Bonding

[Comodave]

Most boats will change the anodes each year. When we had a boat in San Diego the anodes needed changing every 4 or 5 months. Each boat is different, you just need to figure out your boats schedule. If it is really eating up anodes then it needs some investigation. Once a year isn’t bad IMO.

 

[Tator]

So, is okay to have aluminium anodes on the underwater stuff and zincs on the engine heat exchangers? Is it okay (and are they available) to use aluminium anodes in the heat exchangers?

Tator

 

[Comodave]

Yes, the engine hear exchangers and the boat underwater are different bodies of water so different types of anodes can be used. I would use all aluminum anodes if the heat exchanger anodes are available in aluminum in your size. I use aluminum underwater and magnesium in the engines because I can’t find aluminum in the engine heat exchanger size.

 

[backinblue]

Charlie, not exactly the answer I expected from you after the other posts. Really, the transom zinc is doing the job. Of course it is, but the underlying condition has not been identified why it has to be replaced twice a season instead of once every two years.
I would have concerns if I had to replace a transom zinc once every year.

I have the same issue and haven't found the cause yet. My transom zinc is severely corroded after a 6 mo season as are many of the smaller zincs.

 

[Bacchus]

So, is okay to have aluminium anodes on the underwater stuff and zincs on the engine heat exchangers? Is it okay (and are they available) to use aluminium anodes in the heat exchangers?

Tator

Yes, the engine hear exchangers and the boat underwater are different bodies of water so different types of anodes can be used. I would use all aluminum anodes if the heat exchanger anodes are available in aluminum in your size. I use aluminum underwater and magnesium in the engines because I can’t find aluminum in the engine heat exchanger size.

I switched all to alum when I bought current boat.
Try Performance Metals for pencil anodes. I looked around for sources for several sizes and had trouble finding some until I found PM. They are made well with a steel rod/wire in the center of the alum rod to help prevent break off and that does seem to work... not 100% but 95%? Of the time.
They sell through dealers and I found some listed online but couldn't find one retailer with all my sizes listed. I suppose they would special order but proffered to avoid having order split and waiting on some. When I contacted them they looked up my location and no dealers close so they said order direct from them OK.

 

[Bacchus]

ART
"Make sure when leaving boat for any duration to have a master switch turned to off... that completely isolates the battery bank."

REALLY!
How many do or recommend this?
Turning off ALL bilge pumps when leaving a boat NOT a recommended practice. And most (good IMO) boat mfg wire them "always on" bypassing your switch.
I helped keep a New boat from sinking at the dock this season that had bilge pumps wired thru the switch and owner had turned it off when leaving. Combo of poor design of a drain and rain water making the boat sit lower was immediate cause.
The manufacturer gave a full refund of $ and owner bought another boat.
DO NOT TURN OFF BILGE PUMPS!
And if you leave them on I think you will find they are the source of problems many times w DC leakage... wires closest to the water inside and sometimes in close proximity to other thru hulls.
Find and fix problems don't just shut them off!

 

[Alisske]

REALLY!
How many do or recommend this?
Turning off ALL bilge pumps when leaving a boat NOT a recommended practice. And most (good IMO) boat mfg wire them "always on" bypassing your switch.
I helped keep a New boat from sinking at the dock this season that had bilge pumps wired thru the switch and owner had turned it off when leaving. Combo of poor design of a drain and rain water making the boat sit lower was immediate cause.
The manufacturer gave a full refund of $ and owner bought another boat.
DO NOT TURN OFF BILGE PUMPS!
And if you leave them on I think you will find they are the source of problems many times w DC leakage... wires closest to the water inside and sometimes in close proximity to other thru hulls.
Find and fix problems don't just shut them off!

I am good at mechanical, carpentry, fiberglass, gelcoat. I am so so on electric. (I can install anything electric correctly, but diagnosing is sort of a dark art)

That being said, my bilge pumps are wired to a switch, and then have a fused wire running to a different battery in the bank. (So two positive wires for each pump, one to switch, one to battery with fuse)

I turn the main switch to off every time I leave the boat. I grew up that way commercial fishing with my pop. (I would always clean and put the boat on the mooring while my pop ran up to the market to offload the catch). If he went to start the boat the next morning and the switch was on.........well, i would get hell about it. Lol)

 

[psneeld]

REALLY!
How many do or recommend this?
Turning off ALL bilge pumps when leaving a boat NOT a recommended practice. And most (good IMO) boat mfg wire them "always on" bypassing your switch.
I helped keep a New boat from sinking at the dock this season that had bilge pumps wired thru the switch and owner had turned it off when leaving. Combo of poor design of a drain and rain water making the boat sit lower was immediate cause.
The manufacturer gave a full refund of $ and owner bought another boat.
DO NOT TURN OFF BILGE PUMPS!
And if you leave them on I think you will find they are the source of problems many times w DC leakage... wires closest to the water inside and sometimes in close proximity to other thru hulls.
Find and fix problems don't just shut them off!

