My anodes aren't wearing away ?????

Rivers & creeks

Rivers & creeks

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I'm new to hull anodes after many years with outboards and no skin fittings.

The boat has just been lifted out for 3 months and has:

- Large lozenge shaped anode 5 feet from the stern, 20% worn so left unchanged at launch February 2012 - no more discernable degradation on haul out this week.

- Disc anode on steel rudder - new in February 2012 - almost no discernible degradation on haul out

- Pear shaped anode on other side of rudder - reasonable signs of degradation on haul out.

Just to check first - wire should go from engine block (the common ground for the yacht electrics) to the hull anode? It's got two posts, should there be a wire to each or just one?

It is possible to link the rudder back to the engine block - but should I?

Those questions plus the issue of why so little visible signs of degradation in the anodes? BTW we don't yet have a galvanic isolator fitted, we're on 230v permanently when afloat and there are large steel pilings close by.

The prop and rudder showed no signs of any galvanic pitting.

Thanks for your help!
 
Lazy Kipper said:
I'm new to hull anodes after many years with outboards and no skin fittings.

The boat has just been lifted out for 3 months and has:

- Large lozenge shaped anode 5 feet from the stern, 20% worn so left unchanged at launch February 2012 - no more discernable degradation on haul out this week.

- Disc anode on steel rudder - new in February 2012 - almost no discernible degradation on haul out

- Pear shaped anode on other side of rudder - reasonable signs of degradation on haul out.

Just to check first - wire should go from engine block (the common ground for the yacht electrics) to the hull anode? It's got two posts, should there be a wire to each or just one?

It is possible to link the rudder back to the engine block - but should I?

Those questions plus the issue of why so little visible signs of degradation in the anodes? BTW we don't yet have a galvanic isolator fitted, we're on 230v permanently when afloat and there are large steel pilings close by.

The prop and rudder showed no signs of any galvanic pitting.

Thanks for your help!
Click to expand...

are the anodes a gold / bronze colour now :D
 
Check the bonding between the anodes and what they are fitted to protect.

Dont forget flexible shaft couplings must be bridged to complete the circuit from anode via engine block and shaft to prop.

Only necessary to connect to one stud on the anode but check the continuity through to the anode itself.

MGDuff recommend 4 mm² cable for bonding.

Useful info on MG Duff's website http://www.mgduff.co.uk/

If the rudder has its own anodes there is no need to link it back to the engine block and hull anodes.

While your shorepower earth is not bonded to the boat's own ground/anodes/ DC negative you do not need a GI but you may well once they are bonded together.
 
Lazy Kipper said:
I'm new to hull anodes after many years with outboards and no skin fittings.

The boat has just been lifted out for 3 months and has:

- Large lozenge shaped anode 5 feet from the stern, 20% worn so left unchanged at launch February 2012 - no more discernable degradation on haul out this week.

- Disc anode on steel rudder - new in February 2012 - almost no discernible degradation on haul out

- Pear shaped anode on other side of rudder - reasonable signs of degradation on haul out.

Just to check first - wire should go from engine block (the common ground for the yacht electrics) to the hull anode? It's got two posts, should there be a wire to each or just one?

It is possible to link the rudder back to the engine block - but should I?

Those questions plus the issue of why so little visible signs of degradation in the anodes? BTW we don't yet have a galvanic isolator fitted, we're on 230v permanently when afloat and there are large steel pilings close by.

The prop and rudder showed no signs of any galvanic pitting.

Thanks for your help!
Click to expand...

The so called 'Lozenge' anodes on the CW Veracity class are almost sure MG Duff 'Pear shape' type ZD77 and the round ones are either MG Duff 'Button type' ZD51 or ZD56 depending on their diameter and all are available most places.

As already said it is almost certain your circuit is not complete, I would also check the anode bolt condition and I assume you have checked they are 'Zinc' Anodes.

Mike
 
How much anode degradation do you normally get in your area/boat/water? The amount of electrolysis depends on various factors including the boat, location, salinity of the water, and how much metal is nearby e.g. old chain dumped on the seabed, other nearby boats etc. In my case I wouldn't expect to see much degradation of my anodes since February. A friends fishing boat just around the corner from me does get more degradation. So long as none of your metal components are degrading, you are probably fine. Just check that everything is protected correctly and check the continuity of all connections to anodes using a multimeter.
 
