Electrical Concerns

[techie89]

I have a 2005 Yamaha F150 4 stroke outboard that I recently brought in for servicing. The dealer noted a stray voltage that he traced back to the motor. He was reading 386 mV even with the batteries removed. He suspects it is related to the stainless steel prop installed on the motor. The potential was removed by running a ground wire between the engine block and the hull of the boat. It now reads 0 V.

I have a few questions related to this:

1. Should I remove the stainless steel prop and replace it with an aluminum one? Can an aluminum prop be run on these engines as I have heard from different people that you have to run stainless steel?

2. Is this a common thing to have potential created by the outboard? Is it related to the stainless steel prop, and if so what creates it? If it is not the prop, what causes this?

3. The dealer indicated that if left uncorrected, it could cause other electrical problems, shorts, blown fuses, shocks, etc, and possibly corrosion and paint issues. Is this the case or would it require higher potentials than the 386 mV measured?

Thanks

 

[bruceb58]

Re: Electrical Concerns

He detected a voltage potential with the boat out of the water?

What did he bond to at the hull?

What material is your hull.

Does your yamaha have sacrificial anodes on it?

Do you boat in salt water?

 

[techie89]

Re: Electrical Concerns

Yes, it was detected out of water, so I assume it will only be worse when in water. I have purchased a copper sulfate reference probe to perform measurements in the water once I get the dock in.

The hull is aluminum, and they drilled and screwed the wire into the transom area. The anodes are zinc and are in good shape. The boat is used in fresh water....Georgian Bay (Lake Huron).

 

[bruceb58]

Re: Electrical Concerns

My feeling is that you won't have a problem especially considering you are in fresh water. Just watch your anodes. As long as everything is bonded properly, you should be fine.