To answer....ya gotta know how the boat is wired.


Some have manual power from a main panel but have float switches direct to a battery or battery bus/fuse block. So there it may not matter.


But having raised probably hundreds of bats, most who had dead or disconnected batteries (granted usually smaller boats)...I agree a totally dead ship without bilge pump capability is a bad idea.


Even tiny solar power can keep batteries topped off these days if the only draw is occasional pump cycling.


So just sorta repeating what you said...I agree...make sure bilge pumps stay on or rewire so they can.

 

[backinblue]

Most bilge pumps I have seen are still connected to power even if the main power switches are turned off.

 

[psneeld]

Most bilge pumps I have seen are still connected to power even if the main power switches are turned off.

In many (probably much more commercial, the USCG like the idea to prevent major fuel/oil spills) circumstances nowadays where vessels carry a good mount of diesel....bilge pumps are swiched (CBs maybe) so you can secure them if you have a major fuel/oil leak onboard but still want power to other systems.


I have a separate fuse bock that powers bilge pumps and alarm circuits that stay live if I leave that panel on and the main batt switches. If I want to disconnect everything else, I use the main panel breaker from the Batt DC buss.


So I can turn bilge pumps on or off completely without affecting other systems.

 

[Bacchus]

"Make sure when leaving boat for any duration to have a master switch turned to off... THAT COMPLETELY ISOLATES THE BATTERY BANK."

To clarify my point I added the emphasis to the quoted recommendation... and still say thats a bad practice if it truly completely isolates the batty bank

I have no problem with using a batty switch.
Also agree owners should know (find out) how their various systems are wired and specifically which remain energized.
My only other point is isolating some loads and leaving others powered will not necessarily avoid leakage and associated issues... especially if those remaining powered frequently have wiring submerged in bilge water.
I will say that most? bilge pump wiring that has a manual and auto switches have 2 fuses or breakers... owners should also know where the always on power to bilge pumps is protected by fuse or breaker for the reason stated re potential for fuel discharge overboard. Simply shutting off a breaker in a panel that is fed through the batty sw will not kill the pump completely if the auto operation bypasses the batty switch and (should) have a separate fuse / breaker.

 

[CharlieJ]

@Soo-Valley

Charlie, not exactly the answer I expected from you after the other posts. Really, the transom zinc is doing the job. Of course it is, but the underlying condition has not been identified why it has to be replaced twice a season instead of once every two years. I would have concerns if I had to replace a transom zinc once every year.

Steve, the answer I gave is the best I can do without performing a full corrosion survey.

The idea that anodes "should" last x months/years is not realistic and not based on the electro-chemical reactions that are taking place. If a boat in its home slip historically has the anodes replaced every 8 months at the 50% wastage point and the wastage rate goes to every 4 months with no additional underwater metal added to the cathodic load, no changes to the salinity or flow of the water, etc. then there may be a problem that needs to be resolved. A corrosion survey will determine if there is or is not an issue.

FWIW, some owners wait until a hull anode is almost to the internal steel before they change it while some change at the recommended 50% wastage point. Too many variables to give a technically sound answer on a forum where there is no real data presented.

The "underlying condition" that you are referring to may be that in that body of water, with the cathodic load on the anodes, the size and composition of the anodes, his cathodic protection system is working exactly as it should.

 

[Comodave]

When they are wasting away they are doing their job. If they are wasting away too fast then I agree that you probably need a professional marine electrician to do a corrosion analysis. Maybe you need more or bigger anodes.

 

[SteveK]

Thanks Charlie, that last is what I expected the first time, to keep a continuity so to speak.
I guess I have not experienced more than once per year anode changes, with previous boats which were FG and one other wood, maybe due to not bonding thru hulls and not bonding DC- to AC-. My anodes wear showing they are at work, but if they ever wear twice a year I will be searching for the cause.

