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Old 29 December 2003, 15:38   #1
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Anodes

Hi folks

I have just swapped the props on my RIB and decided the anodes need replacing.

While they are not expensive it is a real pain to swap them not having a trailer.

Given the life span is a function of the amount of zine present, would their be any benefit in having a couple of hanging anodes, connected to the others of course, just in the water near the fixed ones. These could be remoned when in use.

I know that one of the fixed anodes is connected to the drive ground but not sure about the ones on the trim rams.

Would this increase the life of the fixed ones ?, also would this effect the mercathode fitted.



All the best for the new year, Gary
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Old 30 December 2003, 09:12   #2
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Re: Anodes

Quote:
Originally posted by Garygee

Given the life span is a function of the amount of zine present, would their be any benefit in having a couple of hanging anodes, connected to the others of course, just in the water near the fixed ones. These could be remoned when in use.

I know that one of the fixed anodes is connected to the drive ground but not sure about the ones on the trim rams.

Would this increase the life of the fixed ones ?, also would this effect the mercathode fitted.


All the best for the new year, Gary
As long as the hanging anodes are close to drive and properly grounded they will still work.

Because the drive itself is grounded via various earth leads all the anodes bolted to the drive are also grounded (so long as the bolts haven't been overgreased or painted in any way.

It will probably help to prolong the life of the fixed anodes, but due to there location in direct contact with the Aluminum they will still erode quicker thn the hanging ones.
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Old 31 December 2003, 10:23   #3
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Gary have a chat with these people, they are also cheaper than the normal Mercury/Yam/Suz parts.

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Old 31 December 2003, 15:49   #4
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anodes

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Old 01 January 2004, 08:29   #5
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Thanks folks

Tried to give zincsmart a ring but must be closed for Christmas.

Will order a couple of big (cheap) anodes and suppliment the fixed ones. If it gives me a extra few monthson the fixed ones, it will be worth it as I could errode the free ones down to nothing.

Also does 9 months sound right for anodes, with a mercathode fitted ?. What are other people getting.

I know it is enviroment dependant but at present I have no idea if 9 months is average or not.


Thanks Gary
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Old 02 January 2004, 20:01   #6
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Gary, I have doubled the size of the original anodes because the life would have been 3-4 months. However, south coast mooring, with power cables in the jetties and water nearby

Your not using S/S props are you ?

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Old 03 January 2004, 06:59   #7
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Quote:
Originally posted by Pete7
Your not using S/S props are you ?
Does this make a differece?

Anyone know anything about freshwater anodes? Apparently they are different and corrode very quickly in the Sea.
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Old 03 January 2004, 07:09   #8
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Hi folks

Yes their is two stainless props (Contra-rotaring), plus a stainless shower unit.

The anodes are Zinc, I think freswater ones are magnesium.

Its the short life when used with the mercathode I am supprised at. I was hoping that the anodes would have been almost a backup, with little errosion when the mercathode was working.

Regards Gary
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Old 03 January 2004, 07:19   #9
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Quote:
Originally posted by Garygee
....with little errosion when the mercathode was working.

Regards Gary

Er, is it working, Gary?
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Old 03 January 2004, 10:41   #10
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Not sure to be honest and dont know how to tell.

Was hoping I could get some idea ho long other peoples anodes are lasting, with & without Mercathode.

Plan to have a chat with Barrus on Monday and see what they say.

Regards Gary
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Old 05 January 2004, 06:31   #11
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Gary, would be interested in the outcome too.

Daniel, yes does make a big difference, never had much of a problem with Al props but was shocked after a week to see what S/S did, although it wasn't a very scientific test. Steel prop shaft, brass thrust washer, bronze ? hub and S/S prop, with Aluminum leg, hmm nice.

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Old 05 January 2004, 14:04   #12
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anodes

re anodes for the Bravo III drive. There are several people you can buy these from, we sell them for 65.50 for the whole lot ie 5 anodes. The origional part is a Martyr anode and this is available from several people other than the mercruiser dealer.

Re how long they last. I can tell you on my own boat I found that we were replacing anodes every 6 months or less. However I fitted a standard bar anode to the transon then linked it to the drive in the engine room, you can get these from any chandler for about 20 and this has made all the "expensive" merc anodes last a season.

Usually when changing from alum to s/s props you should "beef up" your anode protection but this would have been done on your drive as standard as the Bravo III drive propellers are only available as stainless steel.

If you use the boat in salt water you can use zinc or aluminium anodes. Manganese anodes are ONLY for fresh water use.

Hope that of help
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Old 05 January 2004, 14:30   #13
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Julie, is that manganese or magnesium?
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Old 05 January 2004, 14:35   #14
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Thanks for info. Will zinc or aluminium provide enough protection in fresh water, and if so what are the advantages of (manganese or magnesium which ever it may be).
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Old 06 January 2004, 07:45   #15
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Hi folks

Thanks for all the info.

After talking to people, anode people, Barrus etc the general option is that 8 months is very good life from anodes and that for that the Mercathode must be working well.

Looks like the Mercathode works best in static water i.e. moving water (tidal) weakens the effect.
Fitting a second Mercathode should double the protecting effect and at 60 may be a good value option if it increases anode life.

Also got told by Barrus that their anodes are Alluminium now and not zinc.

They informed me that you should get 850-1000mV potential between the water ( meter probe) and the drive, which I will now check.

Have ordered normal zinc anodes for the drive plus two big 2.8KG zincs which I plan to fix to the transom connected to the drive ground. Prob check the A Frame is grounded and if not ground it and connect the anodes onto the bottom of this, which at rest is below the water line.

Have just swapped the porps for bigger pitch ones and on cleaning the props which came off showed no electrolic or other corrosion, just some brown discolouration.

Will fit and keep a close eye on errosion or anodes and any corrosion to see how things go. I will repost in a few months with any findings.

Thanks Gary
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Old 06 January 2004, 07:58   #16
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Gary, is that just 60 for a full mercathode system?
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Old 06 January 2004, 09:16   #17
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Can't be its more like 300 for a system the last time I looked. 2.8 kg sounds rather big for an anode, our 80' hard boat only had three of these. When I said I had fitted a big one it was like 8 oz.

Gary the props shouldn't show any marks as they are a more noble metal than the anodes which corrode. Are you using s/s wire to connect the anodes to the drive or copper ? just a thought.

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Old 06 January 2004, 10:41   #18
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Hi Pete

The cost was for just a duplicate controller, supplied from Barrus.

The anodes are big, cheapest pound/kg I could get.
As I need to lift the boat to swap, no trailer the bigger the better.

These would go on the transom to supliment the ones on the outdrive and being on the transom would not create any drag when on the plane.

Plan to bolt them to the A Frame mounts so will be fixed with either M8 or M10 Stainless bolts.

Regards Gary
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