Anodes - in theory...

[sheral]

Would adding extra anodes to a boat help with the overall wear of anodes at other locations on the boat?

The thruster anode on our R21EC was quite worn so I now have replacement(s) anodes for it. I am not sure what the original thruster anode was made of but the replacement(s) are aluminum - which apparently last longer than zinc.

By the condition of the anode on the thruster from being in the water for only a few months last year, I doubt it would make it through a long season and it is way too difficult (due to where we live) to pull the boat part way through a season to replace it. The Sidewinder manual says to add an extra thruster anode should this be the case. Anyone know how this would be done properly? I suspect a cylindrical shaped anode would be sized to fit between the thruster prop and the existing bullet shaped anode - to extend the anode?

My other thought is to add an extra anode to the bottom of the skeg - by adding another tear drop shaped anode that would mirror the one on the top of the skeg.

I would prefer not to have a ‘bonding zinc’ hanging off the side/back of the boat.

 

[SnugTug]

Hanging a sacrificial "grouper" type anode over the side at the marina might be your best solution. Most of the electrolysis happens at the dock with stray current from "hot" neighboring boats. I haven't heard of anyone adding more or larger zincs to the thruster before - I would be concerned that doing this could affect performance and possibly create unwanted vibration. larger zincs could also break loose once degraded and possibly get jammed in the prop causing at least a shear pin failure or worse.

Not an expert on this so I will be interested in others' opinions.

 

[Scuffy]

Conventional wisdom that was explained to me was to use a zinc grouper hung over the side as previously mentioned attached to the negative terminal on a battery while on shore power at the marina. Plus add a Galvanic Isolator which wires into the negative lead on the shore power cable once inside the boat. These items reportedly double the life of your zincs.
I shall see as I just changed out our zincs and already have the zinc grouper plus we just added a Galvanic Isolator.

 

[stwendl]

Sacrificial anodes hung over board will help to some small degree. Adding a galvanic isolator on your shore power will be better

However, if your marina is hot then you may have a varying voltage field in the water. By that I mean that the there is for instance a different voltage potential at your transom compared to the bow. In that case you may need to hang multiple anodes and make sure they are bonded to the metals that are in touch with water in that area

The boat is connected internally among all metal parts already. Ironically if the rudder, shaft, thruhulls etc were not connected to each other corrosion would not be as severe. Kind a makes one wonder who benefits from those rules


Even in terms of lightning protection, a grounded boat will be more attractive to a lightning strike then a non grounded boat
But that discussion has been exercised ad nauseum in the sailing community already.

Point in case if working with electric panels one wears isolating shoes and gloves 🙂

 

[Captain Nice]

I used a zinc "grouper" while the boat was in salt water for the month of February. There was significant deterioration of all the anodes on the boat, but nothing discernible to the grouper - didn't work for me.

CN

 

[stwendl]

I used a zinc "grouper" while the boat was in salt water for the month of February. There was significant deterioration of all the anodes on the boat, but nothing discernible to the grouper - didn't work for me.

CN

Of course you connected the grouper to the rest of the boats metals
"Frame" work to gloss the electrical circuit. If this still did not help then the anodes were different material

 

[Captain Nice]

Evening stwendl,

Yes, the zinc grouper was clipped to the negative bonding system. And as far as I can tell, Ranger uses zinc anodes (although the bow thruster's appears to be aluminum). I dunno...

CN

 

[Levitation]

To the OP - aluminum is used for fresh water anodes (magnesium also)
Zinc is the only anode to use in salt water (and it is less effective in fresh water)
If that was a factory aluminum anode on the thruster on a boat intended for salt water, likely there was a mix up on the factory floor as to what was ordered.

 

[Brian B]

To the OP - aluminum is used for fresh water anodes (magnesium also)
Zinc is the only anode to use in salt water (and it is less effective in fresh water)
If that was a factory aluminum anode on the thruster on a boat intended for salt water, likely there was a mix up on the factory floor as to what was ordered.