 

[Steve DAntonio]

Many of the questions being posed in this case can be answered with a reference electrode test. Otherwise, you are flying blind where anode consumption rates are concerned. I'm often asked about anode consumption rates, it's really impossible to give an informed answer because there are so many variables as Charlie J noted.

Reference electrodes have been discussed in this forum on several occasions, however, here's a short article on the subject https://stevedmarineconsulting.com/wp-content/uploads/2019/10/Anodes.pdf

Also, magnesium anodes should never be used, on the hull or in heat exchangers, except in fresh water.

I'm a fan of aluminum anodes, however, I have had issues with the pencils in heat exchangers getting stuck, as the aluminum pencils swell slightly as they erode. You can safely use zinc there if you encounter this problem, and aluminum elsewhere.

Galvanic isolators will protect a vessel from galvanic corrosion that is caused by other nearby vessels, up to a point, the galvanic isolator has a limit. Isolation transformer protection has no limit, its protection from corrosion caused by other vessels is absolute. Every vessel that is plugged into shore power should be equipped with at least a galvanic isolator.

Neither of the above devices will prevent stray current corrosion which almost always originates on the affected vessel, and not from nearby vessels.

 

[backinblue]

Many of the questions being posed in this case can be answered with a reference electrode test. Otherwise, you are flying blind where anode consumption rates are concerned. I'm often asked about anode consumption rates, it's really impossible to give an informed answer because there are so many variables as Charlie J noted.

Reference electrodes have been discussed in this forum on several occasions, however, here's a short article on the subject https://stevedmarineconsulting.com/wp-content/uploads/2019/10/Anodes.pdf

Also, magnesium anodes should never be used, on the hull or in heat exchangers, except in fresh water.

I'm a fan of aluminum anodes, however, I have had issues with the pencils in heat exchangers getting stuck, as the aluminum pencils swell slightly as they erode. You can safely use zinc there if you encounter this problem, and aluminum elsewhere.

Galvanic isolators will protect a vessel from galvanic corrosion that is caused by other nearby vessels, up to a point, the galvanic isolator has a limit. Isolation transformer protection has no limit, its protection from corrosion caused by other vessels is absolute. Every vessel that is plugged into shore power should be equipped with at least a galvanic isolator.

Neither of the above devices will prevent stray current corrosion which almost always originates on the affected vessel, and not from nearby vessels.

Hi Steve,

I appreciate your expertise on the subject. I did an electrode test on my boat this season and it was in the proper range, with and w/o shore power. My boat has an isolation transformer. However, my zincs wear away much quicker than they should and I get lots of barnacles on the underwater metals. I think the pain is flaking off due to some electrical issue. What's my next step?

 

[CharlieJ]

@backinblue

However, my zincs wear away much quicker than they should

What is this comment based on? Has the wastage in the current slip increased from one 3-month period to the next?

As I tried to explain upthread, anode wastage is a function of a lot of variables: cathodic load, salinity of the water, water flow, how much the boat is being used, etc. If your "normal" anode wastage was 50% in 10 months at your home slip and it is now 50% in 4 months, that indicates that some variable has changed, and the cause needs to be investigated. It does not specifically indicate that something is wrong.

 

[Art]

This post is to request assistance from a Moderator

There are some threads in which I have great interest to stay appraised. This thread is one.

Unfortunately, and although, I have posted on some threads [this is one] the email notification for new posts comes through sporadically at best [such as is occurring regarding this thread]. Which makes me need to go back onto TF main page and punch up this [and/or other threads] of which I've been not receiving new post notifications.

Please understand; I have not altered any of my TF keys for a very long time.

Your looking into this is appreciated! I wonder if others are experiencing this hold up in email notifications??

Happy TF Boat-Forum Daze! - Art

 

[SteveK]

It was mentioned that stray current can originate from a bilge pump, bilge pump wiring. I wonder why a bilge pump is not bonded.
I am thinking a simple metal or zinc plate under the the pump tied back to ground B-

 

[Comodave]

This post is to request assistance from a Moderator

There are some threads in which I have great interest to stay appraised. This thread is one.

