Shaft brush for grounding- sources?

the head broke off the strap of the Promariner brush on the 2” prop shaft.

so far, all parts companies that have listed them in the past are “out of stock”.
one source stated that Promariner was sold, and current company Apparently not manufacturing them.

anyone use a different replacement?

Thanks in advance.

I asked a similar question a few months ago. I went with one from ElectroGard.

https://www.suremarineservice.com/Electrical/Replacement-and-Spare-Part/SB-6B.html

Good luck - Peter

mvweebles said:

I asked a similar question a few months ago. I went with one from ElectroGard.

https://www.suremarineservice.com/Electrical/Replacement-and-Spare-Part/SB-6B.html

Good luck - Peter

Click to expand...

Does anyone else have shaft grounding devices?
I had two zincs on each shaft and the Stb zincs would be totally gone in 12 months. My boat yard put three on that side and they now make it 12 months. Would a shaft wiper help.
I haven't done any homework on bonding and zincs.

Geez, that sounds excessive. Our shafts are very long,14 feet. Two aluminum anodes last a year although I usually have them changed every nine months. Our double thick transom diver's dream goes 18 months. Is your boat equipped with a galvanic isolator? It is possible that a boat neighbor is eating your anodes.

fryedaze said:

Does anyone else have shaft grounding devices?
I had two zincs on each shaft and the Stb zincs would be totally gone in 12 months. My boat yard put three on that side and they now make it 12 months. Would a shaft wiper help.
I haven't done any homework on bonding and zincs.

Click to expand...

I do have galvanic isolators but know little about that side of the system[emoji32]. I need to learn how it works and if it is installed right.

You can get a starter brush from a alternator/starter shop and attach it to your spring plate, solder pigtail to your bonding lead.

With a shaft brush, you can include your shaft and prop into the rest of the bonding/anode system. Without a shaft brush, a connection to the main ground through the engine and transmission is unreliable. Anodes placed on the shaft "fix" this problem.


Ken

If you run across a piece of bronze or copper pipe in the 1" ID range, you can cut a one-inch length of it lengthwise to make an adequate "brush."

If you can't find a proper grounding brush, use a braided copper ground strap draped over the shaft with a weight at the bottom to assure good contact with the shaft surface.
https://www.amazon.com/dp/B01M7NP6KH
or buy a roll of bulk woven copper grounding strap and solder one end for the terminal, and put a fishing weight on the other and lay it over the prop shaft.

I use a copper brush, looks like a paint brush. I can usually find one at an industrial supply. Copper doesn't seem to wear the shaft.
Maybe now on Amazon or ebay.

Drilling the end piece to reattach to the spring would work.
They are often just starter brushes brazed onto springy arms. I welding shop might braze it for you.

stubones99 said:

a roll of bulk woven copper grounding strap

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I was tracing my bonding circuit the other day and saw that my shaft brush was okay but the wire that connected to the original woven copper grounding strap had come loose. Tracing the grounding strap about a foot I saw that it was completely broken as it went aft to my 2 "Diver's Dream" zincs on the stern. In fact, I found another break in the grounding strap in the lazarette. No wonder my zincs last so long.

In getting ready to fix it, I'm wondering "why woven copper for a grounding strap?" Mine is all green and crusty and I wouldn't trust a connection even if it were possible to mend. Why not insulated tinned copper wire? My original connections are just crimp ring connectors with a SS screw through the strap. Quick and cheap, but it seems like there could be a better way. Maybe 6 gauge solid copper grounding wire ($35 for 50') with the branch wires soldered to it?

@Marco Flamingo #12

ABYC E-2, Cathodic Protection specifically prohibits braid in the cathodic protection system. Self tapping screws are also prohibited.

I recommend installing a common bus at each cluster of underwater metal components and connect these busses with AWG 8 green, tinned boat cable. Make the connections to the busses with adhesive lined, heat shrink ring terminals. At each bus, make whips from the bus to the individual underwater metal component. Do not daisy chain. Connect the individual whip to the component with an adhesive lined, heat shrink ring terminal. Spray the connection with CRC HD Corrosion Protection or equivalent. Note: Each connection to the bonding system should have a resistance < 1.0 ohm.

CharlieJ said:

@Marco Flamingo #12

ABYC E-2, Cathodic Protection specifically prohibits braid in the cathodic protection system. Self tapping screws are also prohibited.

