A query about anodes.

[Matticrues]

Hello all ,

 

I am new to boating , and have a query about anodes.

 

I recently bought a 55 foot narrowboat with a steel hull. My survey before purchase stated that my current anodes were in a serviceable condition. Soon after purchase I had her taken out of water and blacked ( the right thing to do ) . I am now thinking that I should have had a couple (or more) anodes fitted at this time. I won't be taking her out of water for at least another year , and am spending a bit of time in a marina hooked up to a landline while I get her ship-shape before I set off as a continuos cruiser and explore the waterways. My question is this ... Would it be worth buying an anode or two and dangling them over the side with wires that are connected to the steel shell. With my current knowledge I think that they would work, but maybe the resistance in the connecting wires would be too high to make this an effective protection.n I am thinking of connecting a galvanic isolator but many people have said that it is not really worth it for short stays in a marina.

 

.. . ..Also has anybody got any advice on how to set up an earthing cable?

 

Any thoughts would be much appreciated.....even a lol would do......lol!

[matty40s]

1st idea, don't bother, if anodes are in serviceable condition, this usually means you have at least two years life in them.

 

If you are on shoreline in a marina for 12 months, this is not a short stay and a lot of corrosion could potentially happen in that time ( although you have been blacked).I would fit a GI, not expensive and may save you a lot in the long run.

[Matticrues]

1st idea, don't bother, if anodes are in serviceable condition, this usually means you have at least two years life in them.

 

If you are on shoreline in a marina for 12 months, this is not a short stay and a lot of corrosion could potentially happen in that time ( although you have been blacked).I would fit a GI, not expensive and may save you a lot in the long run.

 

Thanks for the reply. I really just want to know if it would work, as I could always get these anodes ( the ones over the side ) welded on next year...?

[Stilllearning]

It is said on this forum that a GI should be fitted when you live in a marina and are plugged in to a landline.

Evidence from my use of boats in such a situation is that it was not needed (16 years in marina, on landline, no noticeable corrosion, on 2 different boats) but if you can be convinced it is worth it, go ahead.

[NilesMI]

Matticrues, I had to decide about these things too.

 

Bought a boat 54' about 2 yrs ago, following much the same idea, spending a year or so in a marina before setting off exploring.

 

On the GI, having listened to lots of conflicting advice, I decided to fit one, knowing I'd be hooking up to a marina shore line for a year or so. The point is that you only need one boat earthed to the same shore supply to conduct their leaky current through your hull and corrode it. The first you'd know about it, is the corrosion itself and from what I've heard it can happen quite quickly.

 

The shoreline side of the GI goes to the shoreline earth. The boat side of the GI goes to your boat's AC system earth, PLUS the grounding point on the hull (mine was on an engine mount) via a cable of at least the size of the system earth. Very simple to fit.

 

The GI places a barrier in the AC earth to shoreline in the form of a votage step. If another boat, or potentially (no pun) the shore supply itself has a fault with a larger potential difference, the you'd be back to having your hull in the circuit and potential corrosion. Real isolation requires an isolating transformer, but they far more bulky and cost ££££.

 

My boat had been blacked and anodes replaced 10 months before I bought her so I left everything be, anode-wise. 2 years later I have just had her out for blacking and replaced all (6) anodes. There was some slight pitting to the hull, but it is 22 years old so not unexpected and nothing to cause me concern.

[Matticrues]

Thanks again. I am only planning on being in the marina for a month. and disconnect from landline over night.

 

It does sound like it is a good idea to get a GI , and I will look around for the earthing spot. Would it be obvious where it is? ...Or is it just a place with a good connection to the shell?

[blackrose]

You may already have a GI so check that first- and check that it's working.

 

Regarding hanging anodes over the side; this can be done but you would need to take the paint off where the cables connect to the hull above the waterline in order to ensure a good electrical connection.

Edited July 9, 2014 by blackrose

[Boat&Bikes]

On the subject of GI they can be brought for not a lot more than standard types, complete with plugs so that you simply plug into your shoreline cable.

 

Ian.

[mickp]

I think your idea is very good,while cruising put you anodes away ,but hang a few of the sides when you return like fenders.also you could cover the center of the boat as anodes normally just front and rear.im sure it would be possible to attach hull connections for easy attachment

[Pete & Helen]

Thanks again. I am only planning on being in the marina for a month. and disconnect from landline over night.

 

It does sound like it is a good idea to get a GI , and I will look around for the earthing spot. Would it be obvious where it is? ...Or is it just a place with a good connection to the shell?

 

The GI goes in line with the incoming earth wire, not from there to the hull. in other words, cut the earth wire that comes from the back of the shore power socket and insert the GI

 

If your only going to be in a marina for a month then to be honest I wouldn't even bother with a GI unless you want to future proof your boat for when you use shore power in the future