Thanks for the responses. It's brackish water except at high tide, a river runs into the scooped out harbour and means we get very small amounts of crustacean fouling, in fact very little fouling at all.

How do I use a multimeter to test the circuit? I have a continuity setting - is that all that's needed?
 
Lazy Kipper said:
Thanks for the responses. It's brackish water except at high tide, a river runs into the scooped out harbour and means we get very small amounts of crustacean fouling, in fact very little fouling at all.

How do I use a multimeter to test the circuit? I have a continuity setting - is that all that's needed?
Click to expand...
If it's brackish water that will reduce electrolysis and fouling. Yes use a multimeter with it's continuity setting - which probably makes a noise when you have continuity. You can check the continuity of the anodes to the bolts from the outside - one prong on the anode, the other on the stud end or nut, and you should get a squeaking noise. Then move inside and check from the bolts to the engine block etc. But all sounds good to me given the brackish water and lack of fouling.
 
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Lazy Kipper said:
Thanks for the responses. It's brackish water except at high tide, a river runs into the scooped out harbour and means we get very small amounts of crustacean fouling, in fact very little fouling at all.

How do I use a multimeter to test the circuit? I have a continuity setting - is that all that's needed?
Click to expand...

Use the meter either on its lowest resistance range or use the continuity setting.

Check directly between the anode and the stern gear . If you do not find a good low resistance connection check smaller portions of the circuit to find out where the problem lies.

BTW in brackish water you should be using aluminium anodes rather than zinc.

The low salt content may explain, in part at least, the low rate of loss of the anodes
 
Lazy Kipper said:
Thanks for the responses. It's brackish water except at high tide, a river runs into the scooped out harbour and means we get very small amounts of crustacean fouling, in fact very little fouling at all.

How do I use a multimeter to test the circuit? I have a continuity setting - is that all that's needed?
Click to expand...

The marina you were in earlier in the year has differing levels of anode consumption. over to chandlery side of the lift dock on the short linear is very bad
 
Robert Wilson said:
Apologies if this point has been addressed.
I thought I read on an earlier post that GRP boats don't need anodes, or the accompanying internal "hook-up" wiring.
Any views on the above presumption?

Sorry to drift the OP's subject.
Click to expand...

My 12v & shore power are totally seperate
the battery charger although "plumbed-in" is only ever manually switched & never left on.
when i leave the boat the shore power is disconnected, unless its the winter time, when mains heating is on a frost stat.
i do not have hull anodes, just anodes on the shaft & P bracket
 
35mm said:
At least if they have metal components below the waterline. If you just have an outboard, the anodes will be fitted to that.
Click to expand...

Thank you. I thought it was a bit odd, especially as my "lozenge" hull anode and my shaft anodes DO decompose.
So, on that premise, the internal "hook-up" to fittings e.g. sea-cocks, engine etc., is needed as well?
 
There is one other possibility which should show up in the resistance check (unless you dig the probe into the anode). quite often the anodes get coated in a hard whitish deposit which insulates it and prevents the circuit from working. This can either be chipped off with a chipping hammer or the point of a chisel or polished off with a wire brush. When you say your anodes are silver, they really need to be metallic and shiny!

Rob.
 
Robert Wilson said:
Now I'm totally confused, especially as when I bought the boat (1982 Javelin30) there is a "cat's cradle" of wiring linking all sorts of fittings including all the sea-cocks.
Click to expand...

Seacocks and other skin fittings should be of corrosion resistant materials and should not therefore need cathodic protection.

Although there was at one time a belief that all metal alloy under water fittings should be bonded together and to the anodes this is not now recommended.
The less unnecessary linking there is the less likelihood there is of stray currents in the cat's cradle of wiring causing corrosion or electrolysis

One of the recommendations from the MAIB in the report on the near loss of the F.V. Random Harvest a few years ago was that the skin fittings should not be linked to the vessels cathodic protection anodes
 
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