SidePower recommends aluminum anode in salt water on our size thrusters. Here is the document from the company explaining why.
http://www.imtra.com/COLLATERAL/DOCUMEN ... ONDING.PDF

 

[SGIDAVE]

SidePower recommends aluminum anode in salt water on our size thrusters. Here is the document from the company explaining why.
http://www.imtra.com/COLLATERAL/DOCUMEN ... ONDING.PDF

This is what SidePower says about Aluminum alloy anodes:
(copied from pdf linked above)

Aluminum Alloy Anodes
Side‐Power now supplies aluminum alloy anodes for most models; zinc anodes are no longer
available for SP, SE and SH model thrusters. Zinc anodes continue to be supplied for all HP model
thrusters.
• Aluminum alloy anodes provide superior protection over zinc anodes in salt and brackish water.
• Aluminum alloy anodes work in fresh water and are the only anode that is safe for both salt and
fresh water.
• Aluminum alloy anodes potentially last up to 50% longer than zinc anodes.
• Aluminum alloy anodes are now competitively priced.
• Aluminum alloy anodes are widely used in military and commercial fleet applications because of
their superior protection and reduced maintenance cost.

and this is from Boatzincs.com

For vessels with AC shorepower connections and no galvanic isolation Chart A
and
For vessels with no AC shorepower connections, or AC shorepower connections with galvanic isolation Chart B

It looks like there is a bit of science involved in the rational choice of Zn v Al alloy anodes. Whether connected to AC shorepower, presence of galvanic isolation, and water type being key elements in decision.

dave

 

[Levitation]

First, an admission. Due to vapor lock of the prefrontal lobe I transposed aluminum for fresh water where I intended to write magnesium with Al as a possible for brackish.
OK, the manufacturer has spoken on the thrusters and Al it will be since I don't have a choice.
Now if Al is the answer and Zn has been wrong all along, then why are they changing the anodes on only part of their models instead of all?

Hmmm, a bit of noodling shows this:
http://www.boatzincs.com/zinc-vs-aluminum-chart.html
Notice the big reason given - cost.

Then there is this where the author blames zinc for releasing cadmium into the environment.
http://www.defender.com/html/zincs_info.html

And this:
http://www.talkofthedock.com/gear-revie ... -solution/

If you compare the Defender pages to the boat zinc page you will notice the conflict on aluminum. Older articles and charts share this confilict.

And then there is this rambling, disjointed 'experiment' that is quite interesting in that it seems to provide results opposite the new mantra of aluminum is best.
http://tinyurl.com/zro9z2r

And finally a complaint: Who changed the rules of the game when I wasn't looking?!
From now on I expect to be consulted before any changes in the way the world works, (sheesh, mumble, mutter %^#@!)

It appears I have to decide how to approach this. I prefer zinc (after a lifetime of using it. But given I won't be able to get zinc for the thrusters I am likely forced to change everything to aluminum - or cast my own thruster anodes whilst flipping off the 'experts" and I am just bull headed enough to do that. :mrgreen:

 

[HRowland]

Denny,

The underwater metal on Side Power thrusters is electrically isolated. Using aluminum alloy anodes on the thrusters (they do contain 5% zinc and a trace of indium) and zinc on the rest of the boat is fine.

From the Boatzincs web site:

Imtra Side-Power thrusters are engineered to have their underwater metals electrically isolated from the rest of the boat. This means that there is no electrical path available for the thruster (or its anodes) to interact with any other underwater metals (or anodes) either on or adjacent to your boat. You can, and should, continue to use zinc anodes elsewhere on your boat while upgrading your Imtra Side-Power thruster to these new, technically superior aluminum anodes.

Howard

 

[sheral]

And finally a complaint: Who changed the rules of the game when I wasn't looking?!
From now on I expect to be consulted before any changes in the way the world works, (sheesh, mumble, mutter %^#@!)

It appears I have to decide how to approach this. I prefer zinc (after a lifetime of using it. But given I won't be able to get zinc for the thrusters I am likely forced to change everything to aluminum - or cast my own thruster anodes whilst flipping off the 'experts" and I am just bull headed enough to do that. :mrgreen:

:lol: :lol: :lol: