Another Anode Q

[Guest]

I have seen a lot of talk re anodes and that has prompted some questions.

Background:

I have a Hydraulic drive with no conductive link from the engine to the drive unit, other than the hydraulic oil (don't know if that is conductive)
I am on a pile mooring with rope warps
No Shorepower
2 Batteries on an off-1-both-2 switch. Left in the off position when not on the boat
Permanent power from batt 2 to bilge pump

When I bought the boat the only anode was on the prop-shaft and there is no electrical bonding between that and the engine or the rudder shaft.

Can someone please advise me if this is OK or should I be doing more.

Cheers

 

[oldsaltoz]

Re: Hydraulic conductivity

G’Day Wstobbs.
Just a note, not all Hydraulic lines are non conductive, most have steel reinforcement and ‘may’ be conductive depending on the end coupling type.
A simple test will confirm this.

Avagooday Old Salt Oz……

 

[Guest]

Re: Hydraulic conductivity

Thanks, I think that I had better test this. May change the picture significantly.

W

 

[Trevor_swfyc]

"If it isn't broken dont fix it" comes to mind.
Anhydrous hydraulic oil is not conductive, if you are correct in saying that you have no connection between the outdrive and the engine and the drive anode works then all is well. The engine which I assume is salt water cooled must be protected by its own anode usually this only last one season and must be replaced without fail otherwise you will have serious engine corrosion problems. Look in the engine handbook for where this anode is on your engine. A nice touch is to paint must check items yellow ie dip stick, anode holder, but don't get paint on the thread which could interfer with the electrical connection.
Since I converted to fresh water cooling on a Volvo 2002 the engine anode on the block is not touched, but the salt water anode on the heat exchanger is and only last 6 months, after being left initially for two seasons it had completely gone, woops.
Trevor

 

[Guest]

mmmm, now I am worried.

I have never seen any form of anode on the engine (c1975 Farymann). Just spoken to the agents and they say that this engine down not have an anode. Should I bond it to the drive unit so that it can use the one on the shaft?

I am concerned that this may cause prop issues so I wonder if it would be better to fit something else.

Wayne

 

[Miker]

Volvo MD2010

My engine handbook does not mention anything about an anode, and when I queried this with Volvo they said that it did not have one. So I assume that not all engines are alike.
I do, of course, have a prop, shaft and a hull anode fitted, and they get eaten up in that order.

 

[Guest]

Re: Volvo MD2010

For safety sake, should I fit a hull anode anyway and bond it to everything else or could that cause any damage. (See the opening post on this thread to get my setup)

Unfortunately I do not have any history to go on as this is a new boat to me and the previous owner is deceased.

 

[Miker]

Re: Volvo MD2010

I AM NO EXPERT and I will just quote what my handbook says about my engine.
"The engine's flywheel housing and transmission are electrically insulated from the engine..... The flywheel housing or transmission must under no circumstances be earthed. Earthing of these components can result in serious damage as a result of galvanic corrosion". I took this to mean, rightly or wrongly, that I should not connect an anode to the flywheel casing. Instead, I connected my hull anode direct to my prop shaft by a carbon brush.
I think that it is horses for courses, and find an expert on your engine.

 

[Trevor_swfyc]

Further information about the engine Volvo MD2020 from the maufacturer.
As Follows:
SERVICE LIFE
The MD2020 is fitted with a freshwater cooling as standard. This reduces internal corrosion and enables the engine to maintain a consistant and optimal working temperature under all conditions.
To avoid galvanic corrosion the engine is equipped with the unique electrical insulation between engine and transmission. end of quote.
So extra protection is not necessary bar that fitted to the leg by the manufacturer.
A source for anodes see advert PBO page 162 www.volvopentadirect.co.uk
a search on ANODE produced 769 products so it would be handy to know the part number you require, anodes were MG DUFF various engine makes and uses.
Trevor

 

[vyv_cox]

Despite what is often read here and elsewhere, it is impossible to protect an inboard engine from corrosion by fitting a hull anode. There is a wealth of research data showing that in a static system it is impossible to "throw" the protection of an anode more than six pipe diameters. Even then, the electrons will not go around corners, protection is largely line-of-sight. Sea water is not a conductor that can be compared to a copper wire: it has a significant resistance. So unless your water inlet pipework is remarkably short and straight you cannot expect an external anode to do anything for the engine.

In impressed current systems there is a small additional distance to be gained, and where there is internal electrical insulation, such as a sound paint film, the absolute maximum that can be obtained is 20 - 30 diameters, but this would be in a managed system.

If your hydraulic drive is internal I think there is no cause for concern. The anode on the shaft is protecting the stern gear. It can never do more than that, even with a conventional gearbox. The hydraulic drive only needs protection if it is exposed to seawater. I assume that your engine mariniser was relying on the very low rates of corrosive attack of cast iron by sea water when he did not fit an anode. An old cast iron engine that I once owned had an anode inside the water jacket doors but its rate of attack was pretty low. I would be tempted to add an anode inside the engine if at all possible to be on the safe side, but I wouldn't lose a lot of sleep if this proved impossible.

For info: on my GRP boat the previous engine was a raw-water cooled Bukh, it had a pencil anode that lasted a season quite easily. This engine is cast iron. I now have a fresh-water cooled Yanmar that has no anodes inside the engine but maybe one on the intercooler (must remember to check!). I have a shaft anode that has lasted for at least five years and looks to be in good condition still. Otherwise there is a hull anode, fitted by a previous owner, with internal wires connected to engine, two seacocks and P-bracket. This has remained untouched by corrosion throughout the time I have owned the boat. I am about to remove it as it is doing nothing for me.