Bond aluminum rudder shaft

[Silver_Surfer]

I have a Baltic 43 that I bought that had a lower rudder bearing frozen. Issue was originally the bearing was solimar bearing with a steel cage and rudder stock is aluminum. There was a ground wire on held on to shards by hose clamps. Can’t be stock I wouldn’t think but I not sure this is a good idea. Yard attached it back but I want to figure out why it was done. New bearing is jefe so no metal beside the aluminum race on shaft. Any thoughts?

[a64pilot]

Drill and tap and use a screw, but as hokey as the hose clamp looks, it should work.
Either way I’d put some silicone grease on it to try to cut down on corrosion

[Silver_Surfer]

Originally Posted by a64pilot

Drill and tap and use a screw, but as hokey as the hose clamp looks, it should work.
Either way I’d put some silicone grease on it to try to cut down on corrosion

Thx for the reply. So it’s your advice that the aluminum rudder shaft should be bonded? Meaning if not it will attract stray voltage and deteriorate? I was thinking that the aluminum is a softer metal and would perhaps be a sacrificial if bonded? This bearing issue is common on the boat, another owner told me to look out for the problem and sure enough it was found on by surveyor

[a64pilot]

Two schools of thought, one is bond pretty much nothing under the theory that individual pieces are isolated so they can’t be subjected to stray current.
Another school of thought is to bond everything, then everything is protected by an anode they are all connected to.

Both have followers, I’m in the bond everything camp

[Silver_Surfer]

Originally Posted by a64pilot

Two schools of thought, one is bond pretty much nothing under the theory that individual pieces are isolated so they can’t be subjected to stray current.
Another school of thought is to bond everything, then everything is protected by an anode they are all connected to.

Both have followers, I’m in the bond everything camp

Ck. Thx

[Frankly]

I really think the SS hose clamp is a better way to make the electrical connection. Just need to add a plastic wire tie above the clamp gripping the insulation to eliminate flexing at the bare connection.


Having said that, aluminum is anodic to most of the other marine metals so can become the sacrificial anode. I would have someone that understands underwater corrosion to a look and also figure out where the other end of that wire is connected.


Unconnected may be a safer arrangement.


Frankly

[Breaking Waves]

If the rudder stock has anodes directly attached to it underwater, then that bonding is ok. And personally, with aluminum underwater - It should have an anode.

If it does not have anodes, then you are potentially making the rudder stock an anode for the rest of the boat, especially when you are plugged into shore power in a marina - all the bronze thru-hulls and such, and I personally would leave off the bonding.

There is a way to test this with a silver chloride half cell, which will tell you if the shaft is being protected by the boat's other anodes or not ..... but that only tells you how it is right now, not how it might be if that ground wire corrodes or if you end up parked next to another improperly wired boat in a marina.

also note - Those hose clamps will potentially create corrosion on the stock, right near a pretty highly loaded area of the shaft.

I had an aluminum boat for 15 years.

[RaymondR]

If you do choose to retain the bonding, the wire does not need to be attached in that place, anywhere on metal where there is a good path for electrical current to the rudder stock will do.

[Pete7]

That looks like tinned copper wire touching the rudder stock. What will happen if copper touches aluminium in a damp environment?

Pete

[Silver_Surfer]

These patches are I would assume were anodes, though there are no threaded bolts ends sticking out. Can they be glued? I saw it at time of haul out but was focused on the rudder bearing issue and forgot to follow up on it. Going to have yard ck it out now maybe that’s where the green wire supposed to attach to? Perhaps since the boat was neglected that is why the lower bearing deteriorated?

[Breaking Waves]

Originally Posted by Silver_Surfer

Attachment 206409
anodes,.... Can they be glued?

Not really - they have to have a metal electrical connection, and they erode so glue will usually not hold them in place.

[Silver_Surfer]

yes that is a anode on the prop bracket, there is one on shaft and another on maretec prop cap. what are the patches then? could that the threaded bolts ends also rotted off and just left the patches. the boat sat for some years i heard with very little maintenance or none.

[EngNate]

It seems unusual that the rudder shaft is aluminium, but in that case you do not want it connected to bronze and SS metals, it will definitely be happier on its own. Is the rudder blade fiberglass or encased in fiberglass or something else? If it is bronze then the shaft will definitely not be aluminium, or sure should not be.

[Frankly]

Can't tell from the photo but those two patches may be small Dynaplates, typically used as a ground for HF radio.

An anode must be mounted on or electrically connected to the underwater metal to be protected (ie shaft anode/zinc).

Frankly

[Silver_Surfer]

Thanks for all the input I’m going to disconnect the wire as I’ve received some info from Baltic directly that it is not recommended and the Baltic yachts group I belong to agree. Also, yes those are for the SSB that is installed on the boat.