pads over the transom and it is a on 25hp, not thru bolted. I have a 16ga wire from the hull to the negative of battery. It wasn't till I installed a newer depthfinder and realized the interferance I was getting was from a ground issue. Putting that wire on completely stopped it.

 

[InSaneFisherMan]

Thanks. I'll drag out the ohm meter tomorrow (it is an old cheap analog model). My outboard is bolted to the transom (metal to metal). No isolation that I can see.

I learn a lot in these discussions. Unfortunately, you guys are subjected to my dumb questions. Lol.

Using my cheap ohm meter.

Here are a couple of videos, one is checking the (-) to hull for continuity, with boat motor (-) and all (+) connections connected to battery : reading 6.6 ohms. The other video is checking for 12v from (+) to hull, with all connections connected : 12.59vdc.

Both checks indicate that my battery, (-) is connected to hull through the motor.

Checked the set up manual, and no reference to the motor be grounded to the hull or not.

 

[LDUBS]

Using my cheap ohm meter.

Here are a couple of videos, one is checking the (-) to hull for continuity, with boat motor (-) and all (+) connections connected to battery : reading 6.6 ohms. The other video is checking for 12v from (+) to hull, with all connections connected : 12.59vdc.

Both checks indicate that my battery, (-) is connected to hull through the motor.

Checked the set up manual, and no reference to the motor be grounded to the hull or not.

Thanks for sharing this. I attempted to do this with my analog multimeter. Resistance is zero ohms. I couldn't really read the voltage scale other than it is somewhere over 10 and less than 15. Even with operator error it is pretty clear that my battery is also connected to the hull via the motor.

Battery negative is connected directly the engine block.

Might have to put a digital multimeter on my wish list.

 

[InSaneFisherMan]

Thanks for sharing this. I attempted to do this with my analog multimeter. Resistance is zero ohms. I couldn't really read the voltage scale other than it is somewhere over 10 and less than 15. Even with operator error it is pretty clear that my battery is also connected to the hull via the motor.

Battery negative is connected directly the engine block.

Might have to put a digital multimeter on my wish list.

Yes definitely, your hull is tied to (-) of battery and probably most outboards with electric start, bolted to transom on tin boats.

To get back to your original question, you don't need to ground your battery to hull, because it is already done.