Anodes

[Bigplumbs]

Many thanks VicS you seem to know your anodes

I removed the old ones yesterday and all seemed ok except the one behind the prop which was all but eaten away. I will weigh the good ones against my new ones to see what I have.

I will then replace all with the new ones (Alu) after I have antifouled the leg and them keep an eye on them through the season

Dennis

 

[Momac]

I am on fresh with occasional visits to salty water.
I currently have aluminium anodes which seem to erode at a slow rate.
Last year at lift out the anodes were a year old and slightly eroded so good for another year.
I know of others who do the same without any apparent corrosion issues .
My only concern is the aluminium anodes could develop a passive coating while in fresh water .

The only alternative for me would be magnesium and risk that they fizz to nothing when in salty water.

 

[Bigplumbs]

I am on fresh with occasional visits to salty water.
I currently have aluminium anodes which seem to erode at a slow rate.
Last year at lift out the anodes were a year old and slightly eroded so good for another year.
I know of others who do the same without any apparent corrosion issues .
My only concern is the aluminium anodes could develop a passive coating while in fresh water .

The only alternative for me would be magnesium and risk that they fizz to nothing when in salty water.

Martyn

Is it not possible to remove the Alu ones each year and abrade the surface with a wire brush and file or similar. That should work I think and would save the cost of new

Dennis

 

[VicS]

Many thanks VicS you seem to know your anodes

I removed the old ones yesterday and all seemed ok except the one behind the prop which was all but eaten away. I will weigh the good ones against my new ones to see what I have.

I will then replace all with the new ones (Alu) after I have antifouled the leg and them keep an eye on them through the season

Dennis

Make sure the anodes make good electrical contact with the leg. This may mean scraping clean the mating surfaces. with no paint or antifouling where they actually touch.

 

[andrewbarker]

FWIW, I've got a sportsboat with an Alpha One leg. It was fitted with new aluminium anodes last October.

I had the boat out at Sealift on Tuesday this week and to my surprise the ram anodes were virtually gone, the trim anode was completely gone and the block anode was about half worn. A very different experience to yours. I've replaced with zinc this time.

 

[Momac]

Martyn

Is it not possible to remove the Alu ones each year and abrade the surface with a wire brush and file or similar. That should work I think and would save the cost of new

Dennis

Yes it is possible to clean up the anodes . Thats what I did last time. I dont recall needing anything too aggressive .
The issue being the passive coating due to the slow rate of erosion of the anode in fresh water may mean the leg is not protected at some point which could be months prior to a lift out.
If things go to plan I will have the boat out again late in the season and will have some fresh anodes ready. The anodes aren't prohibitively expensive on my case. It's more about getting the best anodes for the job of protecting those expensive outdrives.

 

[Bigplumbs]

If the old anodes are zinc but the same size as your new aluminium anodes they will be much heavier ( more that 2½ times)

Zinc or aluminium anodes are suitable for seawater use. Aluminium is also suitable for brackish water

I have now replaced the anodes and the old ones were much heavier than the new Alu ones I put on. I will have a little scrape away at the old ones to see if I can see a mark showing what it is

 

[Bigplumbs]

Make sure the anodes make good electrical contact with the leg. This may mean scraping clean the mating surfaces. with no paint or antifouling where they actually touch.

Where the anodes fit the leg is all factory painted and in fact one of the large ones comes supplied with a rubber support and the ram ones have what looks like a non conductive base on the ram. I think for the Alpha 1 gen 2 the fixing bolts provide the connectivity to the leg with stainless steel wires interconnecting the parts of the leg

Dennis

 

[Bigplumbs]

FWIW, I've got a sportsboat with an Alpha One leg. It was fitted with new aluminium anodes last October.

I had the boat out at Sealift on Tuesday this week and to my surprise the ram anodes were virtually gone, the trim anode was completely gone and the block anode was about half worn. A very different experience to yours. I've replaced with zinc this time.

I would be interested to know what the one behind the prop was like

Dennis

 

[andrewbarker]

Sorry - I wasn't expecting to renew the anodes on this lift, so I didn't have the prop socket with me and Sealift were pushing me for time. Next time I'm down I'll have a look.

 

[TheOrs]

...lots of interesting and useful stuff...

Vic, thanks for that post - very informative.

This will corrode away as the zinc will not protect it. Rather; your aluminium leg will be protecting the zinc anode

Not sure why I posted that, as I know it's wrong! Just goes to show: 1) Don't post in the early hours of the morning & 2) Be wary of advice given in internet forums!