Hanging an annode over the side!

[Nostrodamus]

In France a lot of boats hang an old annode over the side on a metal wire attached to a stantion. I understand that for a metal boat this is a good idea but does it help on a GRP boat?

If so should it be attached to the bonding circuit?

 

[Talbot]

In France a lot of boats hang an old annode over the side on a metal wire attached to a stantion. I understand that for a metal boat this is a good idea but does it help on a GRP boat?

If so should it be attached to the bonding circuit?

I have one hung on each quarter (on a cat), and have some nice canvas bags made up to keep the ande and cable in when underway. The anodes are connected to the gantry which is bonded to the engine.

It significantly reduces the wear on the autoprop anodes.

 

[Salty John]

Yes, it helps on a grp boat also, to reduce erosion of the fixed anodes.

Yes, it needs to have a good connection to the bonding system.

 

[VicS]

In France a lot of boats hang an old annode over the side on a metal wire attached to a stantion. I understand that for a metal boat this is a good idea but does it help on a GRP boat?

If so should it be attached to the bonding circuit?

Yes it can help with protecting vulnerable bits, It may also extend the life of your fixed anodes.

It must hang fairly close to the item(s) it is to protect .. which might be difficult if we are considering a sail drive.

There must be a good low resistance connection between it and the item it is to protect. Connection to the existing anode bonding should suffice. A direct connection might be better.

Hanging anodes are used extensively to protect aluminium hulls.

 

[Tranona]

Commonly used for saildrives in places where anode erosion is high - particularly in the old 110 and 120 Volvo legs where the anode is half the size of the later 130 leg - and difficult to replace without hauling out. Needs to be connected straight to the gearbox housing inside the boat - not the engine as the two are isolated. Needs to hang as close to the saildrive as possible.

 

[saltylegs]

Often used on race boats that don't want to fit an anode because of the increased drag. But make sure everything is bonded to the anode conection points.
to protect the P bracket and prop swing the anode on a bridle that will allow the anode sink below the rudder and it can then be moved forward and upwards by shortening each end of the bridle to pre marked points so as to get it close to the prop.
END OF THE BRIDLE TO THE GEAR LEVER/ENGINE START AND FIT LABEL TO RETIEVE BEFORE STARTING.

 

[Cloven]

In France a lot of boats hang an old annode over the side on a metal wire attached to a stantion. I understand that for a metal boat this is a good idea but does it help on a GRP boat?

If so should it be attached to the bonding circuit?

We keep our boat in France and yes we use a hanging anode all the time, except when under way!. Problem we have is that our home berth is fresh water but we sail at sea. Zinc anodes stop working in fresh water and magnesium anodes "melt" in salt water. So, we have aluminium shaft and hull anodes; a magnesium hanging anode when berthed in fresh water and a zinc hanging anode when berthed in salt water.

As for your second question, yes, the hanging anode is bonded through the hull to the hull anode; engine; P bracket; etc etc

 

[alant]

We keep our boat in France and yes we use a hanging anode all the time, except when under way!. Problem we have is that our home berth is fresh water but we sail at sea. Zinc anodes stop working in fresh water and magnesium anodes "melt" in salt water. So, we have aluminium shaft and hull anodes; a magnesium hanging anode when berthed in fresh water and a zinc hanging anode when berthed in salt water.

As for your second question, yes, the hanging anode is bonded through the hull to the hull anode; engine; P bracket; etc etc

Why, apart from the additional wine content of the water discharged from heads, is this necessary only in France?

Some seen, but not that common in UK waters.

 

[maby]

Definitely worth it. We dangle an auxiliary anode whenever we are on shore power and a good 50% of it erodes in a year. Without the auxiliary anode, the equivalent amount would have eroded from your fixed anodes - and they are a lot more expensive to replace.

 

[Nostrodamus]

So, It is a good idea and I need to hang it as near to my saildrive as possible on a metal wire.
I have bonding through out the boat onto an electrical zinc saver. what is the best way to attach the wire holding the annode and where to?

 

[maby]

So, It is a good idea and I need to hang it as near to my saildrive as possible on a metal wire.
I have bonding through out the boat onto an electrical zinc saver. what is the best way to attach the wire holding the annode and where to?

Keep it as short as reasonably possible and connect it to the inner contact of the fixed anode. I would not get too paranoid about positioning - anywhere close to the stern will do - at least if you are not relying on the auxilliary anode alone, as some racers do.

As for the auxilliary anode, I usually buy one of those teardrop anodes that is moulded onto a steel bar with mounting holes drilled through each end. The steel will take solder very easily if you apply a little flux and use a small blowtorch to heat it - then you can solder a flexible wire to it - use an insulated stranded wire - reasonable thick.

 

[Tranona]

So, It is a good idea and I need to hang it as near to my saildrive as possible on a metal wire.
I have bonding through out the boat onto an electrical zinc saver. what is the best way to attach the wire holding the annode and where to?

There is really no need to have one unless you are experiencing heavy erosion of your saildrive anode. You have a two part anode which is easily replaced by diving rather than hauling out. Most people have no problem with saildrive anodes except if they are plugged into shorepower without a galvanic isolator. In the Med, mine lasted 5 years - and that is half the size of yours! There is unlikely to be anything else on your boat that needs an anode.

However, if you do want to use one, then use the proper MG Duff one and connect it to the saildrive housing inside the boat - not the engine as that is insulated from the saildrive. If you are really paranoid about it then fit the Bruntons retractable anode which is a much more elegant way of getting extra anode near the saildrive.

 

[Nostrodamus]

When I bought the boat a year ago there was corrosion on the saildrive leg and the prop which was so bad the leg and prop needed to be changed at a cost of a good few thousand pounds so yes, I am a bit paranoid. If the small cost of hanging a annode can prevent this and help save my exisiting annodes then I believe it is worth it.

 

[Tranona]

Remember though that your new leg has an anode twice the size of the old one - and you don't know why the old one failed. Could have been neglect or moored somewhere with stray currents. Perhaps you should monitor the erosion first - assume you have spare anodes with you if you need to change it. Hanging anodes are not very effective as it is difficult to get them near enough to the saildrive. Their only real advantage as somebody else pointed out is if you are alternating between fresh and seawater so you can hang a magnesium anode over the side in fresh water.

 

[maby]

when all's said and done, it is so easy and cheap to hang an auxilliary anode, that it just makes sense. Most of us are just not sufficiently fit and experienced to dive and replace the primary anodes under water, so anything that postpones the need to change them is worthwhile provided it doesn't cost too much. If it takes me half an hour to make up and install an auxilliary anode, and costs less than £20, then it's worth it in my book even if it only delays the need to change the main anodes by a couple of months...

My experience on a yacht (admittedly with shaft drive) is that the presence of the auxilliary anode extended the life of our hull anodes by a lot more than that.