I recommend installing a common bus at each cluster of underwater metal components and connect these busses with AWG 8 green, tinned boat cable. Make the connections to the busses with adhesive lined, heat shrink ring terminals. At each bus, make whips from the bus to the individual underwater metal component. Do not daisy chain. Connect the individual whip to the component with an adhesive lined, heat shrink ring terminal. Spray the connection with CRC HD Corrosion Protection or equivalent. Note: Each connection to the bonding system should have a resistance < 1.0 ohm.

Click to expand...

Does it prohibit braided copper or braided tinned copper?

Copper Braid is nice when you have frequent movement since the strands are hairlike and take a while to work harden and fatigue. I assume the reason they prohibit braid is that it could de-zinc-ify with salt water and electricity, leaving a poor ground. I would say that using a braid as a shaft ground wouldn't be a bad idea, since it is unlikely to damage the shaft and is out of any bilge water so should last quite a while.

I don't like those connections on the bottom isolator. At the least, they be be loosened and straightened out to relive the strain at the ring connectors. Better yet, new heat-shrink connectors should be installed to eliminate the exposed wire which invites corrosion.

fryedaze said:

I do have galvanic isolators but know little about that side of the system[emoji32]. I need to learn how it works and if it is installed right.View attachment 111099

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catalinajack said:

I don't like those connections on the bottom isolator. At the least, they be be loosened and straightened out to relive the strain at the ring connectors. Better yet, new heat-shrink connectors should be installed to eliminate the exposed wire which invites corrosion.

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I agree John. Those lugs are poor. I wish I had a critical eye for that stuff. Good thing is, that isolator has been there for 15 years and is in a very dry clean area.

@stubones99 #14

The prohibition is against braid-no differentiation between tinned or untuned.

I fabricated this setup. Looking for a critique. I wrapped copper braid around the end. It is about 6 layers. I measured for continuity and resistance to the ships bonding strip and it is very good.

It looks good. To be effective, the resistance should be as close to 1 ohm (or below) as possible. Unfortunately, with untinned braid it will corrode quickly *all through the braid*. After the corrosion starts, the resistance will start to rise.

Ken

kchace said:

It looks good. To be effective, the resistance should be as close to 1 ohm (or below) as possible. Unfortunately, with untinned braid it will corrode quickly *all through the braid*. After the corrosion starts, the resistance will start to rise.

Ken

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Thanks, I will follow up after several months with readings and pics.

fryedaze said:

Thanks, I will follow up after several months with readings and pics.

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Yeah I was thinking about it and maybe a spray of mid-weight corrosion protection would be enough to keep it from corroding but still allow good metal to metal contact? It certainly might and you could measure it to confirm.

Ken

Just put some conductive grease in the braid. That will exclude air and salt and make it more conductive... I've seen a ground strap laid over a rotating shaft with a lead weight on the free end last for years, and not score the shaft. Simple but effective.

stubones99 said:

Just put some conductive grease in the braid. That will exclude air and salt and make it more conductive... I've seen a ground strap laid over a rotating shaft with a lead weight on the free end last for years, and not score the shaft. Simple but effective.

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Done, thanks

My memory is that, although ABYC defines a conductor, in general, as anything able to carry a current, the phrase "bonding conductor" is used specially in ABYC E-2 to describe only those conductors intended to distribute cathodic protection among the bonded components.

My understanding is that interfacing hardware isn't considered a "bonding conductors", but instead a means of attaching bonding conductors

My understanding is that brushes, slip rings, wipers, etc, are a type of interfacing hardware known under the standard as "shaft contactors".

My understanding is that the prohibition against braided copper in E-2 covers only "bonding conductors", and not "shaft contactors".

In other words, my belief is that ABYC E-2 no more prohibits shaft brushes, or any other type of shaft contactor, from being made from braided copper than it requires them to be made of exactly (a) at least #8 AWG tinned, stranded copper wire or (b) at least 1/32"x1/2" copper strip (and possible, thicker, depending). And, there ain't no such thing as a brush made of either.

I'm not sure how ABYC defines a brush, but assuming ABYC defines in a way that would include one made of braid, my memory is that ABYC E-2 does require that a brush not score the shaft.

Having said all of that, I'm not sure that I like the idea of a weighted braid over the shaft. And, I'm not sure that a professional electrician would consider it to be good tradesmanship. And, I'm not sure that something somewhere doesn't prohibit it.

But, I don't think it is the referenced section of ABYC E-2, which applies only to "bonding conductors", because, well, if nothing else, shaft brushes and slip rings are proof by example that it does not.

