April 12, 2020 at 09:12 #26687Arild JaegerParticipant
Our Nic 38/10 has one large zinc anode about one foot forward of the propeller on the port side. It is connected to the through hull fitting for the propeller shaft by a naked copper wire. We have not changed this anode in our 16 year ownership time. There is still a good bit of zinc left, but this year it will go.
I do not like the position right in front of the propeller, where the anode disturbs the water inflow.
A few years ago, I noticed that the propeller appeared to be discoloured and pitted some places. I believe the grease between the stern tube and the shaft creates electrical insulation. I therefore added a propeller nut anode. This almost goes away every year, and therefore seems to be very useful (and expensive).
Maybe I should just skip the large anode or alternatively fit a smaller one with through hull bolts behind the rudder and with an inside wire connection to the stern tube?
I would appreciate if you could share your experience with anodes on the Nicholson 38.
ArildApril 15, 2020 at 22:16 #26688João de Almeida FarrachoParticipant
I’m taking care of the same with Conche. That’s a very good question indeed and I’m curious to listen about solutions we’re using too.
I’m a recent owner and have not implemented so far a cycle maintenance.
But I’ve set already the 3 Zinc anodes I think to be a solution.
1) Zinc anode next to engine’s heat exchanger. This one should be checked and substituted regularly.
2) Zinc cup bolted to propeller nut . This one protects propeller and I believe it lasts less than 10 months on our case.
3) Large zinc fixed with trough hull bolts. Then two 10mm copper wires run from the bolts to link engine block and stern gland ( stern tube greaser system)
4) Finally the shaft has a flange and there is to link with a copper wire the two sides of the flange if it is insulated type.
This is what I have in mind.
JoãoOctober 5, 2020 at 23:20 #26751VanParticipant
Our prop shaft has a brush (carbon, just like the brushes in an electrical motor) that is in contact with the prop shaft just forward of the stern tube. The brush is wired to the through bolt attached to the primary external zinc. I (try) to remember to keep that area of the shaft clean to ensure a good electrical connection. I have no way of knowing if it is doing a good job!
Our primary zinc is an approx 12″ x 1.5″ x 1″ rectangle that is bolted (2 bolts) to the starboard side about level with the prop, and about 1 foot forward of the prop. This sits in a recess in the hull so that it is not really protruding very much. We are moored in brackish water, more fresh than salt, and so we don’t seem to use zincs very fast.
I don’t recall if on our boat, the castle nut that holds the prop on the shaft leaves enough room for a zinc. I don’t think so. But it seems like a very good idea.
At dock, we also deploy a “guppy”, which is a piece of zinc, on a copper wire that is wired to the ship’s bonding system, and dropped down into the water. It does decay away, we replace it about every year.
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