Anodes for Salt-v-freshwater cooled engines

[alanporter]

I have a Westerly Renown that originally had a Volvo salt water cooled engine (MC11C). On the outside of the hull there is a plate zinc anode attached by two through bolts. The forward bolt has a wire running to the cooling water intake valve then on to the engine common ground. The after bolt has two wires running aft, and I can't for the life of me see where they are connected, they seem to disappear under the fuel tank. My secondary question is does any Westerlyite know where these wires go ?
My most important question is - I have changed my engine to a fresh water cooled Isuzu ( such a good engine I feel like kissing it every time I go aboard), so, do I need the external plate anode anymore ? My feeling is that it was put on to protect the salt water engine which did not have any internal anode pencils, while the new engine does. I am not an expert in these matters, so I need the wisdom of the forumites. Many thanks in anticipation.

 

[VicS]

[ QUOTE ]
does any Westerlyite know where these wires go

[/ QUOTE ] I know the Berwick pretty well but I have no real idea where these wires go.

One thing I can tell you for sure is that an anode on the outside of the hull will have done nothing in the way of protecting the engine cooling system. An anode must be located reasonably close to what it is to protect and be within "line of sight of it". That last bit does not have to be taken too literally as anodes can "see" round curves but they will definitely not be able to "see" all the up the cooling water intake, through the pipe to the gearbox cooler, through that, back to the pump, through that and round the plumbing on the engine.

The connection to the water inlet may have been made to give that cathodic protection, but that is unecessary if the skin fitting, valve and strainer are original bronze or DZR brass. It must be said that the strainer baskets appear to have been ordinary brass and dezincify.

The wires that go under the fuel tank are a mystery. If one had gone to the stern gland or to a brush running on the propshaft I might have said it was an attempt to protect the prop and shaft but again in my experiece unnecessary and ineffective anyway unless the anode was mounted close to them.

A connection to the rudder?

One thing that is another possibility is that it was some kind of earth for a pushpit mounted Decca aerial. The Berwick I have sailed for many years has wire running from one of the pushpit feet to the strainer which was put there as an earth for that purpose.

Do you have a shorepower installation that has been earthed to what on the face of it is an ineffective and perhaps unnecessary cathodic protection system.

My thoughts would be to forget it all unless it is providing a shore power earth but you would would have to do something about the bolt holes though the hull.

Is the fuel tank in the same position as that in the Berwick namely above the stern gland and back a little way from there or does the aft cabin mean it is different.