If I had to guess at a rationale for this it is that brushes and other "shaft contactors" are considered isolated mechanically wearable items subject to inspection and replacement as needed, whereas the "bonding conductors" are considered a major, if not the major, part of the cathodic protection system, are much harder to /fully/ inspect and service, and are intended to be permanent parts of the system.

fryedaze said:

I fabricated this setup. Looking for a critique. I wrapped copper braid around the end. It is about 6 layers. I measured for continuity and resistance to the ships bonding strip and it is very good. View attachment 115372View attachment 115373View attachment 115374

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Don't try this at home kids!. The copper braid is an epic fail. It wore through in 800 miles. Maybe too much pressure on the support to shaft. Going to try a piece of bronze pipe cut in half. Live and learn.

An alternative is to take a block of graphite and make a groove in it to fit the shape of the driveshaft, and mount the graphite block to your arm. The graphite is slippery and won't score the shaft but is a good conductor. How to secure the graphite to your arm? Epoxy? Bolts?
https://www.ebay.com/itm/283951683631

The copper / bronze braid I saw in the past were simply draped over the shaft, with a weight at the free end, and the other end of the braid grounded. They lasted for years on industrial pumps.

@stikman: What is your goal in installing a shaft brush? kchace in post #7 nailed it: If you have anodes on your propulsion shafts, than the shafts and propellers will be cathodically protected if the anodes are sized, installed and maintained correctly.

A shaft brush distributes some of the cathodic protection current created by the shaft anodes to the boat's bonding system. Why would you want to do that? A properly installed bonding system that includes a diver's friend plate anode or anodes on the transom will protect all underwater metal bits connected to the bonding system with connections that have < 1 ohm of resistance.

The only time I have prescribed a shaft wiper (Electroguard) was on a Lazzara that had so little exposed shaft that adequately sized shaft anodes could not be installed. In this case, I distributed the cathodic protection generated by the plate anodes to protect the shafts and props by using a high quality shaft brush system.

CharlieJ said:

@stikman: What is your goal in installing a shaft brush? kchace in post #7 nailed it: If you have anodes on your propulsion shafts, than the shafts and propellers will be cathodically protected if the anodes are sized, installed and maintained correctly.

A shaft brush distributes some of the cathodic protection current created by the shaft anodes to the boat's bonding system. Why would you want to do that? A properly installed bonding system that includes a diver's friend plate anode or anodes on the transom will protect all underwater metal bits connected to the bonding system with connections that have < 1 ohm of resistance.

The only time I have prescribed a shaft wiper (Electroguard) was on a Lazzara that had so little exposed shaft that adequately sized shaft anodes could not be installed. In this case, I distributed the cathodic protection generated by the plate anodes to protect the shafts and props by using a high quality shaft brush system.

Click to expand...

Back to the original post: I eat my stb shaft zincs in one year. My stb transom zinc never gets reduced. I am bandaiding a problem.

@gkesden #24

My memory is that, although ABYC defines a conductor, in general, as anything able to carry a current, the phrase "bonding conductor" is used specially in ABYC E-2 to describe only those conductors intended to distribute cathodic protection among the bonded components...In other words, my belief is that ABYC E-2 no more prohibits shaft brushes, or any other type of shaft contactor, from being made from braided copper..

Click to expand...

Braid is not allowed because it deteriorates so quickly in the harsh environment that it is used in. Using braid as the contact element between the bonding system and the propulsion shaft certainly violates the intent of ABYC E-2.

@frydaze #28
The transom anode is the core of the cathodic protection system that protects all the underwater metal that is included in the bonding system.

The propulsion shaft anode/anodes form the core of the cathodic protection system that protects the propulsion shaft and propeller.

Trying to cross connect one to the other is very difficult to do effectively. Shaft "brushes" have been shown to be not very effective. The most effective manner is a machined collar with a silver plate contact area and multiple brushes that will provide the cross connection with a low resistance that is needed to pass the 1A of cathodic protection current created by an aluminum or zinc anode. See the Electroguard website.

BTW, aluminum anodes provide about 50mVDC more potential, can be used in salt, fresh or brackish water, provide 50% more service life than an equivalently sized zinc anode, cost the same or are cheaper than zinc anodes, and they don't have the heavy metal cadmium in them that sloughs off of zinc anodes and makes its way up the food chain into us. Recommend you switch to Al anodes.

Regarding testing your galvanic isolators.
Barring any technical documentation with specific test information; test them by disconnecting the safety ground wires and use a digital multimeter in the diode test function with the positive probe on one of the GI studs and the negative probe on the other stud. The reading on the meter will slowly rise (if the GI has a parallel capacitor) and will stabilize. Switch the leads and retest. If the two meter readings are within 10% of each other the GI is working.