Shaft Wipers for Bonding System?

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Taras

Taras

Senior Member
Joined
Jan 11, 2008
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400
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Currently Boatless
Been searching a lot for bonding system propeller shaft "wipers" or "pick ups".
Does anyone know where to find these little buggers?

Thanks for pointing the way.

Taras
 
We had them installed on our boat not long after we bought it, so in the early 2000s. They were installed by the marine electric shop that we use in Bellingham. They are formed of spring steel and loop around the shafts with the replaceable shoe (contact) in the bottom of the loop. The main strap goes upwards and is fastened to a nearby fuel tank frame by a spring that keeps upward tension on shoe against the shaft. Unfortunately I don't know who makes them but it's a common type.
 
Fisheries Supply also carries them.
 
Propeller Shaft Wipers - Galvanic Control Systems - Electrolysis Solutions - Engine Systems - Downwind Marine
is one example.

I installed one years ago from, I think, Newmar.
Some folk make their own. I would now but at the time I just bought one.

Mine is a motor brush, large, brazed to a brass strap. The strap is installed with some preload so the brush presses lightly on the shaft. The strap is then tied electrically to the bonding system.

In fact the brush need not be brazed. Most brushes come with a short copper braid lead which can have a ring terminal added which is then secured to the brass strap or directly to the bonding wire. The brush simply needs to be attached to the strap.


A brush should be readily available from most motor or alternator/starter repair shops

The contact area needs to be cleaned and smoothed but that usually should be easily ensured.

Check periodially that it is keeping contact. They do help.
 
Thank you gents! Appreciate the feedback.
 
Commercial ones sometimes need so much modification to install I just made my own.


The pad needs to be softer than stainless so I used an oldoutboard zinc with a bolt through it so attaching a bonding wire was easy.


But soft copper or tinned wire braid works too.


Though not absolutely needed to keep a shaft and propprotected, a brush is self cleaning as opposed to coupler jumpers and shaftzincs…on my last 2 boats I have installed them and directly connected them tothe transom plate zincs. They have helped noticeably.
 
I think a shaft brush is an excellent way to destroy a prop. At the very least it will help get rid of your shaft zink faster :)
 
I only have about 12" of shaft in contact with salt water so the prop-nut zinc bullet works well and lasts for 18+ months to 1/2 way.

I don't need to add any more metal (engine and raw-water system)to an insulated shaft so no thanks. This would also require adding zincs to protect the cooling system as I would be connecting the prop and shaft to it.

Have the bonding system analyzed with proper test equipment and by a skilled operator to determine need.
 
I have the silver/ silver chloride cell...and know how to use it.


A brush doesn't do anything more than the normal bonding system does....


Theoretically your shaft and prop ARE bonded if your boat bonding system is set up normally with green bonding tied to black neg DC buss someplace....which often IS the engine block.


Nigel Calder recommends them on page 145 of his second edition Boatowners' Mec/Elect Manual.


My real life experiences and multiple bonding surveys I have done show they do just fine and help when older boats have boding and corrosion issues by providing new and fresh contacts in the bonding.


Sure it may accelerate stray current corrosion....but it doesn't "make it happen" any more than a lot of possibilities. And accelerating it usually wont cause any more damage than will happen eventually anyhow till it is noticed.
 
Last edited:
Agreed with PSN. Brush is likely redundant. To confirm take a digital volt meter and measure volts between shaft and engine block or gearcase. Everytime I've checked a boat it was never more than a mV or two, essentially zero. Now when running, it is possible to get gear output shaft to float on oil film then connection could be lost. But that is a fraction of most boat's time. Not even sure the galvanic corrosion is an issue underway???

On mine I have a shaft zinc and engine bonded to transom zinc, so no need for a brush.
 
psneeld said:
I have the silver/ silver chloride cell...and know how to use it.


A brush doesn't do anything more than the normal bonding system does....


Theoretically your shaft and prop ARE bonded if your boat bonding system is set up normally with green bonding tied to black neg DC buss someplace....which often IS the engine block.


Nigel Calder recommends them on page 145 of his second edition Boatowners' Mec/Elect Manual.


My real life experiences and multiple bonding surveys I have done show they do just fine and help when older boats have boding and corrosion issues by providing new and fresh contacts in the bonding.


Sure it may accelerate stray current corrosion....but it doesn't "make it happen" any more than a lot of possibilities. And accelerating it usually wont cause any more damage than will happen eventually anyhow till it is noticed.
Click to expand...


:thumb:
 
Thank you Blue Yonder for the link. That's exactly what I was looking for!
My engine and shaft have a "coupling" that appears to be some kind of very thick heavy plastic....probably to protect the transmission in case you hit a log or something. Anyway, I need to bond the shaft due to this. Shaft is not electrically connected to the engine.
 
In addition to brushes...maybe even foremost....is many suggest jumper wires from shaft coupling to tranny....even with normally bolted couplings.

Usually heavy copper foil is used like the bonding foil along stringers.
 
If you do get shaft brushes, some of the straps that support the brushes are made of stainless steel. Stainless is only slightly better than a rock for conduction so if you decide to go with the shaft brushes, don't get stainless.
 
Our spring loaded straps are stainless but the wire that connects the wiper to the bonding system is attached at the bottom end to the "shoe" that rides on the shaft and at the upper end to the bonding system. The stainless strap holds the shoe against the underside of the shaft but it does not connect the shoe to the bonding system.
 
corrosion underway? The electrical potential rises with the flow of water over the dissimilar metals. So, faster you go, higher the potential & corrosion.
 
psneeld said:
[/SIZE]They have helped noticeably.
Click to expand...

How are they helping? Shaft zincs last longer? Do you still use shaft zincs?

kulas44 said:
I think a shaft brush is an excellent way to destroy a prop. At the very least it will help get rid of your shaft zink faster :)
Click to expand...

How? By turning your shaft zincs, or if none, props, into a sacrificial anode for the rest of the system? If you have big transom zincs properly bonded, is that possible?
 
My shaft zinc goes a year now instead of 6 months or less.
 
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