Anodes

[13-10]

When I bought my narrowboat last year the survey stated that the Anodes on the hull had hardly any corrosion (from what I can see that still looks the case)

However the surveyor pointed out that the rudder didn't have an anode and should have one

Now I've maybe not been looking hard enough but I don't think I've seen a narrowboat with an Anode fitted to the rudder.

I'm blacking the hull in April, should I be putting an Anode on the rudder at the same time or is it a pointless exercise

[Chewbacka]

I don’t have an anode on mine either, never heard anodes on the rudder.

[mrsmelly]

Seagoing boats often have anodes on the rudder I think with their differing metals such as props, shafts. hull etc and the salt water added into the equasion it is the fitting thing to do. I have never had one on the rudder of any of my canal boats. Rightly or wrongly!!

[Alan de Enfield]

Nope no anodes on mine.

 

 

[dccruiser]

Same here ... never seen one on a narrowboat rudder though i have fitted them to outboards and drive legs.

Rick

[Alan de Enfield]

24 minutes ago, dccruiser said:

Same here ... never seen one on a narrowboat rudder though i have fitted them to outboards and drive legs.

Rick

As you would.

The slightest scratch in the paint & Aluminium drive legs (or outboards) without a Zinc anode wouldn't last very long - in fact in some waters Aluminium is used as the anode.

Extract of an article on anodes :

Aluminium anodes, alternatively, offer several advantages. They’re immune to the calcareous coating menace and are therefore well suited for use in seawater, as well as brackish and fresh water. Aluminium anodes also pack more of a punch; they either last longer than zinc anodes of the same weight, or provide the same protection as zinc in a lighter package. Their relative energy capacity is 1,108 amp hours per pound (significantly more than zinc), with a voltage of negative 1,100 millivolts. If you opt for aluminium anodes, be sure that the change is universal for all anodes used within the same bonding system.

Surprisingly, aluminium anodes are often no more costly than zinc ones. Also, because most are cadmium-free, aluminium anodes are less of a hazard to the marine environment. So, regardless of what a diver, boatyard manager or other industry pro tells you, there are several advantages, and no drawbacks, to switching to aluminium anodes.

Edited January 14, 2018 by Alan de Enfield

[Naughty Cal]

1 hour ago, Alan de Enfield said:

As you would.

The slightest scratch in the paint & Aluminium drive legs (or outboards) without a Zinc anode wouldn't last very long - in fact in some waters Aluminium is used as the anode.

Extract of an article on anodes :

Aluminium anodes, alternatively, offer several advantages. They’re immune to the calcareous coating menace and are therefore well suited for use in seawater, as well as brackish and fresh water. Aluminium anodes also pack more of a punch; they either last longer than zinc anodes of the same weight, or provide the same protection as zinc in a lighter package. Their relative energy capacity is 1,108 amp hours per pound (significantly more than zinc), with a voltage of negative 1,100 millivolts. If you opt for aluminium anodes, be sure that the change is universal for all anodes used within the same bonding system.

Surprisingly, aluminium anodes are often no more costly than zinc ones. Also, because most are cadmium-free, aluminium anodes are less of a hazard to the marine environment. So, regardless of what a diver, boatyard manager or other industry pro tells you, there are several advantages, and no drawbacks, to switching to aluminium anodes.

Magnesium anodes for fresh water, aluminium for brackish or a mixture of salt and fresh water and zinc for salt water use.

We switched to aluminium on our stern drive from magnesium as the mags were not lasting with our mixture of fresh, brackish and salt water use. They are now wearing at a better rate and still providing the right protection to the expensive under water gear.

[Alan de Enfield]

15 minutes ago, Naughty Cal said:

Magnesium anodes for fresh water, aluminium for brackish or a mixture of salt and fresh water and zinc for salt water use.

We switched to aluminium on our stern drive from magnesium as the mags were not lasting with our mixture of fresh, brackish and salt water use. They are now wearing at a better rate and still providing the right protection to the expensive under water gear.

That indeed was the 'mantra' I was brought up with - however, as things move on the latest 'scientific thinking' coming out of the USA is Aluminium for everything from Fresh to Salt.

[Naughty Cal]

37 minutes ago, Alan de Enfield said:

That indeed was the 'mantra' I was brought up with - however, as things move on the latest 'scientific thinking' coming out of the USA is Aluminium for everything from Fresh to Salt.

They did switch over at the marina workshops here to all aluminium on their services but have since gone back to mags for boats that don't venture into brackish or salt water as the aluminium anodes were becoming calsified and not working properly.

[Alan de Enfield]

4 minutes ago, Naughty Cal said:

They did switch over at the marina workshops here to all aluminium on their services but have since gone back to mags for boats that don't venture into brackish or salt water as the aluminium anodes were becoming calsified and not working properly.

Maybe Lincoln's water is particularly 'hard', I know our builders had to incorporate some wonderful 'magnet' into our water supply.

But Burton Waters experience is interesting although at odds with latest research which states :

Aluminium anodes, alternatively, offer several advantages. They’re immune to the calcareous coating menace and are therefore well suited for use in seawater, as well as brackish and fresh water.

 

[13-10]

Thanks for the replies and reinforces what I thought. Will be sure to avoid the Calcareous Coating Menace

[Naughty Cal]

On 14/01/2018 at 16:44, Alan de Enfield said:

Maybe Lincoln's water is particularly 'hard', I know our builders had to incorporate some wonderful 'magnet' into our water supply.

But Burton Waters experience is interesting although at odds with latest research which states :

Aluminium anodes, alternatively, offer several advantages. They’re immune to the calcareous coating menace and are therefore well suited for use in seawater, as well as brackish and fresh water.

 

Certainly not what was experienced here.

You are correct though the water is very hard. It leaves a lime coating on the bow which is a pain to remove.

[Momac]

Last time lifted out I had a hard coating to remove which seemed to be limescale - so this is not confined to the fossdyke.

Anodes may develop coating due to the sacrificial corrosion and unfortunately this can impair the effectiveness of the anode.

The following picture shows corrosion on the anode and brown limescale on the outdrive 

But it all cleaned up okay

.

 

[Momac]

Here is a special bicycle anode on an friends boat

.

[WotEver]

30 minutes ago, MartynG said:

Here is a special bicycle anode on an friends boat

How many cycles can he get out of a set of batteries?

[David Mack]

11 hours ago, MartynG said:

Last time lifted out I had a hard coating to remove which seemed to be limescale - so this is not confined to the fossdyke.

Anodes may develop coating due to the sacrificial corrosion and unfortunately this can impair the effectiveness of the anode.

The following picture shows corrosion on the anode and brown limescale on the outdrive 

But it all cleaned up okay

.

 

The corrosion looks to be a bit more severe on the far drive.

[Alan de Enfield]

6 minutes ago, David Mack said:

The corrosion looks to be a bit more severe on the far drive.

Maybe he hasn't noticed that the boat tends to 'pull' to one side when under power.