Grounding to Shaft

[Baba Buoy]

A previous owner had connected grounding wires from several stainless steel water tanks, bronze through hulls and a steel diesel tank to the old engine. My new engine came with a shaft coupler that electrically isolates shaft from engine. The instruction manual for the shaft coupler said a wire connection bypass is available to ground the engine to the ocean. Do I need this for my setup?

[a64pilot]

I would say yes because it likely the only zincs you have are connected to the driveshaft / prop and to continue to protect your thru hulls you need a zinc.
Or you could disconnect all the thru hulls and isolate them, or add a zinc outside of the hull but in the electrical circuit with the thru hulls

I'd just add the jumper cause what you have has worked for how many years? Why change it?

[model 10]

Do boats usually ground their entire boat through just the prop zink? I couldn't get the jumper to last in our boat, it broke. I ended up using a grounded brush that rubs on the shaft.

[a64pilot]

Originally Posted by Guy

Do boats usually ground their entire boat through just the prop zink? I couldn't get the jumper to last in our boat, it broke. I ended up using a grounded brush that rubs on the shaft.

I don't know of any other zincs on the average boat.
However many boats float if that is the word their thru hulls etc. and do not bond them to anything.
On mine it seems everything is bonded, even the rigging, I have been told it's part of the lightning protection scheme, maybe who knows.
Only zinc I have is prop zinc and I think that is common, although I often hang a guppie zinc, but most do not.

[GordMay]

Shaft Grounding Strap ➥ https://www.marineprotectionsystems....rounding-strap

[model 10]

Originally Posted by GordMay

Shaft Grounding Strap ➥ https://www.marineprotectionsystems....rounding-strap

I'm not sure what $AU207 comes too in US, but I looked at one of those at the store and saw that I could make it for about $5. A bronze bushing cut in half, a strip of stainless steel and a piece of wire.
My viewing experience in boat yards is, most cruising boats have an external zinc on the hull.

[Baba Buoy]

Thanks for the input. Made my own jumper for now. See attached pic.

[a64pilot]

That will work, however a strap will be more flexible and less likely to fatigue over time.
https://vetco.net/products/braided-g...FVQlgQod-ckEUA

[senormechanico]

Which engine is this?
My Volvo MD2020 has an insulating system between transmission and engine.
The manual specifically advises against allowing electrical connections between the two via shaft bonding because of the aluminum water cooled transmission case.
I bonded my thruhulls but have a shaft saver disc between shaft and transmission.
( I typed tranny, but you can't say that anymore ! LOL, or is it GRRR ! )

[Baba Buoy]

My new engine is a Beta 38. I will test trannie case with magnet. I think it's cast iron.