Unfortunately, and although, I have posted on some threads [this is one] the email notification for new posts comes through sporadically at best [such as is occurring regarding this thread]. Which makes me need to go back onto TF main page and punch up this [and/or other threads] of which I've been not receiving new post notifications.

Please understand; I have not altered any of my TF keys for a very long time.

Your looking into this is appreciated! I wonder if others are experiencing this hold up in email notifications??

Happy TF Boat-Forum Daze! - Art

A few days ago the email notifications stopped for me. Thrned out that we have a laptop that we rarely use. Some settings on it changed, maybe an automatic update, and it was putting all the TF emails in junk folder. So I would not see them on my iPad. Changed the setting and all was good for a few hours. Then it happened again. Changed the setting on the laptop again and so far it is ok. Maybe check all of your computers and see if they are in the junk folder???

 

[boatpoker]

It was mentioned that stray current can originate from a bilge pump, bilge pump wiring. I wonder why a bilge pump is not bonded.
I am thinking a simple metal or zinc plate under the the pump tied back to ground B-

How would you attach that metal plate to the plastic casing of the bilge pump and how would that complete a bonding circuit ?

 

[Steve DAntonio]

Hi Steve,

I appreciate your expertise on the subject. I did an electrode test on my boat this season and it was in the proper range, with and w/o shore power. My boat has an isolation transformer. However, my zincs wear away much quicker than they should and I get lots of barnacles on the underwater metals. I think the pain is flaking off due to some electrical issue. What's my next step?

Charlie J's response says it all, many things can affect anode consumption, there is no "normal" lifespan for an anode, it varies from vessel to vessel. Barnacles on protected metals is entirely normal (if only all we had to do was cathodically protect underwater metals to keep them zinc free!)

Having said that, flaking bottom paint around protected metals is indicative of excess alkaline production, which in turn is indicative of over-protection. What were your reference electrode readings, and is the vessel FRP, with bronze and stainless shaft alloy underwater metals?

There is an ABYC E-2 formula for the amount of anode protection that is needed, it would be worth checking to make sure your anode quantity is correct.

 

[SteveK]

How would you attach that metal plate to the plastic casing of the bilge pump and how would that complete a bonding circuit ?

Just thinking out loud, no idea. If a B+ current comes out and into bilge water, then the pad idea might give it a short cut route to ground.
Still trying to understand stray current source and path.

 

[SteveK]

A few days ago the email notifications stopped for me. Thrned out that we have a laptop that we rarely use. Some settings on it changed, maybe an automatic update, and it was putting all the TF emails in junk folder. So I would not see them on my iPad. Changed the setting and all was good for a few hours. Then it happened again. Changed the setting on the laptop again and so far it is ok. Maybe check all of your computers and see if they are in the junk folder???

If you are using a third party email program then you should also log into the IP server for your emails. It may be from the source sending it to junk and not your at home devices. There you would tell it this is not junk mail.
Every update of the operating system causes an issue.

 

[Comodave]

I hate updates in general. Unless they are fixing a specific problem all they do is change stuff and make it more difficult to work with.

 

[CharlieJ]

@Soo-Valley #83

Just thinking out loud, no idea. If a B+ current comes out and into bilge water, then the pad idea might give it a short cut route to ground.
Still trying to understand stray current source and path.

Hopefully this will clarify the two processes: galvanic and stray current corrosion.

For galvanic corrosion, or its beneficial cousin cathodic protection, to occur there must be two dissimilar metals, electrically connected and immersed in the same electrolyte.

For stray current corrosion, or its beneficial cousin impressed cathodic protection, to occur there must be two metals, one connected to the voltage source B+ and the other to B-. The B+ connection becomes the anode which loses electrons to the wire and positive ions to the electrolyte. The metal connected to B- becomes the cathode in this anode/cathode couple and is protected if the voltage shift is more negative than -200mVDC against a reference cell.

Fundamental to the above is:
1. We are using electron flow, not conventional current flow.
2. Electrons flow in the metal components. Ions flow in the electrolyte.

Hope this helps.

Calder's book has some really good information and graphics on this subject if you want to learn more.

 

[Tator]

If you are using a third party email program then you should also log into the IP server for your emails. It may be from the source sending it to junk and not your at home devices. There you would tell it this is not junk mail.
Every update of the operating system causes an issue.

My notifications stopped as well a few weeks ago to my yahoo address. They are not in my spam folder. As far as I'm aware, no settings were changed.

Tator